Treatemnt of subfertility-Dos & Do nots. Please put Questions

Drugs commonly used for subfertility Tr ?

Tips in Doshera –Enjoy Doshera with someone who is very special to you !!!

Happy Diwali. PRACTICAL TIPS FOR INFERTILITY MANAGEMENT

Tip 1 ) Clomiphene should be given maximum for 3 months with USG monitoring at least in second cycle if unaffordable for 1^st cycle./Transport inconveniences.

Tip 2 ) Dose of CC should be upto 100 mg for 5 days. Day 3 start is best so that by the time implantation occurs at least adverse effect of ET will pass off. Extended regimes are not usually practiced until ART settings.

Tip 3 ) No routine hCG as trigger in CC cycles. It may arm in fact due to premature ova release. But f IUI then one rigger when Foll dia is 22 & ET is at least > 8 mm. It is uncommon in CC cycles to achieve EDT of > 10 mm  hCG should be combined with CC only when IUI is to be done or delayed LG surge is suspected.

Tip 4 ) Not to add oestrogen in CC cycles to promote ET.. Better to move on to HMG cycles if unassociated with hyper prolactinoma. If ET is suboptimum oral / vaginal /Transdermal oestrogen has no role.Better  to proceed for HMG cycle alone preferably  after a gap of 1 month so that ilexes oc passes off(usually 60 days). Some uses CC on alt months if wife is young with the idea that elects of previous cycles Classes off. raid oaf ill effects of CC on endometrium ( 40%).

Doshera :Tip 4 ) CC  +  bromocriptine for spikes (sudden rise of PRL –Transient hypwrproacyinaemai due to rise of serum E2 as CC recruits 4-8 growing follicles which releases much E 2. Serum E 2 promotes PRL secretion in some cases but not all, The another danger of exponential ribose of F 2  is premature rise of LH (20%) cases which can provoke release of still immature ova –which is to immature to fertilize., Bromocriptin can also be iced in cases with  galactorrhea unassociated both hyperprolacunaemia ,This symp s nowadays called Inappropriate lactation but an inquiry should be done about drug induced  Galactorrhoea, All galactorrhea the secretion must be examined under microscope for fat droplets. ,If PRL is > 100 ng/ml on two occasinals then MRI is mandatory including eye exam.. Empricial  use of bromocriptine has no role.

Doshera Tip 5  ) CC + Dexamethasone in CC resistant chronic anovulatory obese PCOS.

Metformin is given only to those pts who do not want immediate pregnancy.

Tip 1 ) Ovarian drilling has excellent results

CC   + gonadotrophin reduces the requirement of gonadotrophins but does not increase the pregnancy rate.

Tip 6  ) Letrozole is very useful in CC resistant cases and PCOS, when baseline E2 is >35pgm/ml.

Letrozole+ gonadotrophins give excellent pregnancy rates with less number of gonadotrophins used and lower multiple pregnancy rate.

Tip 7  ) Low dose FSH should be used as a first line treatment for anovulatory PCOS patients.

r-FSH and rhCG are superior over the urinary products and give very high pregnancy rates.

Tip 8 ) Gonadotrophins + antagonist + IUI has given excellent results to us, in patients with thin lean PCOS.

Tip 1 ) Medical management of male infertility helps to improve the count and motility and IVF and ICSI may be converted into IUI cycles.

Gonadotrophins by Prof. Ishidori regime helps improve count in idiopathic oligozoospermia.

Aspirin + Corticosteroids is very useful in patients with early pregnancy loss due to Antiphospholipid syndrome in our series. Corticosteroids are not continued after 3.5 months of pregnancy. Then Heparin is used.

Investigations:

Investigations should not be asked for without provisional diagnosis.

Packages and profiles for infertility are useless.

FSH/LH is generally not required for diagnosis of PCOS and does not add anything to your management.

S.DHEAS should not be asked for routinely for all the patients of PCOS.

Fluctuating prolactin levels between 25-50 ng/ml are not of much clinical significance and bromocryptine is usually not required.

S. Oestrogen and S. Progesterone levels during follicular monitoring are not required now with good USG machines available.

Antisperm antibodies testing in serum of male of female has no value.

Normal PCT more or less rules out the male infertility and is very satisfying to the couple.

Procedures:

Superovulation with gonadotrophins with IUI is a treatment of choice in cases of idiopathic infertility and has very high success rate up to 80% in 6 cycles.

Only IUI does not improve pregnancy rate unless it is backed by good stimulation protocol, good USG, monitoring, proper semen preparation and good luteal support.

Good IUI preparation means 6-8 million count with>95% motile sperms.

IUI should be done at 36-38 hours post hCG routinely but double IUI is done when perifollicular PSV > 20 25cms/sec.

CO2 incubator is a must for good IUI preparation.

Ovarian drilling: It gives excellent results in CC resistant cases. Four punctures are useless and number of punctures should depend on the ovarian volume. Mostly all PCOS patients require at least 15-20 punctures or even more for duration of 1 sec with 400 watts.

After ovarian drilling I go for superovulation with IUI without wasting any cycle.

All laparoscopies must be combined with hysteroscopies and continuous recording should be given to the patient for all future references. This will save the patient from unnecessary repeat laparoscopy.

Tubal recanalization is useful only in patients with blocked tubes due to tubal ligation, otherwise IVF is a better option.

D & C has no role in modern infertility except for diagnosis of genital tuberculosis. Hysteroscopy must be preferred to HSG and combined with laparoscopy.

Unnecessary removal of fibrodis during routine endoscopy for infertility should be avoided to prevent iatrogenic infertility due to tubo-ovarian adhesions.

All septa in uterus do not require resection. Results are comparable with or without surgery.

In patients with risk of OHSS, (cut off E2 5000pgm/ml), IV albumin or HES, at the time of pick up & Cabergol in 0.5 mg for 8 days has avoided OHSS in most of the cases.

Transvaginal aspiration of fluid in OHSS is the treatment of choice to improve renal parameters and clinical improvement rather than the last resort as mentioned in previous textbooks.

IVF and ICSI:

Counseling for the procedure is a must.

Counseling for the total expenditure and the results-pregnancy rates can avoid all litigations and disharmony.

IVF is done after 6-9 IUI failures in idiopathic infertility.

ICSI is done for low count, which is not improved by medical management.

Many patients conceive spontaneously or by IUI after IVF/ ICSI failure.

Normally endometriosis of grade III or IV requires ART.

Embryo donation should be discussed with all the patients above 38 or poor responders, even if younger, because results of ovum donation are always better for these patients.

USG:

Use only TVS for monitoring of infertility patients.

Baseline scan on day 3 is a must to have UCL as well as to decide the starting dose of stimulation protocol, as the baseline scan determines PCO, normally responding and poor responding ovaries.

hCG timing should be properly determined by 2D, colour Doppler, pulse Doppler, and 3D power Doppler of follicle and endometrium. This is the secret of success of IUI.

Always do USG at five weeks for confirmation of intrauterine pregnancy and at 6 weeks for cardiac avtivity.

We do nuchal scan for all pregnant patients between 11-14 weeks.

Detailed structural scan including fetal echocardiography & neurosonography is done between 18-20 weeks.

We evaluate all pregnancies by colour Doppler at 30-32 weeks for future prognosis and management.

Complete documentation of all scans in detail is a must.

Prescription:

Prescription is your image, a doctor is evaluated by his prescription, not by his face.

Length of prescription is inversely proportional to your knowledge.

Many a times prescription indicates the year of passing.

Do not write because you have to write something.

Avoid writing drugs which are not useful to the patients.

Save patient’s money for better, indicated, costly treatment.

For Juniors:

Be transparent and honest with patients.

There is no option to hard work.

Wise persons learn from other’s mistakes.

Do not be afraid of criticism.

It is very easy to criticise, but very difficult to appreciate your colleague.

Keep away from short term gains.

Try to see the roots rather than fruits on the tree.

Deep updating your knowledge.

Books and journals help us like GOD in crisis, so keep them with you.

Basic Transvaginal Sonography

Ultrasound (US) is the most useful and indispensable investigation for evaluation of gynaec or infertility patient. US of the pelvic organs uterus, ovaries and adnexa must be done by transvaginal route for better visibility and accuracy of diagnosis. This is so because of close placement of the high frequency probe (6-12MHz) that has better resolution. Transvaginal route can not be used in virgins or in patients with local vaginal problems, and in these patients, transbdominal sonography with full bladder may be done. This route has a disadvantage of poor resolution because of more distance of the pelvic organs from the probe, maternal fat, maternal bowel loops and use of the low frequency (3-5MHz) probe which has evidently lower resolution than the high resolution, high frequency transvaginal probe. Approximately 42% of ovarian details are missed by transabdominal scan¹.

      But transrectal sonography in such cases is more preferable and informative as compared to transabdominal approach. The probe used is transvaginal or endocavitary probe, a high resolution probe so resolution is very similar to that of a transvaginal examination. But the disadvantage is that rectal placement is much more painful than transvaginal placement and needs bowel preparation. Moreover the orientation of pelvic organs that appear on the image created by transrectal scan is different than that of a transvaginal scan and so interpretation may by a little difficult. Therefore the approach of choice is transvaginal.

Method:

      For transvaginal scans, at least a verbal consent of the patient is essential. Patient is asked to empty the bladder. Patient is placed in lithotomy position on the gynaec couch in the same way as for per speculum or per vaginal examination. Ultrasound jelly is put on the head of the transvaginal probe and then the probe is covered with the condom, not to allow any air between the probe and the condom. A small amount of jelly is then placed over the condom on the probe head and the probe is gently slided into the patient’s vagina. Counselling the patient before examination and explaining the whole procedure and adequate privacy, helps eliminate the anxiety and resistance. In case of difficulty in introduction of patient’s resistance to introduction, she is advised to take deep long breaths with open mouth i.e. deep inspirations and long complete expirations. In spite of that, if introduction of probe needs any force, the pressure should be exerted posteriorly towards the rectum which will make introduction of the probe into the vagina easier. Probe is introduced in the longitudinal position. That is the position in which the indicators on the probe remain up, facing the roof of the room that is on anterior aspect of the patient. (figure 1)

      This indicators on the probe match the indicator (logo of the company) on the screen. (figure 2)

      This means that if the indicator on the screen is on the right side of the screen, the structures anteriorly placed are on the right side of the screen and vice a versa.

Basic probe movements:

      There are basic four types of probe movements.

In and out (figure 3)

Side to side or spanning movement (figure 4)

Rotation movement or screwing movement (figure5)

Up and down or antero-posterior movement. (figure 6)

Equipment settings:

      Usually there are presets on all the equipments for different scans and there is one for gynaec scans also. The advantage of using a good and proper preset is that one does not have to change the gain, depth and contrast setting with every scan. The transvaginal probe, if a multifrequency probe, either 5-9MHz or 6-12 MHz is preferred.

Optimizing the image:

      The basis of correct diagnosis, correct Doppler study and good 3D image is a good quality b mode image. The basic settings to be made with each scan and several times in each scan are

Scanning angle:

The scanning decides the width of scanning area. The scanning angle is kept, to its full limits when the probe is introduced into the vagina, so that a pilot view of all pelvic organs and their relationship can be studied. The maximum scanning angle for different transvaginal probes vary from 120^o-180^o. Once the general anatomy is understood and one needs to concentrate on a particular organ, e.g. uterus or ovary, then the scanning angle in narrowed to the breadth of that particular structure. This improves resolution of the image. (figure 7 a,b).

Scanning depth:

Same as for scanning angle the scanning depth also is set at 8-10 cms in the preset. But after the overview of the general anatomy, when one concentrates on a particular organ or lesion, the scanning depth is also decreased, so that the region of interest fills almost the whole image. This maneuver also improves resolution. (figure 8 a,b)

Zooming:

After the overview scanning & decreasing the scanning angle and depth, image should be zoomed large enough to fill up at least 3/4^th of the screen. One may zoom the whole image (Panzoom) or may use a zooming box to decide and define which part of the image needs zooming (HD zoom). Again this process also improves resolution of the image. (figure 9 a,b).

Setting the focal zone:

The arrow head on right side of the image indicates the focal zone. Focal zone is the level at which the image is the sharpest. Therefore focal zone is always set at the level of area of interest. There is also an option of having more than one focal zone, when there are multiple levels at which the image needs to be sharp. But increasing the number of focal zones, decreases the frame rate and therefore usually single focal zone is selected. (figure 10 a,b).

Gains:

It is known that structures far from the probe appear hypoechoic (darker), than what they are and this may cause an error of diagnosis. A solid structure may appear cystic. When the image is too dark or unclear, the examiner may be tempted to change the gains of the image. But changing gains inadvertently may lead to erroneous diagnosis. Therefore in all doubtful, difficult situations, the gains are set in such a way that the urinary bladder appears anechoic and echogenecity of other structures are assessed in relation to bladder. (figure 11 a,b,c).

Orientation:

      The probe position with indicators towards the roof normally shows the long axis of the uterus. It may be anteverted or retroverted and anteflexed or retroflexed. Version indicates the direction of cervix where as flexion indicates the direction of fundus of the uterus. Anteversion is when the cervix from external os to internal os is directed from posterior to anterior and retroversion is when cervix from external os to internal os traverses from anterior to posterior. When anteflexed the uterine fundus will be directed towards the indicator on the screen and urinary bladder is also seen on the same side of the screen. When retroflexed fundus will be on the opposite side of the indicator and the urinary bladder. (figure 12 a,b,c,d)

      If the uterus is not seen in this view, it means that the uterus is deviated towards one side. When it is deviated it would indicate that either it is pulled on the side of the pathology like adhesions or is pushed away by the pathology which is on the opposite side: an ovarian or tuboovarian mass. The second possibility is congenital abnormality of the uterus like unicornuate or bicornuate uterus or uterus didelphys. We shall discuss the uterine abnormalities in the chapter dedicated to it.

      Now having located the uterus in the midline and decided whether it is anteverted of retroverted, its structure is evaluated systematically. With the probe in the same position it is spanned from right to left side of the patient, scanning the uterus in long axis from one side to other. A true long axis is when whole endometrial cauity & cervical canal are seen in single section.

The endometrium:

Symmetry of the endometrial shape (pear shaped)

Endometriomyometial junction

Intraendometial lesions like polyp, adhesions etc.

Corresponding with the phase of the cycle

Endometrium is the broadest at the fundus and narrows down smoothly towards cervix. In all the phases there is a thin hypoechoic zone seen surrounding the echogenic outline of endometrium, which is known as endometriomyometrial junction or junctional zone. Breach in this zone is suggestive of invasive pathology of endometrium, either infection, adenomyosis or neoplasm. Any echogenic solid lesion in between the lines of endometrium is suggestive of pathologies like polyps, synechiea etc. Depending on the phase of the cycle, endometrium is expected to be thin linear in early follicular phase, triple line in preovulatory phase and thick and echogenic in secretory phase.(figure 13.a,b).

The myometrium:

homogenecity of the myometrium

mass lesions

scar tissues

Myometrium is homogenously echogenic normally.  Any generalized heterogenecity or lovalized hypo/ hyperechogenecity is suggestive of a pathology. The commonest ones are fibroid and adenomyosis. (figure 14 a,b)

The serosa:

Smoothness of contour

Continuity

Maintenance of tissue.

interface

      Outer layer of uterus is covered by peritoneum and is the serosal layer. It defines the margins of uterus and therefore its integrity confirms that the uterus is normal. Any mass lesion in the uterus changes the contour of the uterus and therefore the smooth pear shape is distorted. (figure 15) In and out movement of the probe, confirms the mobility of the uterus and rules out adhesions.

The cervix:

Length & mucous : the cervical length is assessed by indentifying the internal os. Internal os can be identified by two landmarks. 1. The entry of uterine vessels.  2, cervical glands surrounding the cervical mucosa. Thickness of endometriomyometrial junction is narrowest at the internal os and beyond that towards cervix is markedly increased because of these cervical glands. Presence of fluid (mucous) in the cervical canal may also define the cervical canal. (firure 16)

Cervical lesions like polyp, fibroid, nabothian cysts etc.

Serosal integrity as for the body of the uterus is also essential for the cervix

Measurements:

Physiological uterocervical length is measured in this view. It can be measured as a continuous tracing from the fundal endometrial tip to the external os, or it can be a summation of two measurements: fundus to internal os and internal os to external os. This uterocervical length must be used for IUI and embryo transfer. The actual anatomical uterocervical length can be measured from the fundal serosa to the external os. The endometrial thickness can be measured from outer margin of peripheral hyperechoic lines of endometrium and at the thickest part of the endometrium.(figure 17) Visual assessment of symmetry of thickness of anterior and posterior myoetrium is done and if in doubt actual measurements may be taken. Myometrium is measured from outer margin of outer hyperechoic line of endometrium to the serosa, perpendiculat to endometrium.

      Now rotate the probe 90^o anticlockwise. This maneuver will give transverse view of the uterus with the right side of the patient on right side of the screen. (figure 18) In this transverse position also the whole uterus is evaluated from the fundus to the cervix by moving the probe up and down in the vagina. This survey should give a complete idea about the anatomy of the uterus and the exact location of any fibroids, etc. On this section measure the transverse and aneroposterior diameter of the uterus.

      Now span the probe towards right side and in transverse position only at the level of uterine cornu, gradually look at the adnexa and follow it to the ovary. Extend the movement upto the lateral pelvic wall if ovary is not located. Locate and assess the ovary in a true transverse section and then rotate it 90^o to get a true long axis of the ovary, the largest longitudinal diameter. Measure the largest longitudinal, transverse and AP diameter of the ovary, which will give the ovarian volume. Assess the ovaries for any pathological mass. Then span the probe, come back to the mid line and follow the same procedure for the opposite adnexa. (figure 19). In and out movement of the probe with the ovary in view or pressing from the abdomen when probe is looking at the ovary and checking the sliding of the organs against each other confirms mobility of the ovaries and rules out adhesions. This is also known as Timor-Trsitch sign or a sliding organ sign.

Adnexa:

Look for mass lesion.

Localized fluid collection

Thickening of the adnexa

Come back to the midline and angulate the probe head posteriorly and look for fluid in pouch of Douglas.

While removing the probe gently, have a close look at the cervical   canal.

This completes the 2 dimensional or b mode routine transvaginal scan (TVS).

Colour, pulse or power Doppler can be added as and when required.

For colour Doppler of the uterine artery the probe is brought back in the middle in longitudinal plane and then again moving laterally, serpinginous tubular structure is seen at the level of internal os, which is the uterine artery. It can also be traced in transverse axis of the uterus, moving the probe to the level of internal os, when arteries will be seen on both the sides. Moving from midline laterally, shows iliac vessels, which are large prominent vessels running mediolaterally, superioinferiorly. After tracing these vessels, the probe if angled slightly medially, shows a vessel perpendicularly crossing them, this is uterine artery. (figure 20)

Moving laterally from this point towards adnexa will show another vascular structure heading towards the ovary, which is the ovarian vessel. Colour Doppler is also used to evaluate the endometrial flow. The blood vessels entering the endometrium are branches of spiral artery and are seen as vessels perpendicular the endometrium. The ovarian stromal vessels are studied for baseline scan. These are the vessels which are lying in the ovarian stroma and note close to the follicles. This finishes the basic transvaginal scan.

Ultrasound of Adnexal diseases

      Ultrasound is accepted as the primary imaging modality in the evaluation of adnexal masses. Ultrasound is a very useful tool for localizing the origin of pelvic mass and to study the morphological characteristics of the mass. It is based on this morphology that these masses can be categorized as benign, possibly malignant or malignant. Doppler is a important tool for differential diagnosis of adnexal lesions. Several meta-analyses revealed significant higher performance for combined techniques using morphologic assessment and Doppler ultrasound indices than B mode evaluation alone¹.

Adnexal lesions can be divided as…

Ovarian lesions

Tubal/tuboovarian lesions

Miscellaneous lesions: Paraovarian cysts, peritoneal inclusion cyst and broad ligament fibroids

Ovarian lesions:

      Ovarian are physiologically active organs and continuous change is seen in their morphology throughout the menstrual cycle. This is in the form of follicle recruitment, maturation, rupture and formation of corpus luteum. Therefore cystic structures appear and change in morphology from time to time in the ovaries. Apart from these, ovaries also play a host for several other pathological lesions like endomeriomas, dermoid cysts, serous and mucous cystadenomas, endometriomas, fibromas and ovarian epithelial carcinomas.

Tubal lesions:

These are mainly inflammatory lesions of the fallopian tube. They may be acute or chronic and may present as salpingitis, hydrosalpinx or complex tuboovarian masses. Tubal neoplasms are not very common. Ectopic pregnancy, tubal or ovarian is an adnexal lesion that is very important to diagnose early but is often missed.

Adnexal lesions:

 Other than tubal or ovarian, are broad ligament fibroids or paraovarian lesions. These lesions need to be differentiated from pedunculated subserosal fibroids.

Ovarian lesions:

     Before describing a lesion, it is important to decide the origin of the lesion. The signs used to confirm the origin of the lesion from the ovary are:

     Place a probe in such a way that the lesion and the ovary are seen in the same frame on the screen. Apply pressure with the probe, to separate the two. If probe pressure can displace the two away from each other, the lesion is not arising from the ovary. If the two cannot be separated, the lesion is either adherent to the ovary or it is arising from the ovary.

      If the lesion is arising from the ovary the lesion will be partially or completely covered by normal ovarian tissue and is typically described as a ‘rim sign’ or ‘beak sign’. (figure 1).

      Having confirmed the origin of the lesion from the ovary, the differential diagnosis of these lesions can be thought of. We would prefer to do this by dividing these lesions into different categories based on their ultrasound appearance.

Ultrasound based classification of ovarian lesions:

Nonseptated clear cysts

Cysts with internal echogenecites and septae.

Solid lesions

Complex lesions with cystic with solid areas.

Nonseptated clear cysts:

There cysts are thin walled, have no internal echogenecities, no septae or no solid areas in it.

     The lesions / structures in this category are:

Follicular cyst

Simple cyst of the ovary

Follicular cyst:

    This is an intraovarian structure. Follicle starts growing, in early follicular phase. It grows till 18-24mm in diameter before it ruptures due to the surge of luteinizing hormone to release the ovum that it contains. If the surge is inadequate or does not occur, the follicle will not rupture and will result in a hormonally inactive/ only minimally active structure. This is termed as a follicular cyst when it grows beyond 25mm and persists in luteal phase of the cycle or even in the subsequent cycle. Contrary to the normal follicle, the follicular cyst shows scanty and high resistance flow. But it is ultimately a physiological cyst and would resolve on its own over a maximum period of 4-6 weeks.

 Simple cyst of the ovary:

     It is a thin walled intraovarian cystic structure usually larger than 5cms. Doppler shows no flow. It does not resolve on its own and may require ultrasound guided aspiration usually.

Cysts with internal echogenecities and septae:

The commonest lesions in this category are:

Corpus luteum

Heamorrahgic cyst

Luteinized unruptured follicle.

Endometrioma

All these structures have thick, shaggy walls, internal echogenecities and nonvascularized septae. The appearance may vary viz. absolutely isoechoic homogenous, clear fluid, lacelike or cobweb pattern or ground glass appearance.

Corpus luteum is physiologically active cyst. It appears as a result of ovulation from the follicle. Its existence usually is till the end of the luteal phase. It has thick, crenulated walls. Contents the cyst show heterogenous echogenecity with or without septae. The echogenecity and appearance of the contents may change at different times. Doppler gives almost a complete ring of vascularity with low resistance (RI<0.5). That is the most characteristic feature to differentiate it from other lesions with similar appearance on b mode.

2. Heamorrhagic cyst is a cyst containing blood in any of its forms. It is most of the times a result of nonresolved corpus luteum but is hormonally inactive and therefore shows very scanty and high resistance blood flow. It changes echogenecity over time due to fibrinolysis of the clot.

3. Luteinized unruptured follicle (LUF) has thick, echogenic but not very shaggy walls, and does not contain blood or blood products. Therefore it does show low level internal echogenecity but is less heterogenous and never lace like or cobweb echogenecity.

      The three above described lesions are physiological ovarian cysts and 53-89% of these show spontaneous regression on follow up after 4-6 weeks². To avoid confusing these malignancies, examination must be done in early proliferative phase or two examinations 2-3 weeks apart should be done so that assessment can be done in two different phases of menstrual cycle and complete or partial resolution of these lesions can be demonstrated.

4. Endometrioma

      Endometriosis is detected in 15% of infertile women. It may cause acquired dysmenorrhoea, dyspareunia, irregular bleeding and infertility. 1/3^rd to ½ of the ovarian endometriotic cysts are bilateral. Most endometriomas are positioned medially or retrouterine.

      Features typical of endometriomas are thick shaggy walls with or without septae, internal echogenecities, ground glass appearance, fluid levels, linear echogenic flecks in its walls (figure 5) and pain on pressure with the probe. Adhesions are very common. Solid areas may be sometimes seen. Streaming sign is often seen. This is slow downwards movement of small low level echogenecities seen in endometrioma (chocolate cyst). Mean gray value (MGV) is significantly higher in ovarian endometrioma compared to all other kinds of ovarian cysts. MGV cut off>15.560 had a sensitivity of 85% and specificity of 76.5% for diagnosis of endometioma³.

On Doppler:

      Scatterred vascularity at ovarian hilus with moderate vascular impedance has been described. The ovarian hilar RI varies between RI 0.40 to 0.56. Vascularity may vary between lesions. It is higher during menstruation and in symptomatic patients⁴. Vascularity can be used as a means to decide the mode of therapy for endometriomas. Avascular lesions indicate scarification and is less convenient for delivery of medication and therefore should be considered for surgical therapy.

Kurjak et al have shown a sensitivity of 83.9%, specificity of 97.1%, PPV 82% and NPV 97.5% of vaginal sonography for characterization of endometriomas. If CA 125>35iu/ml was added as a cut off to these parameters, the sensitivity and specificity reached 99.04%, and PPV and NPV reached 98.10% and 99.82%⁵. Similar results were also confirmed by several other workers.

      Three dimensional ultrasound allows detection of surface of the endometrioma, visualization of preserved ovarian tissue and assessment of the ovarian relationship with neighbouring pelvic structures. 3D power Doppler typically shows multiple short coursed regularly separated pericystic vessels giving a typical bird’s nest appearance⁶. (figure 6)

c.Solid lesions:

      Lesions that can be included in this group are fibroma, fibrothecoma, thecoma. Brenner’s tumour etc. All except fibromas are extremely rare. Fibroma is well defined round/oval lesion with echogenecity like that of a fibroid- hypoechoic, homogenous, but sometimes may be heterogenous and may also show calcifications. (figure 7)

      Fibromas need to be differentiated from pedunculated subserosal fibroids and that cab e done by tracing the blood supply to this lesion. Fibromas are often bilateral and may also be associated with ascites and pleural effusion. This complication is known as Meig’s syndrome.

      Solid looking ovaries may also be seen in ovarian torsion. Torsed ovary is large; stroma is hypoechoic with peripherally placed small follicles. Vascularity may or may not be present and that decides the viability of the ovary. Definitive sign is a whirl pool sign in adnexa due to twisting of vessels. (figure 8). Follicular ring sign has been described as the earliest sign of ovarian torsion. This is a complete echogenic rim surrounding antral follicles⁷.

d. Complex lesions with cystic with solid areas:

Lesions in this group have thick walls, with internal echogenecities and also solid projections arising from the walls. Lesions included in this group are:

Dermoids

Epithelial tumours

Endometrioid Tumours

Dermoids

Dermoids or teratomas are often an incidental finding. These are well defined lesions with thick walls, low level echoes, fluid fluid level, hyperechoic lines and dots due to hair, hyperechoic/calcified echoes like teeth with posterior shadowing, regional diffuse bright echoes with or without acoustic shadowing due to hair clumps or fat in Rokitansky’s protuberance.(figure 9). 72% of cystic teratomas are ayascular.

These features have been assigned definite positive predictive value⁸. 80% for shadowing echodensity

     

75% for regionally bright echoes

      50% for hyperechoic lines & dots

      20% for fluid fluid level.

Positive predictive value for more than two features is 100%

      Morphologic scoring system for Dermoids by Kurjak et al has sensitivity of 93.1% and specificity of 99.4. Including colour Doppler, sensitivity of 99% and specificity of 99.8% can be achieved⁹.

Epithelial tumours:

Surface epithelial-stromal tumours account for 60% of ovarian neoplasms and 80-90% of ovarian malignancies. Of all these 46% are serous, 36.5% are mucinous and 7.5% are Endometrioid. These tumours are chiefly cystic, have septae, internal echogenecities and projections arising from its walls. Benign and malignant counterparts of these tumours have a similar but overlapping ultrasound appearances. On ultrasound, therefore it is not possible to give a histopathological diagnosis. Depending on ultrasound appearances these lesions are divided into benign, possibly malignant tumours.

Benign tumours have thin walls, (<3mm) clear contents, are usually unilocular, if septae, septae are thin and Avascular.

Whereas lesions having following features have higher chance of malignancy¹⁰.

>20cc n premenopausal patient, and >10cc in postmenopausal patient.

Cyst wall thickness >3mm and with papillarities of >3 mm.

Septae>3mm in thickness

Solid parts>1cm

Mixed or high level internal echoes

RI<0.41 can be used as a cut off for the screening of ovarian malignancy and can detect ovarian cancer as early as FIGO stage Ia¹¹. But there are pitfalls to this generalization. Variable caliber of vessels in malignant lesion may show variable resistance and velocity. Pre-existing vessels in the lesion may not show low resistance and in postmenopausal patients the resistance may not be as low as described. Therefore low resistance has a positive predictive value for malignancy but high resistance vessels do not rule out malignancy.

Chaotic vascular architecture: dichomatous branching, microaneuryms and small arteriovenous fistulae: seen on 3D power Doppler.

Bilaterality & ascites

Adhesions and disturbed relationship with structures around.

Different scoring systems have been established combining all the above mentioned features.

Using 3D US and 3D power Doppler improves the diagnostic accuracy as it is superior in evaluating¹² :

Papillary projections (niche mode)

Characteristic of cystic walls so it is especially helpful in evaluating cystic tumours (surface mode)(figure10)

Calcifications and bone densities (transparent mode)

Identifying the extent of capsular infiltration of tumors

Calculating the volume

3D PD has improved specificity (75% as compared to 54%) for ovarian malignancy and staging though the detection rate is 97.7%¹³.

Typical vascular criteria seen on 3D PD in malignant tumours¹⁴

Loss of tree branching of vessels

Sacculation of arteries and veins

Focal narrowing of arteries

Internal shift in velocity within arterial lumen

“beach ball” finding of increased and disorganized blood flow.

Increased flow to center of a solid region

Crowding of vascularity

Abruptly stopping vessels.

This advantage has improved the predictability of ovarian cancer significantly as seen in several studies. VI and VFI were significantly higher in advanced stage tumours and metastatic tumours as compared with early stage tumours.

      But 3D PD cannot differentiate between, advanced stage tumours and metastatic tumours¹⁵. 3D PD allows accurate detection of the earliest appearance of ovarian malignancy at FIGO stage 1.

      Accuracy for stage I ov Ca¹³

      2D US Abdominal               69.8%

      TVCD                          86%

      3D US                         74.4%

      3D PD                         95.3%

      3D PD+3D US                       97.7%

      Contrast enhancement on ultrasound further enables the visualization of very small vessels that were not otherwise seen. This improves the definition of small vessels in the tumour and their architecture.

      Differentiation between benign and malignant lesions by contrast induced 3D PD¹⁶.

      Sensitivity                             100%

      Specificity                                   93.9%

`     PPV                                         85.7%

      NPV                                        100%

      Further risk factors like postmenopausal age and family history of breast or ovarian cancer are also added to it, along with assessment of chemical markers for malignancy like CA 125. Though it is thought that ovarian malignancies are common in postmenopausal age there are a few very interesting and noteworthy facts about postmenopausal ovaries

      Simple asymptomatic ovarian cyst may be found in 5-17% of menopausal population. Most likely these are inclusion cysts of neoplastic cysts and may resolve spontaneously. Amongst those which do not resolve, the commonest found pathologies are serous cystadenoma, paratubal of paraovarian cysts, endometriotic cyst, mucinous cystadenoma and hydrosalpinx. Risk of malignancy in unilocular ovarian cystic tumours <10 cms size, in women >50 yrs is very low¹⁷.

      Surgery therefore should be only considered in these cases when there is a positive family history of ovarian, breast or colon cancer, high CA 125 and sonographic finding suggest malignancy.

      Tubal lesions

      Pelvic inflammatory disease (PID):

      Commonest of tubal lesions are inflammatory in origin. These lesions are usually a part of pelvic inflammatory disease (PID) and may also involve uterus and ovaries also to variable extent.

      Inflammation of fallopian tubes is known as salpingitis. Like inflammation anywhere in the body salpingitis leads to oedema and hyperemia. On ultrasound this is seen as thickened adnexa, >10mm in transverse diameter or thickened tube walls if there is fluid surrounding may be appreciated with central hyperechoic mucosa. Normally blood vessels are seen in adnexa on colour Doppler and are parallel to the long axis of adnexa. But in acute salpingits several small vessels are seen and these are not parallel to the long axis of adnexa but the run across. On pulse Doppler these vessels show low resistance (RI<0.45). In early phase of PID, ovarian parenchymal blood flow also shows low to moderate RI: 0.53+0.09, but in chronic stage it increase to 0.71+0.09¹⁸.Regression of the infection on its own or in response to antibiotic, decreases the flow in tubes and ovaries. This is usually associated with oophoritis. This appears as enlarged ovaries with hypoechoic stroma & increased vascularity.

      As this inflammation progresses towards fimbriae, it leads to adhesion of fimbriae and fluid collection in the tube, commonly described as hydrosalpinx. Patient presents with dull ache and feels ill.

      On ultrasound, extraovarian cystic lesion is seen in adnexa. On rotating the probe 90^o it changes its shape and becomes elongated. It may typically show a retort, sausage or serpinginous shape. It can be differentiated from bowel by lack of peristalsis and from a blood vessel by Doppler which shows no flow.

      It may show incomplete septae which are due to tubal haustra. (figure 11 arrow). On transverse section this tube gives a cog wheel appearance, due to fibrotic remnants of endosalpingeal tissue, or beads on string appearance on long axis¹⁹. The fluid may show low level echoes if the collection becomes thicker and also at times purulent. 3D US with inversion mode rendering is a very good tool to demonstrate such lesions.

      Extension of the inflammatory process further also may involve the ovary and also sometimes bowel or ometum in vicinity and forms tuboovarian abscess. It is seen as a complex lesion on ultrasound with low resistance (RI: 0.44+0.04)²⁰ vascularity in its solid areas and wall.

      Free fluid may be seen in pelvis. It can be separated from malignancy as patient shows signs and symptoms of acute inflammation. Abscess when heals still leaves a cyst behind or it causes fibrous scarring tuboovarian adhesions and then shows high resistance vascularity (RI: 0.75+0.04). This Doppler signals can be an important clue to differentiate it from malignancy. Tube wall that was >5mm thick in acute inflammation becomes thinner in chronic stage and the vascularity also decreases.

      Timor Tritsch et al defined the sonographic markers for the tubal inflammation²¹:                    Acute       Chronic

Thickened tube wall>5mm             100%                 3%

Cogwheel sign                               86%            3%

Incomplete Septa(92%)                

Beads on string app.                          00%             57%

(flattened / fibrotic endosalpingeal folds 2-3mm hyperechoic nodules on cross section of fluid filed structure.)

      Tuboovarian complex            36%                  2%

      Tuboovarian abscess

      Fluid Cul de sac                         50%                 10%

      Clinical evaluation and correlation is very essential to differentiate inflammatory process from neoplastic process. Though ultrasound has a very high accuracy for diagnosis of adnexal malignancies. As shown in this study…

      Detection of adnexal malignancy²²

                              Sensi.       Speci.       PPV           NPV

      TVCD              89%                98%                86%          99%

      3D+3D PD                 97%                99%                97%          99%

      Contrast 3DPD         100%        99%                93%              100%

Ectopic pregnancies:

      These are the most dreaded often missed adnexal lesions. By definition, an ectopic pregnancy is an implantation of gestational sac in a place other than the endometrial cavity. It can be in the fallopian tube (95%), abdominal cavity, ovary, broad ligament, uterine cornu, myometrium or cervix. Though we shall here discuss only tubal and ovarian ectopic pregnancies.

      Salpingitis and PID significantly increases the risk of ectopic pregnancy.

      Patient presents with a period of amenorrhoea, positive urine pregnancy test or positive b hCG for pregnancy, with vaginal spotting and irregular vaginal bleeding abdominal pain, vasomotor shock and fainting attacks. On examination she will have tenderness in fornices. Patient may be stable but may show hypotension and tachycardia if this pregnancy invades through the tube wall.

      Ultrasound is considered to be the gold standard for diagnosis of ectopic pregnancy.

On ultrasound:

      Uterus: shows no gestational sac in endometrial cavity even when b hCG levels are>1000iu. Uterus may or may not show increased endometrial thickness due to decidual kike reaction. Pseudo gestational sac may be seen. It can be differentiated from true gestational sac by its situation in the centre of the uterine cavity, absence of the double decidual sign, change in shape with uterine contractions and absence of perisac vascularity.

      Adnexa: show mass, separate from ovary. It may be homogenous or heterogenous, may or may not show gestational sac in early phase and shows a ring of vascularity with low resistance, high velocity blood flow. Ipsilateral corpus luteum is seen. Adnexal mass must be differentiated form corpus luteum, heamorrhagic cyst or any other complex mass.

      Volume ultrasound can especially be useful for early diagnosis of tubal pregnancy because it shows symmetry of the uterine cavity in ectopic pregnancy and distended fallopian tube, with thin hypoechoic border.

      Symmetry of the endometrial cavity in frontal plane is seen in 90% of extrauterine pregnancies. (it is asymmetrical in 84% of normal pregnancies)²³. 3D power Doppler cab also be used for follow up of these pregnancies. Decreasing VI, FI and VFI values (3D power Doppler indices), suggest that this pregnancy can be treated conservatively or vice versa.

      Free fluid is seen in pelvis mostly only if bleeding has occurred because of invasion of tubal wall.

      Ovarian ectopic pregnancy is rare. But should be differentiated from corpus luteum. Both the lesions show similar morphology and ring of vascularity with low resistance flow. It is the echogenecity of its thick walls surrounding the anechoic centre that gives a clue to the diagnosis. This wall is isoechoic in corpus luteum but is significantly hyperechoic (like that of decidual reaction in uterus) in an ovarian ectopic pregnancy.

Miscellaneous lesions:

Broad ligament fibroid

Peritoneal inclusion cyst

Paraovarian cyst.

Board ligament fibroid: this is a fibroid arising from broad ligament. On ultrasound it is a well circumscribed, usually round, hypoechoic lesion. It can be separated from both uterus and ovary by probe pressure and shows peripheral vascularity.

Peritoneal inclusion cyst: is a fluid collection in the pelvic peritoneum with septations. This fluid collection is not under pressure and therefore changes shape on probe pressure. The septae inside, move with respiration, pressure or with pulsations of nearby vessel. These lesions typically do not show any vascularity.

Paraovarian cyst: Upto 20% of adnexal masses may be paraovarian cysts. These are benign, avascular lesions with thin walls and anechoic contents. The shapes does not change with pressure but can be easily separated from ovary. Adhesions indicate infection and solid projections in it may raise a possibility of malignancy.

Ultrasound is a very efficient tool for assessment of adnexal lesions. With advent of new ultrasound technologies, Doppler, 3D US, 3D power Doppler and contrast enhanced ultrasound, this efficacy has further increased.

Pelvic US is especially important to decide the site of origin of the lesion, differentiation of pathological and physiological lesions and for differentiation of benign from malignant masses which will help decide the line of treatment. Ultrasound is also useful for management of some of these lesions e.g. for cyst aspirations or biopsies under ultrasound guidance.

Cycle assessment by ultrasound

Introduction:

      Treatment of infertility needs a thorough assessment of the hormonal changes occurring during menstrual cycle in a female and therefore evaluation of the complete cycle instead of only pre hCG scan is essential. This consists of three scans: baseline scan preovulatory scan and secretory scan.

      Route of scan has to be transvaginal always. Using transabdominal approach for ovarian assessment may miss at least 42% of the ovarian anatomical details.¹ All scans are done using not only B mode or 2D ultrasound(US) but also with colour Doppler, pulse Doppler, 3D ultrasound and 3D power Doppler. Using colour Doppler in this assessment is mandatory because a large number of biochemical or hormonal changes occur during the cycle, and these reflect as vascular and morphological changes in ovaries and uterus and these vascular changes can be assessed by Doppler. 3D ultrasound is especially useful for volume measurements. 3D power Doppler has also been proved to be highly promising in several studies, as it gives idea about the global vascularity of the structure examined.

Baseline Scan:

      This scan is done on 2^nd or 3^rd day of the cycle. It is known as a baseline scan because at this time of the cycle, the ovaries have no active follicles, oestrogen and progesterone are both at lowest levels, endometrium is thin like a single line as it has shed off during menstruation and this is an absolute baseline status of the ovaries.

      This scan consists of transvaginal sonography TVS, transvaginal Colour Doppler (TVCD) and volume US of ovaries and uterus. It is done to classify the ovaries in one of the four categories: Polycystic ovaries (PCO), normal ovaries, low reserve ovaries and poorly responding ovaries or in other words to predict the ovarian reserve and response which can guide to decide the stimulation protocols for ART. Uterus is assessed for the procedure: intrauterine insemination (IUI) or embryotransfer (ET), and for receptivity.

Baseline scan of Ovaries:

      2D ultrasound assessment of the ovaries consists of assessment of ovarian diameters and volume, counting of antral follicles and quantitative & qualitative assessment of stromal abundance. Colour of power Doppler is used to see the presence of vessels in the stoma and pulse Doppler is used for quantitative assessment of the flows – intraovarian resistance index (RI) and peak systolic velocity (PSV). Then 3D and 3D power Doppler volume of the ovary is acquired for ovarian volume and stromal volume & counting the number of antral follicles. Global vascular indices VI (vascularity index), FI (flow index) and VFI(vascularity flow index) may be calculated by volume histogram. VI indicates abundance of flow in the calculated volume. FI indicates average intensity of flow and VFI indicates perfusion of this volume.

Normal ovaries have:

            Diameter:                             2-3.5 cms

            Volume:                          3-6.6cc

            Stromal RI:                     0.6-0.7

            Stromal PSV:                        5-10 cms/sec

            Antral follicle count:                 5-12 per ovary

US and Doppler features for Polycystic ovaries (PCO)

      Enlarged ovaries, multiple antral follicles, stromal abundance and atypical endometrium are features of polycystic ovaries as described in literature. But each of the features needs to be evaluated independently. According to Rotterdam criteria (ESHRE/ASRM 2003 consensus) polycystic ovarian syndrome is defined as²:

      Two of the following three criteria and exclusion of other etiologies:

Oligo and/or anovulation

Hyperandrogenism

Polycystic ovaries

According to this definition polycystic ovary on ultrasound is ovary that is>10cc in volume and/or has>12 antral follicles.

Enlarged ovaries:

      On 2D US an ovary which has a longest diameter of>3.5 cms is considered enlarged. When scanning the ovary, the probe rotated at various angles to find out the most longitudinal section of the vary. To calculate the volume of the ovary on 2D US a second section is taken by rotating the probe 90^o from this most longitudinal section. On this section two perpendicular measurements are taken one perpendicular and one parallel to the ultrasound beam. Volume is calculated by applying the formula (x x y x z) x 0.523. Calculation of ovarian volume by VOCAL (volume calculation by computer: virtual organ computer aided analysis) on 3D US is much more accurate. For VOCAL usually rotating angle of 30^o is used but in case of an ovary which is not perfectly oval, angle of 15^o may be preferred.

      According to Rotterdam criteria ovarian volume of 10 cc is a criteria for polycystic ovarian disease. “For an ovarian size of 10cc a good correlation has been shown between ultrasound diagnosis of polycystic morphology and histopathological criteria for polycystic ovaries.”³It is important to note here that this has been specified for polycystic ovarian syndrome, which is a clinical entity and therefore is based on clinical as well as ultrasound features.

      The interpretation here would be, according to the above quoted reference, that if a patient has an ovarian volume of 10 cc or more, she has to have clinical features of polycystic ovarian syndrome (PCOS). But reports have also shown that an ovarian size of 6.6 cc has 91% sensitivity and 91% specificity for PCOS.⁴ And yet another report says “However, ovaries which are normal in volume can be polycystic as demonstrated by histological and biochemical studies. (in 20%)”⁵ This means ovarian volume alone can not be used as the criteria for diagnosis of PCO.

      Polycystic ovarian morphology has been found to be a better discriminator than ovarian volume between polycystic ovarian syndrome and control women.⁶

      These morphological features are multiple antral follicles, follicular arrangement and predominant stroma.

Multiple immature follicles (2-9mm)

Counting antral follicles especially in PCO patients is difficult on 2D ultrasound. There is a high chance of over or undercounting because of multiple follicles and therefore has low interobserver and intraobserver reliability. If 3D volume of the ovary is acquired and then is rendered in inversion mode or Sono AVC (automatic volume calculation) is used the antral follicle count can be reliably done. Sono AVC colour codes each follicle and on report sheet presents diameter and volume of each follicle. Using Sono AVC for counting antral follicles requires postprocessing.

12 or more antral follicles of 2-9 mm size has also been quoted as one of the ultrasound features of PCOS. But this number has been reported to vary from 5-15 in different reports. Though setting the threshold at 12 for 2-9 mm FNPO (follicular number per ovary) offered the best compromise between specificity (99%) and sensitivity (75%).⁷ But females in adolescence have multiple follicles in the ovary and these are not all PCOS patients. These controversies can be explained if we go through the evolution of PCOS.

Evolution of PCOS:

      Elevated androgen leads to recruitment of multiple follicles in the ovaries. But all these follicles do not become dominant. The antral follicles produce oestrogen and excess androgen also is converted to oestrogen. These lead to high oestrogen levels in absence of mature follicle. This gives negative feedback to FSH, which interferes with follicular growth, and a positive feedback to LH, which causes leuteinization of these immature follicles and follicular atresia, with conversion of granulose cells to theca cells that contribute to stroma.⁸ In the early phase of the disease the stroma becomes denser in parts and when anovulation continues, whole stroma becomes echogenic, leading to a generalize cystic pattern (GCP) of PCO. As the disease progresses, follicles are pushed to the periphery and then not only the stromal density but the stromal volume also increases, leading to enlargement of the ovary leading to peripheral cystic pattern (PCP) of PCO. This means that from multicystic cystic ovaries i.e. ovaries normal in size having multiple follicles of various sizes and normal stroma- which is a normal appearance in adolescence to GCP PCO and PCP PCO is a process of evolution as a result of high basal androgen levels and chronic anovulation in these females. This explains not only the variability in the size of the ovaries but also the variability  in the number of antral follicles in PCOS patients having oligo-ovulation and Hyperandrogenism.

Predominant hyperechoic stroma

      Stromal abundance therefore is the most reliable and key factor for the diagnosis of PCOS. This abundance can be known by increased stromal echogenecity. Polycystic ovaries show a hyperechoic stroma but assessment of this hyperechogenecity is subjective not only to the operator but also to equipment settings.^10,11 Therefore a more objective or reproducible criteria is required for assessment of stromal density and this is done by measuring ovarian area and stromal area on 2D ultrasound and ovarian volume and stromal volume on 3D US. Ovarian area of 5.3 cm² on strict longitudinal ovarian section and stromal area of 4.6 cms² has high sensitivity and specificity for PCOS.⁴ But stromal area/ovarian area ratio has been found to be even more efficient for diagnosis of PCOS.

      Sensitivity for diagnosis of PCOS¹²

Ovarian volume      13.21 cc        21%

Ovarian area                  7cm²              4%

Stromal area                  1.95cm²              62%

Stromal/total area       0.34                100%

Stromal volume can be calculated by acquiring a 3D volume of the ovary and calculating the volume by VOCAL and then using threshold volume, adjusting the threshold to exclude the follicles from total ovarian volume. This helps to separately calculate the volume of the structures below the threshold (follicular volume) and above the threshold (Stromal Volume).

Stromal volume to ovarian volume ration of >75% in an ovary which is either >6.6cc or has > 12 antral follicles was found to be diagnostic of PCOS in a study of 500 PCOS patients assessed at our centre.(unpublished data)

Apart from these major features, PCOS patients show atypical endometrium or out of phase endometrium due to the hormonal derangements like high LH and early rise of oestrogen due to multiple follicle recruitment and conversion of androgen to oestrogen. For these reasons, endometrium in early follicular phase appears multilayered in PCOS patients and becomes echogenic just before ovulation

.

      It has also been observed by some workers that right to left ovarian volume ratio is reversed in PCOS patients. In control patients left ovary is larger than left and in PCOS patients right ovary is larger.⁴

      There are certain Doppler characteristics of the PCO. These ovaries show stromal flow on the baseline scan. When colour box is placed on the ovary the blood vessels in the stroma only are to be picked up for quantitative assessment. Vessels close to the developing follicles are not stromal vessels. On pulse Doppler these vessels show RI: 0.50-0.58.¹³ This is because of high LH levels. If these blood vessels also show a PSV of >10cms/sec, ovary is prone to hyperstimulation. High androgen levels in these patients also lead to high uterine artery pulsatility index (PI).

      It is interesting to note here that higher uterine artery PI and lower ovarian stromal vessel resistance is seen in PCP ovaries than GCP ovaries, higher age, amenorrohic, rather than oligomenorrhic patients and in obese, hyperinsulinemic and hirsuit patients.

      FNPO in the range of 6-9 mm was significantly and negatively related to body mass index and fasting serum insulin level.⁷

US features of Polycystic ovaries:

Longest diameter>3.5cms

Ovarian volume>6.6cc

More than 12 antral follicles

Hyperechoic, predominant stroma

Intraovarian stromal flow present

Intraovarian stromal RI 0.50 0.58

Intraovarian stromal PSV 10cms/sec or more

High uterine artery PI

Atypical endometrium

Stromal area: ovarian area ratio>0.34

Stromal volume: Ovarian volume ratio>75%

Remember all features can not be seen in all the patients.

Third type of ovaries are poorly responding ovaries. These may be any size but have intraovarian stomal RI>0.68, and PSV<5cms/sec. they have low vascularity and therefore respond only to higher doses of stimulation.

Fourth type is low reserve ovaries which are small sized ovaries with<2 cms longest diameter or <3cc volume and have <3 antral follicles. They will produce very few follicles with any stimulation.

Actually any ovary has one feature from each of these two following groups:

Low reserve, normal reserve and polycystic ovary.

Low response, normal response and hyperresponse.

Based on this, predictors of ovarian response are.¹⁴

Number of antral follicles

Ovarian stromal FI

Total ovarian stromal area

Total ovarian volume

In that order of importance.

Antral follicle count is a better marker than basal FSH for selection of older patients with acceptable pregnancy offer¹⁵. Antral follicle count and ovarian volume showed significant correlation with AMH, total testosterone and free androgen index¹⁶.

Precise calculation of antral follicle count therefore helps in predicting the ovarian response. This can be done on 2D ultrasound by scanning across the whole ovary while counting the follicles by eyeballing. But this has high chances of error when follicles are multiple as in polycystic ovaries.

 In these cases counting the antral follicles by 3D US is much more precise. After taking a 3D volume of the ovary and doing a VOCAL for it, the ovary is rendered in inversion mode. This clearly shows all the follicles as solid balls and by rotating them they can be counted fairly accurately. A more precise method is using Sono AVC (automatic volume calculation). And this has been described earlier. Antral follicles when counted by inversion mode: One is likely to get 60% of follicles of the counted antral follicles in IVF cycles.¹⁷

SonoAVC with postprocessing(PP) is a reliable method for measuring total AFC. It takes longer to perform, because of the need for postprocessing, and obtains values that are lower than those obtained by the 2D and 3D-MPV techniques. However, the AFC obtained by SonoAVC-PP is likely to be lower because this method measures and color codes each follicle preventing recounting. Intraobserver and interobserver reliability of automated antral follicle counts made using three-dimensional ultrasound and SonoAVC a preferred method.¹⁸

It has been shown by Zaidi et al that stromal blood flow velocity after pituitary suppression was an independent predictor of ovarian response.¹⁹

Kupesic has shown correlation in the ovarian stromal flow index and number of mature oocytes retrieved in a IVF cycle and pregnancy rates¹⁴.

Baseline scan of Uterus:

      Base line scan of the uterus is done to assess the uterocervical length by ultrasound. Longitudinal section of the uterus is imaged on the screen where whole of the uterus is seen with endometrial cavity starting from fundus to the internal os and external os. For all ART procedures may it be intrauterine insemination(IUI) or embryo  transfer(ET),  the uterocervical length is measured from the fundal end of the endometrium to the external os and is known as functional or physiological uterocervical length. Doppler of the uterine artery is done. Uterine artery RI>0.79 indicates that high doses of stimulation will be required for endometrial maturation²⁰.Subendometrial flow on day 2 if is present indicates a low receptive endometrium for implantation. This is so because on day 2 ovaries are silent, oestrogen level is very low and therefore no endometrial vascularity is expected normally. If it is present it is either high basal oestrogen or inflammation of the endometrium leading to increased vascularity.

Preovulatory scan:

      We know that not all antral follicles grow to become dominant and mature follicle. A follicle that grows to 12mm is a dominant follicle, it grows at a rate of 2-3mm/day and ovulation occurs at 18-24 mm size usually. Follicular flow can be first detected when follicular size is 10mm²¹ and its resistance starts falling two days to ovulation.

Features of a mature follicle:

      A rounded 16-18 mm sized follicle with thin walls and no internal echogenecity is expected to be mature. A sonolucent halo appears surrounding the follicle, 24 hours prior to ovulation. Cumulus oophorus a small projection from wall in the follicular lumen may be seen.

      On colour Doppler vascularity is seen surrounding 3/4^th of the follicular circumference. On pulse Doppler these vessels show RI 0.4-0.48²²,PSV >10 cms/sec. This flow indices are of perifollicular vessels and perifollicular vessels are the ones that overlap the follicular wall. If the follicular vascular indices are not in the defined range, it means that the follicle is not yet physiologically mature and therefore stimulation still needs to be continued. 24 mm is the follicle size till which one can wait for the optimum flows to be achieved.

      This means that if the follicle is said to be functionally mature when PSV is 10 cms/sec, that is the time when the LH surge starts and under the effect of that LH, the perifollicular PSV keeps on rising constantly. Follicular blood flow velocity starts increasing app. 26-29 hours before rupture and continues till 72 hours after rupture. The perifollicular PSV rises as high as 45cms/sec before an hour of ovulation.

      We have done a study of 500 IUI cycles based on this to find out appropriate time of IUI based on pre hCG perifollicular vascularity. Single IUI was done between 36-38 hours and double IUI were done at 12-14 hours and 36-38 hours after hCG in all patients in whom perifollicular PSV >15 cms/sec. When perifollicular PSV on the day of hCG was more than 20 cms/sec, and perifollicular RI was within normal range, double IUI has given significantly higher pregnancy rates.²³ This indicates that in patients with higher perifollicular pre hCG PSV, IUI done at 12-14 hours has been fruitful. In the course of time after larger study that is ongoing we would plan to omit the second or the later IUI in patients in whom pre hCG perifollicular PSV is more than 20 cms/sec.

      Fertilization of a follicle with a PSV of less than 10cms/sec, have high chances of embryo with chromosomal abnormality.

      Rising PSV with steady low RI suggests that the follicle is close to rupture²¹. Steady or decreasing PSV with rising RI suggests that the follicle is proceeding towards LUF²⁴.

Application of 3D US for follicular assessment:

      When there is multifollicular development as in PCO the follicular shapes become polygonal and therefore follicular diameter may not be a reliable parameter. Follicular volume by 3D is a more reliable parameter. Follicular volumes of between 3-7 cc are optimum for oocyte retrieval. The limits of agreement between the volume of the follicular aspirate and 3D volume of the follicle were + 0.96 to 0.43 with 3D and + 3.47 to-2.42 by 2D volume estimation²⁵.

      Cumulus can be seen in almost 90% of follicles using 3D US rendering. This is possible only in upto 40-45% follicles by 2D US. On the day of hCG, if cumulus like echo is not seen in all three planes in the follicle, it is less likely to be mature fertilizable oocyte²⁶.

      3D power Doppler gives idea about the global vascularity of the follicle. The 3D power Doppler indices, VI, FI and VFI give quantitative global assessment of vascularity. We have done a large study taking this into consideration. Based on study of >1000 cycles²⁷, follicular volume of 3-7.5 cc, VI>6-20 and FI>35 if used as additional features for a mature follicle apart from the follicular features mentioned previously, increased the pregnancy rate significantly²⁴.

Features of mature follicle

Minimal follicular diameter of 16mm for gonadotrophin stimulation

Minimal follicular diameter of 18mm for CC stimulation

Perifollicular flow-3/4^th circumference

Perifollicular RI 0.40-0.48, PSV>10cms/sec

Cumulus Oophorus

Follicular volume 3.75 cc

Follicular VI 6-20, FI>27 (preferably>35)

Features of a mature endometrium:

      On 2D ultrasound an endometrium of 6mm or more in thickness, preferably 8-10 mm that is multilayered is good enough. But its morphological assessment is essential. Because of orderly organization of glandular elements in proliferative phase, endometrium is generally hypoechoic in this phase, though the morphology can be graded as follows.

Endometrial grading

      Grade A Endometrium: Multilayered with intervening area more echogenic than myometrium

      Grade B endometrium: Multilayered with intervening area hypoechoic to myometrium

      Grade C Endometrium: Homogenous hyperechoic endometrium B mode ultrasound assesses the anatomy of the endometrium but its functional maturity can be assessed by Doppler of spiral arteries.

      Spiral arteries supply the endometrium and these are the vessels that undergo substantial changes during menstrual cycle. Oestrogen causes vasodilatation and progesterone antagonizes the effect. Therefore higher E2/P ratio is responsible for higher blood flow through uterine vascular bed. Thus endometrial colour Doppler gives direct information about oestrogen and progesterone levels and in turn also about functional maturity of the follicle and endometrium.

      On colour Doppler, the vascularity of the endometrium is classified by Applebaum as follows²⁹.

      Zone I Blood vessels reaching myometrium surrounding the endometrium

      Zone II Blood vessels reaching hyperechoic endometrial edge

      Zone III-Blood vessels reaching internal endometrial hypoechoic zone.

      Zone IV Blood vessels reaching endometrial cavity.

      On pulse Doppler, these blood vessels should show RI 0.49-0.59 and PI 1.1-2.3. This vascularity should cover 5mm² area of a particular (3-4) zone of endometrium.

      Even if TVCD of follicle is normal, endometrial and the uterine artery indices should be within normal limits for implantation. Therefore even with mature follicle if endometrial vascular parameters are not achieved, stimulation is to be continued. Absent subendometrial and intraendometrial vascularization on the day of hCG, appears to be a useful predictor of failure of implantation in IVF, irrespective of morphological appearance³⁰.Conception rates according to zones of vascularity in two different studies are quoted as

Zone 1           3.5%-7.5%          5.2%

Zone 2           15.8%-29.7%            28.7%

Zone 3           24.2%-47.8%            52%

Zone 4           67.3%             74%

It has also been observed that when pregnancy is achieved in absence of endometrial and subendometrial flow on the day of embryo transfer, more than half on these pregnancies will finish as spontaneous miscarriage³¹. Though it has been observed that spiral arteries have higher PSV and lower resistance in natural cycles as compared to stimulated cycles, may it be Clomiphene citrate of gonadotrophins.

      Apart from endometrium and follicle it is also essential to evaluate the uterine artery flow on the dominant side before hCG. Oestrogen receptors are present in uterine arteries and cause vasodilatation in these vessels also. The normal values of uterine artery indices are RI 0.60-0.80 and PI 2.22-3.16²⁹. Even if TVCD of follicle is normal, endometrial and the uterine artery indices should be within normal limits for implantation. Embryo transfers in IVF cycles are also cancelled if the uterine artery PI>3.2.³² hCG  administration induces significant increase in the resistance of uterine artery for 48 hours which can affect its evaluation on the day of follicular aspiration/rupture therefore Doppler study for uterine receptivity should be done on the day of hCG²⁰. Moreover the Doppler studies are better done at the same time every day as circadian rhythm is seen in uterine artery flow in periovulatory phase.

      As for the follicle, the endometrium also if evaluated by 3D and 3D power Doppler for maturity before hCG, gives better implantation rates. It gives endometrial volume instead of endometrial thickness. When we measure endometrial thickness, we measure it at the thickest part, and this thickness might not be uniform in the whole endometrium. Moreover some times in spite of normal thickness the length of the endometrial cavity may be so short that the total endometrial volume is not enough for implantation. Therefore volume is considered to be a better parameter than endometrial thickness. More over 3D power Doppler gives idea about the global vascularity of the endometrium not only in terms of quality but also in terms of quantity, which should be a more useful parameter than 2D Doppler where we can see vessels only in one plane at a time and also interrogate a few vessels, not all by pulse doppler. In our study²⁷, 3D power Doppler indices that we have found reliable are endomentrial volume> 3cc, FI>5. There are several other people who have also worked on endometrial receptivity assessment by 3D and 3D power Doppler. A study by Luis T Merce et al of 40 IVF cycles has shown endometrial volume of 3-7 ml as most favourable for conception. Median values for a favourable endometrium is 4.28 + / - 1.9ml.³³

      Endometrial volume of>2.0ml has a significantly higher pregnancy rates and no pregnancies were recorded with endometrial volume of<1ml³⁴.

      Another study showed that pregnancy occurred when endometrial volume <3ml and VI <10. Exceptionally better pregnancy rates are achieved with endometrial volume>7ml and subendometrial VI between 10-35%³³. A study by Kupesic et al shows lower resistance index of 0.49-0.57 in subendometrial vessels and FI of 11.0-15.4 in conception cycles as compared to 9.5-13.3 otherwise³⁵.

      VFI on the day of hCG is more sensitive than volume, VI and FI for prediction of pregnancy. VFI>0.24 has

      - sensitivity of 83.3%

      - specificity of 88.9%,

      - PPV 93.8%

      - NPV 72.3%

For prediction of pregnancy with 33% pregnancy rate.

      Scoring system has also been developed for endometrial receptivity, which apart from the endometrial thickness, morphology, vascularity and uterine artery Doppler also includes uterine contraction count. Calculating contractrions/mt, >5/mt is considered unfavourable foe implantation and <3 contractions / minute is considered good for implantation. This is purely based on the fact that uterus that is highly contractile and irritable, will not allow implantation, and the one that is pacified by progesterone may have better chances of implantation. This may also be one of the causes for better implantation rates for blastocyst transfer. Though this scoring system is not practically applicable as even with full scores of the often used uterine scoring systems, pregnancy might not occur.

      Features of mature endometrium

Minimum thickness of 6mm, preferably 8mm

Grade A endometrium

Vascularity reaching zone 3-4

Endometrial RI 0.6-0.8

Endometrial volume 3-7 cc.

Endometrial FI> 20, VFI>5

Uterine artery PI<3.2

Secretory Scan:

      With the rupture of the follicle corpus luteum is formed. Corpus luteum is a cystic structure with thick shaggy walls and echogenecity in the lumen. But it is known to have variable appearances like ground glass echogenecity in lumen or lace like echogenecities. Secretory changes are seen in the endometrium in the form of echogenecity of the endometrium which starts from outside, proceeding to the central line making a ring sign of the endometrium³⁷. Posterior wall of the uterus also appears more echogenic in this phase due to acoustic enhancement by the endometrium due to fluid accumulation.

      Assessment of the corpus luteum, endometrium and uterine artery by Doppler gives information about the luteal phase normalcy and progesterone levels. A clear correlation between RI of corpus luteum and plasma progesterone levels has been seen in natural cycle. RI of the corpus luteum can therefore be used as an adjunct to plasma progesterone assay as an index of luteal function³⁸.

      A healthy corpus luteum will show a vascular ring surrounding itself on colour Doppler and on power Doppler these vessels show RI 0.35-0.50, PI 0.70-0.80 and PSV 10 15cms/sec^24,29. This resistance starts increasing on day 23 of the cycle in a nonconception cycle to RI 0.5-0.55. Endometrial Doppler shows branches of spiral arteries piercing the outer echogenic margins of the endometrium and better if it reaches the central line with RI of 0.48-0.52. Uterine artery at this time of the cycle has PI of 2.0-2.5 and PSV 15-20cms/sec. Based on these values abnormal parameters indicate luteal phase problems like luteinized unruptured follicle or luteal phase defect.

      On 2D US shows persistent follicle with thick walls and progressive loss of cystic appearance which is difficult to differentiate from corpus luteum. Endometrium is thick and echogenic and no fluid is seen in POD. On Doppler perifollicular RI is 0.51-0.59, which is higher than normal and remains almost same till the end of the cycle. Nondominant ovary also shows similar Doppler indices. Endometrium is echogenic but endometrial flow is absent²⁴.

Luteal phase defect:

      In this case there is normal follicular development and ovulation with early secretory transformation of endometrium. On Doppler corpus luteum shows high resistance flow with RI: 0.58+0.04. Bilateral ovarian RI shows no difference that means there is no difference in vascular resistance in dominant and nondominant ovary. Increased resistance is also seen in spiral arteries RI: 0.72+0.06⁴⁰. This is the case when luteal phase defect is due to insufficient corpus luteum. But when luteal phase defect is due to insufficient progesterone receptors in the endometrium, the endometrial flow is normal but endometrium is thin, nonhyperechogenic and shows scanty vascularity.

      Increased resistance of uterine blood flow in the midluteal phase may be an important contributing factor to some causes of infertility and the cause of some previously “unexplained” infertility⁴¹.

      Segmental uterine and ovarian artery perfusion demonstrate a significant correlation with histological and hormonal markers of uterine receptivity and may aid assessment of luteal phase defect.

      As quoted by Golan et al and Tan SL et al

      “In the hands of experienced operators, ultrasound alone suffices for cycle monitoring, with no necessity for additional hormonal estimations.”

Fetal Screening for chromosomal anomalies

      All the fetuses that have an abnormality in their genetic configuration are bound to show some structural abnormalities and since about last few years the awareness for detecting such features has increased.

      As seen in sonoembryology, at 12-13 weeks the fetus is a fully developed human being and naturally therefore, if only one scan is to be done in the first trimester to detect abnormalities, it should be done after 10 weeks, preferably 11-12 weeks.

Why is this scan mandatory?

      It has been studied that the risk of chromosomal abnormalities increases as the maternal age advances and is very high if the maternal age is more than 35 years, and are considered a high risk group. But that does not mean that only the fetuses of the mother of 35 years of age or more are at risk, because as seen in the graph, only 30% of the babies having Down’s syndrome have been born to the mothers of more than 35 years of age. This clearly means that 70% of the Down’s babies are born in the low risk group mothers.

      Down’s or any other chromosomal abnormalities can be most confidently diagnosed by invasive testing like amniocentesis and chorion villous biopsy followed by chromosomal study. But these invasive tests have 1% risk of abortion. More over being invasive can be offered only to the high risk mothers, which means detecting only 30% of Down’s babies. So if this method was preferred 70 % of the Down’s babies will be missed on antenatal screening.

      Another screening test which could still be offered to a larger mass is a triple marker test, done between 15 and 22 weeks of gestation. This has a sensitivity of only 65-70%¹

      Naturally an investigation which would have a much higher sensitivity, is noninvasive, can detect aneuploidies early and can be offered for a large mass was sought for.

      In early 90’s some subtle anatomical variations were detected in the fetuses with chromosomal abnormalities. Though these subtle variations could be detected in about 2% of normal fetuses their frequency was very high in fetuses with aneuploidies and were called markers for aneuploidies. Based on this knowledge of markers a detailed scan was designed that could be best done between 11-13+6 weeks for detection of aneuploid fetuses and was called a Genetic scan.

      By definition, a genetic sonogram is defined as an ultrasound scan that can modify the a priori risk of fetal aneuploidy, typically based on a panel of ultrasound markers.

      This scan is done for detection of

Major structural anomalies in aneuploidies

-Compatible with life

-Incompatible for independent existence

Chromosomal markers

-Most indicative or major markers

-Soft markers.

      Structural abnormalities that must be looked for and are detectable on early 2^nd trimester scan can be listed as follows:

Cranial abnormalities

  Holoprosencephaly

  Spinabifida

  Anencephaly and/ of acrania

Facial abnormalities

Cleft palate

Ocular abnormalities

Micrognathia

Short ears

Cardiovascular abnormalities

Abdominal abnormalities

   Diaphragmatic hernia

   Duodenal atresia

   Omphalocoele

   Megacystitis

 Limb reduction abnormalities

 Hydrothorax-ascites

Cranial anomalies-

Holoprosencephaly:

This abnormality is complete or partial deficiency of falx leading to alobar, semilobar or lobar type of Holoprosencephaly. Later is the mildest form and often not diagnosed till late pregnancy and also has least neurological implications. Whereas alobar is the most extensive defect leading to severe neurological deficits and cab be diagnosed as early as 12 to 14 weeks. This shows single spherical cerebral structure, with single common ventricle, posterior large cyst of third ventrical known as dorsal sac, absent olfactory bulbs and tracts and single optic nerve. Septum pellucidum is always absent with midline fusion of cingulated gyrus and frontal horns of lateral ventricles. These have flat roof and freely communicate with third ventricle.

40-60% of the holoprosencehalic fetuses have chromosomal abnormalities, of which 50% are Trisomy 13. Of those which are euploids 90% have facial abnormalities and 70% have other structural abnormalities². Alobar and semilobar Holoprosencephaly are more likely to be associated with aneuploidies, rather than lobar ones.

This abnormality is often associated with facial dysmorphism including midline facial defects.

Acrania/exencephaly and anencephaly:

Acrania is totally nonossified skull vault bones and exencephaly is partially nonossified skull vault bones. Ossification of the skull bones starts and accelerates at 9 weeks of gestation. Acrania can therefore be diagnosed after 11 weeks. The brain matter lies free in the amniotic cavity and shows abnormal shape of the head due to disintegration of brain matter. Typical shape is described as ‘Mickey mouse’ head when majority of the brain matter is disintegrated.

Smaller defects in skull vault with herniation of the meninges or brain matter is described as cephalocoeles.

Anencephaly is total disintegration of brain matter and appearance is described as frog face as the orbits become the most protruding structures. There is no forehead or culvarium.

Iniencephaly

      This is a lethal anomaly with defect in occiput, involving foramen magnum, retroflexion of entire spine, star gazing fetus and open spinal canal defects of variable degrees. Associated abnormalities like hydrocephaly, microcephaly, ventricular atresia, Holoprosencephaly are known. It may also be associated with diaphragmatic hernia, urinary tract abnormalities, cleft lip and palate, Omphalocoele and thoracic cage abnormalities with polyhydramnios.

6) Dandywalker’s malformation:

      32% of the fetuses having Dandywalker’s malformation have chromosomal anomalies, most commonly in Trisomy 18 & 13³. Amongst the fetuses having Dandywalker’s variation also 53% have chromosomal anomalies. Cerebellar hypoplasia may also be associated with aneuploidies. The risk is higher when Dandy Walker malformation or variation is detected at an early gestational age. An enlarged cistern magna though may be seen with normal fetuses, especially in males and after 26 weeks⁴. It is likely to indicate Trisomy 18 if seen in third trimester and is associated with polyhydramnios and IUGR.

      Dandy walker malformation is also seen in inheritable syndromes like Ellis-van Crevald syndrome, and Meckel Gruber syndrome.

Spina Bifida & Hydrocephalus:

Spina bifida is commonly associated with lemon sign, or banana sign in 2^nd trimester. 14% fetuses with spina bifida have aneuploidy, most commonly trisomy 18, 13, triplody and translovation⁵. Hydrocephalus is a common association. 22% of the fetuses with chromosomal anomalies may present only with spina bifida and hydrocephalus in first trimester.

A more reliable sign for open spinal canal defects is measuring intracranial translucency (IT). This requires the same section as that for nuchal translucence and therefore we shall discuss it later in this chapter.

Facial anomalies

      The midline facial anomalies especially with holoprosecephaly are commonly associated with trisomy 18 and 13 and so when ever found; detailed study for chromosomal abnormalities is mandatory. Facial abnormalities are best diagnosed by volume ultrasound, rendered imaging as coronal view of the face is required which is more easily obtainable on 3D.

Cleft lip and palate:

      Lip becomes continuous at 8 weeks and therefore a cleft can be diagnosed at 11-14 weeks scan. The chances of aneuploidy with cleft palate are - 20-30% in unilateral cleft palate (more common on left side and in females)

      - 30 50% if bilateral cleft palate

      - 50 80% if median cleft palate

      Isolated cleft lip without a cleft palate is not commonly associated with aneuploids⁶.

Ocular abnormalities:

      Cyclopia (single orbit in the centre), hypotelorism (closely placed orbits) or hypertelorism (widely placed orbits) are associated with trisomy 13, 18 and nonchromosomal syndromes.

 Micrognathia (receding small chin) may be an indicator of trisomy 18 or triploidy.

Short low placed ears are typically associated with trisomies 21, 18, 13 and have similar value as increased nuchal translucency in detection of fetal aneuploidies. But these are not easy to diagnose on b mode ultrasound and so are not included in major markers. Though volume ultrasound can demonstrate is very well.

Prominent occiput may be seen in trisomy 18 fetuses.

Cardiac abnormalities:

      22-32% of fetuses with cardiac anomalies have chromosomal anomalies⁷. Only 0.1% of euploids neonates have cardiac abnormalities but 13% of the aneuploid neonates have cardiac abnormalities.

      Atrioventricular septal defects (AVSD), VSD, Ebstein’s anomaly, Fallot’s tetralogy and hypoplastic left heart are often associated with aneuploidies⁸.Ectopia cordis only when associated with pentology of Cantrell, is associated with trisomies. (Pentology of Cantrell, Median supraumbilical abdominal defect, defect in lower sternum, defect of diaphragmatic pericardium, defect of anterior diaphragm, intracardiac abnormality).

      Isomerism, transposition of great arteries, pulmonary atresia and stenosis are never associated with aneuploidies.

      The incidence of cardiac abnormalities is

      90% in trisomy 13

      40-50% in trisomy 21

      15-20% in Turner’s syndrome

      Echocardiography has been discussed in a chapter devoted to it in detail. But it is still essential to emphasize at this point that with advancing technology of ultrasound, it is now possible to study fetal heart transvaginally in late first trimester in detail.

Abdominal abnormalities

Diaphragmatic hernia

      10-20% of fetuses with diaphragmatic hernias have chromosomal anomalies, commonest being trisomy 18, but are more significant when associated with other abnormalities, especially increased nuchal translucency. Diaphragmatic hernia is diagnosed in ultrasound by assessing the transverse section of the thorax at the level of four chamber heart. Heart is displaced to right side and stomach shadow or bowel shadows are seen at the same levels as the heart. Stomach shadow is not seen in the abdomen. Though liver herniation in the thorax is rare, if present displaces the heart to further left side. In cases of diaphragmatic hernia, prognosis depends on the resultant pulmonary hypoplasia.

Duodenal atresia

      1/3^rd of the fetuses with duodenal atresia have trisomy 21⁹. But duodenal atresia is very difficult to diagnose before 20-24 weeks. Karyotyping is a must when duodenal atresia is diagnosed.

Omphalocoele

      It is physiologically present from 8^th to 12^th weeks of gestation but is considered abnormal if it persists after 12^th week of gestation. It increases the risk of Trisomy 18. Even before 12^th week an Omphalocoele may be considered abnormal:

      - if it has a neck of more than 7mm

      - if it is larger than or of the size of the abdomen or

      - there is herniation of the liver.

      An Omphalocoele may contain bowel or liver, but those containing liver are usually not associated with aneuploidies¹⁰. When it contains bowel, it appears more echogenic than abdomen, and when it contains liver, abdomen is more echogenic.

      The bowel containing Omphalocoele, which is hyperechoic to the liver, is commonly associated with syndromes. About 40-60% of the fetus have chromosomal anomalies and is 10 times more common in fetuses with increases nuchal translucency. Others are likely to have nonchromosomal syndromes like Turner’s syndrome or uniparental disomies. 50% of bowel containing omphalocoeles are associated with cardiac anomalies.

Genitourinary anomalies:

      The commonest ones associated with chromosomal abnormalities are bladder outlet obstruction and Megacystitis and are most commonly associated with Trisomy 18 and 13¹¹. More proximal genitourinary tract malformations are less associated with chromosomal abnormalities, and the risk is still lower with unilateral affections.

      Fetal kidneys are consistently seen after 11 weeks of gestation normally. Their absence may indicate agenesis which may be confirmed by absence of renal vessels also (unilateral or bilateral) on Doppler examination. Kidneys are hyperechoic oval structures at 12 weeks. Dysplastic kidneys though may appear large with cystic lesions. Renal pyelactasis has been discussed with chromosomal markers.

Skeletal abnormalities

      Limb reduction deformities and radial aplasia indicate a risk of trisomy 18.

      Isolated club foot is not commonly associated with chromosomal abnormally, especially in an otherwise low risk patient. But there is one consensus that whenever a club foot is seen, a fetal Karyotyping must be done because there is a possibility of presence of many other subtle abnormalities, which are very likely to be missed on sonography, it a very careful detailed search is not done.

      Hand makes an important landmark for chromosomal abnormalities. Clinodactyly is seen in T21, clenched hands in T18, polydactyly in T13, and syndactyly in triploidy.

      Generalised skeletal dysplasias like achondroplasia, achondrogenesis can be diagnosed on late first trimester scan by disproportionately short long bones. Osteogenesis imperfecta is diagnosed by noncalcified, non-ossified bones. This may be seen as less echogenic bones of skull and limbs.

      Sirenomyelia (fusion of lower limbs) if present can be diagnosed as early as 10-11 weeks and is commonly associated with other abdominal structural abnormalities and single large umbilical artery.

Miscellaneous abnormalities

      Ascites and hydrothorax suggest possibility of aneuploidy or infection, especially when present without hydrops.

      As such any abnormalities in the fetus should lead us towards the search for the chromosomal anomalies, except the acquired disorders which are a result of tissue or vascular disruption e.g. Tumours, hydranencephaly, amniotic hand syndrome, limb body wall complex, jejuna atresia due to vascular insufficiency and gastroschisis and complex anomalies like cardiospleenic syndrome.

Markers, as already been discussed are not structural abnormalities but are subtle variations in the normal anatomy, that point towards chromosomal abnormalities. If sonographic markers for fetal anomalies are taken into consideration with other sonographic findings, 50-70% of Trisomy 21, 80% of trisomy 18 and 90% of trisomy 13 fetuses will show positive genetic sonogram.

These markers are divided into major and soft markers depending on their sensitivity for the diagnosis of aneuploidies.

Major or most indicative markers:

Nuchal translucency-Cystic hygroma

Ductus venosus flow

Nasal bone length

Nuchal Translucency

Normally nuchal translucency is 1.5 to 2.5 cms between 10-12 weeks and 2 to 3mm between 12-14 weeks. Nuchal translucency increases by 17% every week. It must be remembered that there is no cut off value for nuchal translucency. It has definite values for definite gestational age. Though any value above 3mm surely requires counseling.

     

Measuring Nuchal translucency: (FMF guidelines):

When CRL is between 45 and 84 mms

In true sagittal section, in which following landmarks are seen.

Echogenic tip of the nose

Nasal bone

Rectangular shape of palate anteriorly

No bone is seen between nasal bone and palate

Fluid in third ventricle between thallami

Aqueduct of Sylvius in between cerebal peduncles.

Mandible is seen as a point

With maximum magnification 75% of the screen should be covered caliper showing 0.1mm minimum measurement.

Only head and upper chest is seen.

Neutral position-neither extension, nor flexion because nuchal translucency increases by 0.6mm on extension & reduces upto 0.4mm on flexion of the fetal neck. Cord round neck causes false increase in NT by 0.8mm Measurements above and below the cord may be different.

Translucency between the skin and soft tissues posterior to the cervical spine, is to be measured.

When nuchal translucency is measured in this way the interobserver and intraobserver  error is only of <0.5%

Nuchal translucency may be increased due to several causes like chromosomal defects, cardiac abnormalities, lymphatic or venous drainage abnormalities, fetal infection or anemia. 75-80% of the fetuses with trisomy 21 and 5-10% of euploids fetuses. Show increased nuchal translucency. But in euploids fetuses with increased NT prevalence of major defects was 7.3%.

Causes of increased nuchal translucency:

Chromosomal anomalies: Altered extracellular matrix composition is seen in chromosomal abnormalities as the component proteins of extracellular matrix is encoded on chromosomes 21, 18 and 13. It has also been found in other genetic syndromes like achondrogenesis type II due to altered collagen metabolism, in achondroplasia and thanatophoric dysplasia due to abnormal fibroblast growth factor receptors and in Zellweger’s syndrome due to disturbed metabolism of peroxisome biogenesis factor.

Cardiac abnormalities & overload in T T transfusion The prevalence of the cardiac defects increased from <3% at nuchal translucency of <3mm at 14 weeks, to 15% if it was >5.4mm¹².

Venous congestion due to fetal constriction in case of amniotic rupture or superior mediastinal compression, diaphragmatic hernia or narrow chest due to skeletal dysplasias.

Delayed development of lymphatic drainage

Neuromuscular defects like fetal akinesia sequence leading to impaired lymphatic drainage.

Congenital infections causing fetal anemia and cardiac dysfunction.

Anemia and hypoproteinemia

Increased nuchal translucency may resolve at and after 16 weeks. More over the subcutaneous fat deposition starts after 16 weeks and then the significance of nuchal translucency decreases. What we measure after 16 weeks is nuchal fold thickness and not nuchal translucency. It is very important to remember here that spontaneous resolution of increased nuchal translucency does not exclude chromosomal defects. A normal karyotype in the fetuses with increased nuchal translucency also does not exclude structural abnormalities.

Significance:

Nuchal translucency only picks up Down’s syndrome in 85% of high risk patients and in 75% of low risk patients.

Maternal age + NT + NB + Serum parameters have 97% sensitivity with 5% false negative rate.

The fetal medicine foundation multicentre project report show:

Assessment of risk by combination of maternal age and nuchal translucency followed by invasive diagnostic testing for 5% of pregnancies with screen positive result and selective termination of affected fetuses, would reduce the live birth incidence of trisomy 21 by 75%¹³.

The risk value of nuchal translucency can be more reliably calculated by plotting the value on the nomogram for the nuchal translucency and then using its MoM (mean of median) (value to calculate the likelihood ration of the fetus having trisomy 21. The prevalence of defects increase from 0.8 pr 1000 to 65.8% per 1000 as the NT increases from below fifth percentile to above ninetynineth percentile.

Apart from trisomy 21, increased nuchal translucency is also associated with other chromosomal abnormalities, and the diagnosis can be guided by a few associated features

Trisomy 18: early IUGR, relative bradycardia, omphalocoele (Both free bhCG and PAPP-A are low).

Trisomy 13: IUGR, relative tachycardia, omphalocoele holoprosencephaly

Turner’s syndrome: Early IUGR, tachycardia

Triploidy: Asymmetrical IUGR, bradycardia, holoprosencephaly, omphalocoele, posterior fossa cyst, molar changes in placenta.

In twin babies with twin to twin transfusion, nuchal translucency is frequently increases, in recipient fetus. It is a manifestation of heart failure due to hypervolemic congestion. As the gestation advances, there would be dieresis, which will correct the hypervolemia, decrease the heart strain and resolve the nuchal translucency.

Limitation

If normal nuchal translucency is considered as THE sign for a normal embryo, chances are there to miss 48% of abnormal babies, so detailed structural scan is always a must.

Increased nuchal translucency, as a single sign may be rarely seen in a normal baby also.

Nuchal fold thickness:

      Nuchal fold thickness is measured as the total soft tissue thickness behind the cervical spine. It is measured in axial plane on transcerebellar section. It is to be measured only between 15-20 weeks when the skin thickness is constant. It is normally <5mm, though if plotted n graphs as MoM, it has specific likelihood ratios at a particular thickness and particular gestational age. It is found to be increased in 0.1% of normal but 80% of Down’s fetuses, and is also seen in fetuses with Noonan is syndrome and cardiac abnormalities. Like nuchal translucency, this also may be a transient sign or may be present after resolution of cystic hygroma, but that does not decrease the risk of aneuploidy and must be considered as important as nuchal translucency for the suspicion of aneuploidy or cardiac defect.

Cystic Hygroma

      Is grossly increased nuchal oedema which extends beyond neck to involve the back and the head also. Cystic hygroma may or may not be septated. Nonseptated nuchal oedema increases the risk of cardiac defects or trisomies, where as septated cystic hygroma is almost invariably associated with Turner’s Syndrome.

      Cystic hygroma is the one isolated abnormality, where invasive testing is must because 47-73% of fetuses with cystic hygroma have cytogenic anomalies and 1/3^rd fetuses have nonimmune hydrops. But isolated cystic hygromas in atypical location are not notably associated with chromosomal abnormality.

      In 37% of fetuses, cystic hygroma will resolve in 2^nd trimester. If it progresses to lymphangiectasis or persists in 2^nd trimester, chances of Turner’s syndrome are more and it may be fatal.

      Milder cases of cystic hygroma have better prognosis. Surgical correction after birth is possible. But even after surgery for correction of cystic hygroma, bony abnormalities of mandible occipital bone & vertebrae and facial palsy may persist.

Ductus venosus flow

Ductus venosus is a vessel that connects the umbilical vein to the right atrium of the fetal heart. It has no anatomical continuity with the umbilical vein but connects portal sinus to the umbilical sinus. It is only 2 mm in diameter at its inlet into the umbilical sinus but carries 56% of the total fetal oxygenated blood. This vessel can be visualized in midsagittal longitudinal section or oblique transverse section through upper abdomen as a most bright spot on colour Doppler. It shows a continuous forward triphasic flow normally where the first peak indicates the ventricular systole, the downward stroke of the pitch corresponds to ventricular diastole and the second peak corresponds to the atrial systole. Reversed diastolic flow that means an absent 2^nd peak or reversal of the 2^nd peak indicates chromosomal or cardiac anomalies. Though early in first trimester an immature sphincter of ductus venosus would give a reversal of the 2^nd peak due to back flow of blood into the ductus with atrial systole. Absent / inverted ACV has been seen in about 70-90% with chromosomal anomalies¹⁴.

40% fetuses having an abnormal ductus venosus waveform show increased nuchal translucency. Evaluating it inversely, fetuses with increased nuchal translucency showed abnormal ductus flow in 90% of chromosomally abnormal fetuses or with cardiac defects.

An abnormal ductus flow in trisomy 21 can be explained by increased levels of atrial and brain natriuretic peptide mRNA in fetal heart suggesting heart strain.

But this alteration in the waveform must be very carefully evaluated as it is very common to make a mistake of examining the hepatic vein instead of ductus venosus, which would normally show flow like abnormal ductus venous flow.

Nasal Bone

      As is often observed the Down’s Syndrome babies have a flat nasal bridge and a flat nose. This observation was applied into the fetal evaluation foe diagnosis of Down’s syndrome. It was observed that 40% of Down’s syndrome fetuses have absent nasal bone, but no euploids fetuses showed this finding¹⁵. The risk of Down’s syndrome increased by 146 folds if nasal bone was absent. Likelihood ratio of absent nasal bone for Down’s syndrome is as high as 83.

      So that makes nasal bone a very important marker, independent of nuchal translucency for diagnosis of aneuploidies. That means the nasal bone measurement should have minimal interobserver and intraobserver error and should be reproducible. Therefore it has been standardized that nasal bone length should be measured when CRL is 65-74 mm, with the ultrasound beam at 45^o angle and perpendicular to the nasal bone.(FMF guidelines). The expected length of the nasal bone is 3mm, but 2mm is considered to be the cut off limit of normal. Even if the nasal bone length is 3 mm at 11 weeks, it needs to be doubled in length by 14 weeks. If it does not, aneuploidies must be suspected and an intense search for any other markers must be done. But it must be remembered that 0.5% of normal patients have absent nasal bone and it a detailed US and a triple marker test does not show any indication of trisomy 21, follow up scans should be done and any structural abnormalities must be looked for.

It must be remembered that incidence of absent nasal bone decreased with fetal CRL, increased with Nuchal translucency thickness and was substantially high in Afro-Carribeans than in Caucasians¹⁶.

      According to the recent literature, it is enough to be able to identify the nasal bone. Its length is not important.

Though the sensitivity for Down’s Syndrome of individual marker is as follows

Nuchal translucency 80.4%

Nasal Bone 58.7%

Ductus venosus flow 93.5%

All three together have a sensitivity for Down’s syndrome of 94% with likelihood ratio for negative test only 0.08%.

      Apart from these there are some new markers for aneuploidies that are gaining a lot of importance and significancy lately. These are:

Facial angle or Fronto maxillary facial angle (FMF angle)

Tricuspid regurge

Though not a marker for chromosomal abnormalities IT is also an important measurement to exclude open spinal defects that may be a part of chromosomal abnormality.

Fronto-maxillary facial angle:

      In midsagittal plane of the face a line is drawn on the superior surface of the maxilla that is rectangular in shape and a second line is drawn from the anterior point of maxilla to the nasal bridge. But it needs to be a true midsagittal plane. Rotation of even 5-15^o will lead to error of 2-3^o. In normal fetuses this angle is 66.6^o-89.5^o, mean 78.1^o but it decreases with increase in CRL: it is 84^o at CRL 45mm to 76.5^o at CRL 85mm.

Incorporating FMF angle in 1^st trimester combined screening increased the estimated DR of T21 from 90-94% at FPR 5% and from 85% to 92% at FPR of 3%¹⁷.(DR: detection rates, FPR: False positive rate)

Tricuspid regurge:

      Four chamber heart view is the section required for assessing the tricuspid valve flow. With the new advances in ultrasound technology, now this view cab be achieved on the nuchal scan. The sample gate of pulse Doppler is placed across the tricuspid valve with a sample gate of 2-3 mm and the spectrum of flow is documented. Tricuspid flow is a positive flow during ventricular diastole and is absent during ventricular systole. Reverse flow during ventricular systole that involves more than half of the systolic phase and has a velocity of 60cms/sec or more is abnormal. This is a marker for chromosomal and / or cardiac abnormality in the fetus.

      Tricuspid regurge is seen in¹⁸

Euploid          0.9%

T21                 55.7%

T18                 33.3%

T13                 30.0%

Turner’s         37.5%

Intracranial translucency (IT):

Midsagittal plane (same as the plane for nuchal translucency) is absolute essential.

This is the space between the posterior margin of the brainstem and anterior margin of choroid plexus of fourth ventricle, in the same plane as that for nuchal translucency and parallel to NT.

It is a curved translucency, widest in the middle of the fourth ventricle.

IT is normally 2-3mm, anything less than 2mm is seen in fetuses with open spinal canal defect.

Apart from these markers, there are some other markers, which though have a lower sensitivity for aneuploidies than the major markers, are seen much more often in the aneuploidies rather than normal fetuses.

These are soft markers and can be listed as follows:

Ventriculomegaly

Strawberry shaped skull

Choroid plexus cyst (cpc)

Echogenic cardiac focus

Renal pyelactasis

Megacystitis

Hyperechoic bowel

Clino/syn/polydactyly

Short long bones

Wide iliac angle

Umbilical cord abnormalities

 Extrafetal abnormalities

1. Ventriculomegaly:

      The ventricular size remains relatively constant throughout gestation at 6.1 ± 1.3mm, though is slightly larger in males and smaller in females¹⁹. As a rule anything less than 8mm is considered as normal. 8-10mm is borderline and 10-12mm is mild Ventriculomegaly. The ventricular size larger than that is called a hydrocephalus and not a Ventriculomegaly. Visually, when the choroid plexus of the dependent ventricle is seen hanging away from the medial ventricular wall (separation of >3mm), is considered as ventriculomegaly. Ventriculomegaly as a single sign is not a very significant marker and demands only a close follow up, but may be one of the markers of trisomy 18, 13, 21 and triploidy. The odds ratio of mild ventriculomegaly for chromosomal abnormality is 4.4%²⁰.

2. Strawberry shaped skull is seen in trisomy 18, but associated findings must be looked for. Its combination with CPC increases the risk of Trisomy 18.

3. Choroid plexus cyst: Choroid plexus cyst is seen in 0.3-3.6% of the population between 16-24 weeks. They are transient in 80-94% and disappear at 24 weeks in euploid or aneuploid fetuses. Choroid plexus cysts have no adverse fetal outcome if the karyotype is normal.

      Though choroid plexus cysts are seen in 1% of normal fetuses but are seen in 50% of trisomy 18 fetuses. Single choroid plexus cyst which is <3mm in size and which are transient are less likely to be associated with aneuploidies, Multiple or bilateral choroid plexus cysts and especially which persist for al longer time or disappear lat have higher risk for aneuploidies, but any associated abnormality with choroid plexus cyst increases the likelihood ratio by as much as 20 times²².

Approximate risk of Trisomy 18 in fetuses with CPC²¹

Gest. Wks	Baseline	Isolated cyst	Other abn.
20-24	1:4500	1:2950	1:225
25-29	1:3600	1:2300	1:175
30-34	1:2000	1:1300	1:100
35-39	1:750	1:470	1:35
40-44	1:400	1:100	1:10

     

A ripple marker must be done for fetuses with isolated CPC to select the ones which need amniocentesis. If Karyotyping is not done, there is no point in doing a follow up scan for CPC as they are transient. A follow up scan only helps to detect other abnormalities which may be missed.

4. Echogenic cardiac focus:

      An echogenic dense spot of 1-6mm is sometimes seen in the cardiac ventricles which moves in the heart like a golf ball with each ventricular contraction, as it is attached to the paplillary muscle or chordate tendinae. A single such focus may be seen in the left ventricle in 3-10% of the population and is commoner in fetuses of Asian mothers than in fetuses with Down’s syndrome. The sensitivity and the specificity of this marker is low. It has a likelihood ration for Down’s syndrome of 1.8-4.2%²³. But when such foci are multiple or are in the fight ventricle or bilateral, the risk increase to double. Less than 20% of aneuploid fetuses have echogenic cardiac focus. It is seen in 16% of fetuses with T21, 39% of fetuses with T13 and in 2% of normal fetuses²⁴.

5. Renal pyelactasis:

      Renal pelvis diameter is 3-4 mm a 14-15 weeks in AP diameter when fetal abdomen is seen in transverse section. It must be a true transverse section when renal pelves are seen but stomach or bladder is not seen. The measurement is taken from inner margin to inner margin of renal pelvis. When this diameter increases to >4mm it is called pyelactasis and it increases the risk for trisomy 21 by 1.6 folds²⁵. Though 2-3% of normal fetuses have pyelactasis, it is seen in 17-25% of Down’s syndrome fetuses. Though often a transient sign, renal pelvic diameter of

4mm between 16-20 weeks

5mm between 20 30 weeks

7mm between 30 40 weeks is considered abnormal.

6. Megacystitis:

      Normally in all fetuses beyond 67mm of CRL, the bladder id visible. Normal emptying time cycle is 30-155 minutes. Megacystitis id defined when the bladder vertically measures >8mm or bladder diameter/CRL >13%. 20% of the fetuses with that does not exclude the risk of aneuploidy. Risk is significant when it is due to obstructive uropathy and associated with other abnormalities.

7. Hyperechoic bowel:

      The bowel is normally also a mildy hyperechoic to the liver due to multiple tissue interfaces, but when it is more dense than normal is known as hyperechoic bowel. It is a normal variant in 2^nd trimester and is detected in 10% of trisomy 21 fetuses between 14 and 24 weeks. According to the density and the uniformity it can be graded as²⁶

      - Grade I: homogenously mildly hyperechoic

      - Grade II: focal hyperechogenecities

      - Grade III: as echogenic as bone

            Hyperechoic bowel may be seen in fetuses with

      - Aneuploidies

      - Meconium ileus due to cystic fibrosis

      - Bowel atresia

      - Congenital infections like CMV (cytomegalo virus).

      The fetuses with grade 2 and 3 echogencecity of bowel, have a higher risk of aneuploidies. Hyperechoic bowel increases the risk for trisomy 21 by 6-7 folds²⁷. It is found in 12% of fetuses with T21. Even when the fetus is an euploid, it has a risk of IUGR or IUD.

8. Phalangeal abnormalities

Clinodactyly: trisomy 21 (Ratio of middle phalanx of fifth digit to middle phalanx of fourth digit in Down’s is 0.59 (median), normal 0.85)

Polydactyly: trisomy 13

Syndactyly: triploidy

9. Short long bones:

      When femoral length show a difference of 2 weeks or more than the other biometric parameters, it has a significant risk of aneuploidy, especially trisomy 21 and 18. But short humerus is considered to be more sensitive for Trisomy 21 than short femur.

10. Wide iliac angle:

      Normal iliac angle is upto 90^o, but when >105^o is a strong indicator towards trisomy 21, 18 and 13. The iliac angle shows a variation of 15.6, from above downwards, and also when spine is on one of the sides. Though 3D US can give better and more reliable result.

11. Umbilical cord abnormalities

      Umbilical cord diameter, though is not normally measured routinely, does have its own nomographic values. When it is above 95^th percentile, it is considered as abnormal and may increase the risk of eneuploidy²⁸.

      Single umbilical artery was though once considered as a very significant marker, is seen in normal fetuses also. Single umbilical artery should definitely lead to a detailed search for chromosomal or cardiac abnormalities, but has a significant value only when associated with other abnormalities.

      Reversed end diastolic flow in umbilical artery at 10-14 weeks is associated with chromosomal anomalies.

12. Extrafetal markers

      Unfused amnion beyond 14 weeks suggest a risk of trisomy 21. Placental thickening or cystic areas are associated with aneuploidies. Cystic areas in the placenta suggest a possibility of trisomy 18 and 13, especially when associated with oligohydramnios or IUGR.

      The risk for aneuploidies increases when

Multiple markers are present

Markers are seen at the higher age of gestation

Fetus shows delayed development.

The risk of aneuploidy increases by 9.04 odds ratio if the CRL was 14mm or more decreased than the expected. Early onset IUGR is usually associated with Trisomy 18 or 13. 96% of the fetuses with IUGR have multisystem abnormalities, characteristic of type of aneuploidy. Though usually symmetric IUGR, triploidy shows asymmetric IUGR. IUGR with polyhydramnios / oligohydramnios has higher risk.

Gestational sac large for dates

Cardiac anomaly or duodenal atresia is present

But when we say that the risk is increased, does not suffice. It is important to exactly calculate the risk in order to allow the patient take a balanced decision regarding the continuation or termination of pregnancy.

Background Risk Factors

Background risk: maternal age + gestational age + previous pregnancy with aneuploidy.

Maternal age>35

Paternal age>39, three times increased risk

Previous chromosomal anomaly : previous aneuploid child has an additional risk of 0.75% translucency to the risk otherwise calculated as background risk.

Biochemical careening positive.

Increasing gestational age: 30% of trisomy 21 fetuses die between 12 weeks of gestation and full term and 20% between 16 weeks and full term. That means that with increasing age of gestation the number of aneuploid fetuses decrease, due to nature’s law of existence of the strongest’. So if the markers for chromosomal abnormality are detected at the higher gestational age means that the likelihood of this fetus being abnormal increases.

Likelihood ratio=Cases%/Controls%.

     Likelihood ratio (LR) is calculated for a particular finding by dividing the percentage of abnormal fetuses / percentage normal fetuses with that particular finding / measurement

Chart of risk increase with each abnormal marker:

Marker	Isolated	Incombinations
Increased NT	15	60-95
Short humerus	05	15-23
Short femur	04	06-10
Echogenic cardiac focus	04	06-08
Hyperechoic bowel	03	15-33
Choroid plexus cyst	1.5	Same
Mild hydronephrosis	1.5	05-09
Normal scan	0.2	---------

      Moreover, more the markers, more is the risk. A single marker increases the risk twofold, two markers increase the risk nearly tenfold and three or more markers increase the risk to more than 100 folds. Though the actual risk depends on the type and number of markers that are present.

No of markers	Likelihood ration
1	0.2
2	1.9
3	6.2
4	80

      A normal US has a likelihood ration for aneuploidy of only 0.2-0.4 and decreases the risk by 60-80%²⁹.

45% of risk of chromosomal anomalies is decreased if US is normal, though the biochemical markers are positive. Neyberg.

      The scanner’s aim should be to minimize the false positive results in low risk group and maximize the sensitivity in the high risk group. With this aim a scoring index system has been devised by Benacerraf et al. She decided a score of 2 for structural abnormalities and nuchal thickening and 1 point for other markers. All those having a score of more than 2 was offered amniocentesis. Some prefer to modify this system by adding 1 point for maternal age of 35 or more and 2 points for the age of 40 and more.

      Another method of risk assessment based on US is AAURA- age adjusted ultrasound risk assessment. Here a priori risk of the maternal age is multiplied by the likelihood ratios of the individual sonographic marker. This in low risk group gives a sensitivity of 61.5% with a false positive rate of only 4%.

      Though being so significantly helpful for the diagnosis of aneuploidies, sonography is not useful for diagnosis of single gene disorders like thallasemia or muscular dystrophy, which show no structural variations or abnormalities.

            A detailed, well performed anomaly scan can reduce the rate of invasive testing and number of abnormal births. Kypros Nicholaides.

Biochemical correlation:

      Ultrasound findings are independent of maternal age and biochemical markers and so a combined risk assessment using both ultrasound and biochemistry could be more erective and less confusing than competing results from each. The new biochemical risk assessment systems now incorporate humerus length and nuchal thickness measurements to increase the sensitivity, in 2^nd trimester.

      Increased bHCG, which normally falls after 10 weeks, and low PAPPA are markers of down’s syndnrome³⁰.

      Sex chromosomal abnormalities: normal bHCG, low PAPP-A

      Triploidy: mildly low PAPP-A, Very high bHCG.

      Inhibin assessment can be also added to the standard second trimester biochemical testing.

But remember:

      Detection of even minor markers in second trimester ultrasonography increases the risk of an abnormal karyotype. The sensitivity, though is much lower than that of nuchal translucency in first trimester.

      The actual sensitivity of a genetic sonogram depends on various factors, including the markers sought, gestational age, reasons for referral, and quality of ultrasound. The increasing detection rate of cardiac abnormalities have increased the detection rate of aneuploidies by sonography from 60% to 90%.

Systematic examination of fetal Central nervous system

Introduction:

      Abnormalities of central nervous system are the commonest of all congenital anomalies. Neural tube defects are most frequent of these and the incidence is 1-2 per 1000 births. Though intracranial anomalies with intact neural tube are often missed antenatally and so exact incidence of central nervous system abnormalities is not known but is estimated to be approximately 1 in 10.

      US has been used for nearly 30 years now for diagnosis of fetal CNS abnormalities. With increasing efficacy of technology, the anatomy of CNS can now be studied much more in detail than ever before and as early as late first trimester.

      To study and diagnose CNS abnormalities precisely it is important to know the development of the brain, as brain has the most dynamic anatomy amongst all the body organs during embryonic life. The developmental maturation of the normal brain follows a predictable timetable and this maturation can be followed by ultrasonography¹.

      Though is selected cases fetal MRI after 20-22 weeks has given promising results, its advantage over ultrasound remains debated².

      To make the examination standardized, of this quick changing anatomy, ISUOG (International Society of Ultrasound in Obstetrics and Gynecology) has established guidelines of CNS examination. The examination has been staged as:

I.   Optimized approach to the evaluation of fetal CNS: Basic examination

II. Detailed evaluation of fetal CNS: fetal neurosonogram: indicated for pregnancies at high risk for CNS abnormalities and may need 3D US.

Time of examination:

      For basic studies in low risk population, around midgestation- 20 weeks is a good time for the study of fetal CNS. Studies later in gestation hampers visualization of intracranial structures because of culvarial ossification. First or early second trimester scans at 14-16 weeks has an advantage that bones are thin and brain evaluation from all angles is possible. Though with high end machines it is now possible o assess the fetal neural development from as early as 8-9 weeks.

Equipment & approach:

Transabdominal approach: Transducer frequency is 3-5 MHz. This is the most commonly use approach usually for basic examination and is adequate for any fetal presentation. The sections most easily obtained by this approach are axial and sometimes coronal. Sagittal sections are very difficult by this approach. The quality of image is deteriorated by factors like maternal obesity, adverse fetal position inadequate liquor and advanced pregnancy leading to calcification of fetal culvarium.

Transvaginal approach:

5 and 10 MHz transvaginal probe is used. This being a high frequency probe gives much more details and is a more preferred approach for detailed fetal neurosonogram. Whenever fetus is in cephalic presentation and fetal head is not too high, this route of examination is chosen. Gentle manipulation of the fetus may be required for correct sections and planes.

Method of transvaginal scan:

      This scan is done through anterior fontanelle of the fetus. All sections are fanning from front to back or side to side respectively parallel to coronal and sagittal sutures. Transverse or axial sections can not be obtained by this approach.

      The coronal sections obtained are divided as frontal 1, 2, midcoronal 1, 2, 3 and occipital 1, 2 and the side to side sections obtained are median & paramedian 1, 2. These sections are similar to the neonatal scans and so easier to understand for pediatricians. 3D may be used with both the approaches whenever indicated.

Technical specifications:

Gray scale

Harmonics: enhances subtle anatomical details

Colour and power Doppler for vascular studies: to pick velocities of 20-40 cms.sec

Increased persistence to pick up small vessels

The basic fetal CNS evaluation is divided into

Qualitative evaluation

Quantitative evaluation

a. Qualitative evaluation of head consists of three axial planes

Transventricular plane

Transthallamic plane

Transcerebellar plane

 b. Qualitative evaluation of the spine requires at least two of the three planes

Longitudinal/ sagittal

Transverse/ axial

Coronal

Qualitative examination of the head

Transventricular plane

Head shape

Lateral ventricles

Cavum septum pellucidum

Thallami

Cerebellum

Cisterna magna

Lateral Ventricles:

      Lateral ventricle consists of anterior horn (frontal horn), posterior horn (Occipital horn), atrium contains glomus of choroid plexus and inferior (temporal horn). In first trimester, the ventricle are large and fill up almost the whole cranial cavity with choroids plexus in the centre. As the fetus grows the comparative size of the ventricles decreases and the inferior horn is almost obliterated by 18 weeks. In second trimester the lateral ventricles are seen only as anterior and posterior horns and atrium, which is occupied by choroid plexus. In transventricular section the maximum normal ventricular diameter is 7.6 ± 0.6 and remains fairly constant in 2^nd and 3^rd trimester. Medial and lateral walls of ventricle are parallel to midline in 2^nd and 3^rd trimester³.

      The lateral ventricle to hemisphere ratio decreases from 70% at 18-20 weeks to 30% at 28-29 weeks and remain steady there after. The ration of anterior horn width to the hemisphere decreases from 60% at 14 weeks to 40% at 21^st week⁴.

      The ventricular width is measured from inner to inner margin at the atrial level. Anything more than 10mm is termed as ventriculomegaly and ventricular size of more than 15mm with increased intracranial pressure is hydrocephalus. Dilatation of only posterior horn (tear shaped ventricles) which is seen in agenesis of corpus callosum, is known as colpocephaly.

      Choroid plexus normally fills the atrium. Thinned out and hanging/ dangling choroid plexus is an indirect sign of ventricular dilatation. An angle can also be measured between a line along the median margin of the ventricle and posteromedial margin of the choroids plexus.

      Most severe cerebral lesions are symmetrical and in basic examination symmetry of the brain is assumed, as most of the times the hemisphere on the near side is not visualized.

Cavum Septum Pellucidum: (CSP)

      Sonographically it appears as 2 sheets of tissue which extends from corpus callosum and separates the lateral ventricles from Cavum. It becomes visible at 16 weeks and remains nearly steady through out the 2^nd trimester but obliterates near term. It must always be visualized between 18 and 37 weeks when BPD is between 44-88mm. Septum Cavum pellucidum is not seen in

holoprosencephaly.

agenesis of CC.

severe hydrocephaly

septooptic dysplasia.

Pathologies diagnosed on this plane:

      2. Transcerebellar plane:

            It cuts through cerebellum and shows

Frontal horns of lateral ventricles

Cavum septum pellucidum

Thallami

Cerebellum:

Two hemispheres

Vermis after 20 weeks

Cerebellum which is seen as a B shaped structure in the posterior fossa in 2^nd trimester and onward pregnancy becomes visible as early as 11-12 weeks. In 2^nd trimester, its diameter in mms corresponds to the number of weeks of gestation. In late 2^nd and third trimester sulci and gyri can also be appreciated on cerebellar surface. Between the two cerebellar hemispheres a thin solid structure is seen called vermis. Inferior vermis is seen at a little caudal level than superior vermis. It is consistently visible after 18 weeks, but is sometimes absent in Dandywalker’s syndrome and variants and also present as a solitary finding. When inferior vermis is absent the cisterna magna communicates with 4^th ventricle and is seen as an open ‘V’ between cerebellar hemispheres.

Cisterna magna:

      This is the space between the cerebellum and the occipital bone and shows thin arachnoid septations as lines crossing the lucent space anteroposteriorly. Cisterna magna is enlarged in Dandywalker’s syndrome, Dandywalker’s variant of mega cisterna magna.

3. Transthallamic plane:

      The plane is commonly known as biparietal plane and is easily reproducible in late pregnancy. It shows

Frontal horns of lateral ventricles

CSP

Thallami

Hippocampal gyrus

Lateral sulcus (absence indicates lissencephaly)

Study of the cerebral vasculature:

      Cerebral circulation is first detectable at 8 weeks and can be seen in all the fetuses at 11 weeks. The circle of Willis which is formed by two posterior cerebral arteries, a posterior communicating artery, two middle cerebral arteries, two anterior communicating artery, is the landmark of fetal circulation.

      This circle can be examined on axial plane and MCA is the most commonly interrogated vessel in fetal circulation. From Transthallamic view, slight angulation of the probe towards skull base gives a good view of circle of Willis. From circle of Willis, vessel traveling towards the probe in Sylvian fissure is middle cerebral artery. It has a high resistance flow in first trimester but with increasing gestational age the resistance decreases and peak systolic velocity in this vessel increases. MCA PI remains constant till 32 weeks and then falls.

      Low resistance (<5^th cenrile) flow in this vessel especially in third trimester is an indication of compensating fetal hypoxia. But an absent diastolic flow in this vessel in third trimester is often and indication of noncompensating fetal hypoxia and cerebral oedema, though it needs to be correlated clinically as well as with other ultrasonographic signs of fetal hypoxia. Increase in peak systolic velocity beyond 2SD indicates fetal anemia.

Qualitative evaluation of Fetal Spine

      Full examination of spine with all projections is not a part of basic examination. This requires expertise and extra skill.

      Longitudinal section is must. After 14 weeks always three ossification centres are seen as three parallel lines. It is important to see intact overlying skin on long and transverse section.

Quantitative Assessment of head:

      Measurements include:

Biparietal diameter

Head circumference

Internal diameter of the ventricular atrium

Cerebellar transverse diameter

Depth of cisterna magna

Biparietal diameter

      It has been a trend for many years to measure the biparietal diameter in Transthallamic plane and to measure it from outer to inner margin of the skull. The Fetal medicine foundation though prefers to measure it in transventricular plane and measure it from outer to outer wall. As far as assessment of growth is the mater, it is essential that the same method and the same section are always used for this measurement.

Head circumference

      Is measured from outside the skull bone echoes or may be calculated as HC=1.62 X (BPD+OFD). Shape of the skull is represented by the ratio BPD/OFD & 75-85% is normal.

      Moulding of fetal head in early gestation is frequent. Breech presentations may show mild dolichocephaly where this ratio is decreased and in brachycephaly this ratio is increased.

Ventricular atrium:

      It is measured at the level of glomus of choroids plexus, perpendicular to the ventricular cavity. Calipers are placed inside the ventricular walls.

      In second and third trimester it measures 6-8 mm, 8 to 10mm is borderline ventriculomegaly and >10mm is ventriculomegaly. Ventricular diameter of upto 10mm is treated expectantly, if it is a solitary finding, though it is considered as a soft marker for chromosomal abnormality. It is a marker of abnormal cerebral development. Ventricular diameter of >15mm with increased intracranial pressure is called hydrocephalus and may be associated with thinning of skull vault and widening of sutures. This may require in utero or immediate postnatal treatment.

Cerebellum

      It is measured from outer to outer margin of cerebellum. Transverse cerebellar diameter increases by 1mm every week from 14 to 21 weeks. Diameter in mms corresponds to the weeks of gestation in second trimester and is not affected by IUGR.

Cisterna Magna

      It is measured from posterior margin of cerebellar vermis to the anterior margin of overlying occipital bone. It measures 2-10mm but is slightly more in dolichocephaly. It is enlarged in cerebellar pathologies, especially in vermian ones, like Dandy walker’s malformations or variants but in neural canal defects when cerebellum is pulled caudally, it is obliterated. This is known as ‘banana sign’ of cerebellum. This is also associated with collapsed frontal bones and makes the skull shape like a lemon and is called lemon sign.

      For patients with increased risk of CNS abnormalities and suspicious findings on basic examination, a detailed fetal neuroscan is required which includes the use of multiplanar and 3D ultrasound. It has a much greater diagnostic potential. Orthogonal planes axial, sagittal and coronal are obtained by aligning the transducer with sutures and fontanelles of fetal head.

      Axial, coronal and sagittal sections of the spine are also studied as a part of detailed fetal neuroscan.

      Systematic evaluation of the head consists of detailed study of anatomical structures by

Four coronal planes

Three sagittal planes

Three axial planes

Coronal planes

Transfrontal plane (frontal 2 plane)

Transcaudate plane (midcoronal 1 plane)

Transthallamic plane (midcoronal 2 plane)

Transcerebellar plane (Occipital 1 plane)

1. Transfrontal plane:

      This plane cuts through anterior fontanelle & is rostral to the genu of corpus callosum. It shows midline hemispheric fissure, anterior horns of lateral ventricles, sphenoidal bone and orbital plates.

      2. Transcaudate plane:

            This section is at the level of caudate nuclei and cuts genu of corpus callosum. It shows corpus callosum in cut section, triangular Cavum septum pellucidum, frontal horns of lateral ventricle and sylvian fissures laterally.

      3. Transthallamic plane:

            This section cuts across the thalami which are seen closely apposed to each other on the sides of midline. Third ventricle is seen in midline. Third ventricle, more than 5mm, is considered as dilated. This section also shows interventricular foramina and atria of lateral ventricles with choroid plexus, basal cistern containing vessels of circle of Wills and optic chiasma close to the skull base.

      4. Transcerebellar plane:

            This section is taken across the cerebellum, through posterior fontanelle. It shows occipital horns of lateral ventricle, interhemispheric fissure, cerebellar hemispheres and vermis.

            For vascular studies, amongst all coronal planes the midcoronal plane is most revealing. This shows middle cerebral artery, ventriculostriate arteries, cross section of pericallosal arteries and superior sagittal sinus.

Sagittal planes

Mid sagittal

Right parasagittal

Left parasagittal

Midsagittal plane:

This section is in midline along the sagittal suture and shows corpus callosum, and Cavum septum pellucidum under it. Posterior part of the section shows brainstem, pons, vermis and 4^th ventricle, possibly aqueduct also. Fourth ventricle is seen in median plane as a sonolucent triangle at the level of cerebellum.

      Corpus callosum starts forming at 12 weeks and is completed at 20-22 weeks. It can be seen only on sagittaly section. Indirect sign of its presence is pericallosal artery. Indirect sign of absent corpus callosum is tear shaped ventriculomegaly / colpocephaly on axial section and directly upward pointing frontal horns on coronal section. But sagittal section shows absent corpus callosum with cortical sulci and gyri arising from single point instead of from corpus callosum.

      Cingulated gyrus and sulcus, the parieto-occipital fissure and calcarine fissure can be seen in this sections. Both lateral and cingulated gyri appear between 22-24 weeks. Though this is pretty late than its anatomical appearance which is at 18 weeks. Maximum sulci and gyri appear 28-30 weeks.

      Doppler studies in mid sagittal section explains the branches of internal carotid artery. Its main branches are anterior and middle cerebral arteries and pericallosal artery. Superior sagittal sinus and vein of Galen can also be seen on this section.

2) Parasagittal or oblique plane shows entire lateral ventricle with choroid plexus, paraventricular tissue and cortex. This plane is for diagnosis of intraventricular pathologies.

      Parasagittal planes can show the protective layers f the brain like scalp, skull periosteum, duramatter, arachnoid and pia matter. Scalp is seen as outermost echogenic layer. Skull is the most echogenic covering, being a bone. A thin line can be seen just under the bone that is the periosteum. Under the periosteum a distict echogenic layer is seen: the arachnoid membrane. Space between the later two is clear. This is a potential space and is more clearly seen only in presence of fluid collection. But under the arachnoid matter and above the echogenic covering of the brain, the pia matter the space is seen traversed by several linear echogenecities (blood vessels), as seen on high resolution US. These planes are also use to study the subdural and subarachnoid pathologies like heamorrhage.

Fetal Spine examination in high risk patients demands study of all the three planes.

Transverse / axial plane

Sagittal/ longitudinal plane

Coronal plane

Usually only two of these three planes can be examined in any fetus depending on its position but 3D US may be used if required.

Transverse or axial plane of spine is obtained by sweeping the probe through the entire fetal length. When this is done the level of fetal spine must be kept in mind as vertebrae have different anatomy at different levels. Upper cervical vertebrae are quadrangular, thoracic and lumbar vertebrae are triangular and sacral vertebrae are flat.

On sagittal plane:

      The ossification centers of vertebral bodies and posterior arches form two parallel lines which converge at the sacrum. Spine, if anterior, one can also see spinal canal and spinal cord, through the unossified spinous processes.

      Conus medullaris at 1.2-3 can be seen in 2^nd and 3^rd trimester. It is essential to establish the integrity of the overlying skin also. Break or discontinuity in the skin overlying the spine can sometimes be the only clue to spinal canal defect.

Coronal plane:

      This plane will show one, two or three parallel lines, depending on the section at the level of vertebral bodies or transverse process or spinous process. Regular disposition of ossification centers indicate integrity of the spine. Widening of the distance between these ossification centers indicate open spinal canal defect.

Spinal abnormalities commonly seen are

            Hemivertebrae

            Open spinal canal

            Spine bifida

            Platyspondyly

      Diastometomyelia

      Open spina bifida is often associated with cranial abnormalities. With advanced technologies now it is possible to make early diagnosis of cranial lesions.

      At 13 weeks, there is decrease in lateral ventricles dominance & choroid plexus, diencephalon and posterior fossa structures appear.

      Fetuses develop particular pattern of movement at particular gestational age and studying that would allow to assess the neurological development of the fetus.

      It is the advancement in technology, 3D and 4D ultrasound which has made the detailed fetal neuroscan very easy, less time consuming and a reproducible examination. Multiplanar mode, volume contrast imaging (VCI) and tomographic ultrasound imaging (TUI) are the ones which have made it possible to study all the transverse, sagittal and coronal planes of the head and spine from a single volume sweep.

      Fetal neurosonography is an extremely informative imaging modality that is relatively inexpensive and definitely noninvasive. Better understanding of development and neuroanatomy makes detection of pathologies easier especially by use of coronal and sagittal planes.

      Though the facts to be remembered are that

Anomalies of neuronal proliferation like microcephaly, tumours and cortical malformations may remain undetected as brain continues to develop in the second half of gestation and in neonatal period.

Moreover some cerebral lesions may also develop due to acquired prenatal and prenatal insults and in these cases antenatal development has been normal.

But the inference is that at midgestation if:

Normal transventricular and transcerebellar plane anatomy

Normal BPD and HC

Ventricular atria<10mm

Cisterna Magna 2-10mm

In a low risk pregnancy, no further examination is indicated. And even in expert hands some types of anomalies may be difficult or impossible to diagnose in utero, as they might have developed later during pregnancy or even in early neonatal life.

Role of ultrasound in diagnosis and management of IUGR

Definition:

      IUGR—intrauterine growth restriction, is suggested if gestational weeks determined by USG repeatedly show delay in the third trimester form the weeks determined by CRL or correct LMP.

      So, very simply speaking, it is a process, which limits the intrinsic fetal growth potential in utero. Though it must not be forgotten that the normal fetal growth Is influenced by genetic predisposition, parental influence, ethnic differences¹, environment (altitude) and fetal gender also. The biochemical changes associated with IUGR fetuses are lower mean glucose and cholesterol ester concentrations², higher nitrous oxide and total nitrite levels in fetal plasma and higher serum levels of inhibin and hCG.

      It is different from low birth weight (LBW) babies, which are <2500 gms at birth, despite of their gestational age or small for gestational age babies, which are smaller for their gestational age (SGA) but not necessarily growth restricted. The incidence of IUGR varies from 1% to 12%.

      It is essential to diagnose IUGR because, these fetuses have lots of immediate and late consequences like higher perinatal morbidity and mortality, perinatal asphyxia, hypothermia, persistent  fetal circulation, hypoglycemia, polycythemia and some neurological deficits and learning and behavioural problems³.

      To decide whether the fetus is IUGR or not, it is essential to first establish the correct gestational age and to assess the fetal growth by biometric measurements. The gestational age can be established by either LMP, which has a higher error rate or by first trimester or possibly earliest US-CRL measurement, which has lowest deviations from standard measurements. So earlier the fetus/ embryo is measured, more accurate is its age assessment. Even if the dating is done in the second trimester it is reliable, because acceleration of normal fetal growth does not begin till the third trimester. If the fetus is assessed for the first time in the third trimester, the transcerebellar diameter⁴ and the clavicular length⁵ can be taken to exactly assess the gestational age, because these are the ones which show the gestational age most accurately and are not affected by IUGR.

Commonest Causes of IUGR:

Maternal

Pregnancy induced hypertension

Chronic hypertension

Server Diabetes mellitus

Collagen vascular disease

Cardiac or renal disease

Smoking and poor nutrition

Previous history of IUGR baby.

Uterine placental

Uteroplacental dysfunction

Placental infarct

Chronic abruption

Multiple gestation twin to twin transfusion

Confined placental mosaicism

Fetal

Chromosomal abnormalities

Confined placental mosaicism

Major structural anomalies

Skeletal dysplasias

Multiple anomaly syndromes

Infections

Teratogens

Of all these if the aneuploidies are excluded, the commonest causes of IUGR are pregnancy induced hypertension and Uteroplacental vascular dysfunction.

Integrated classification:

            By Kurjak 1976

Type I: Intrinsic / Harmonious / proportionate / symmetrical / early

Type II: Extrinsic/Disharmonious/disproportionate/asymmetrical/late

Type III: Mixed/Semiharmonious

Type I: Harmonious

      In harmonious or symmetric IUGR, adverse factors affect since conception or embryonic stage (hyperplastic stage). The fetal weight, length and HC are uniformly affected. The fetuses are hypoplastic but eutrophic and may be called microsomies. The chances of aneuploidy in this group is 25%⁶, most commonly trisomy 18 and 13 (Dicke and Crane) and chances of malformations are very high. 20-30% are of this type.

Type II: Disharmonious

      This is most commonly seen with Uteroplacental insufficiency and affects late stage of pregnancy (hypertrophic stage). It has little or no effect on HC and FL. It typically presents as large head and undernourished body. 70-80% of IUGR are of this type⁷.

Type III: Semiharmonious

      This is also due to extrinsic factors but they affect the growth early. It is more commonly due to nutritional deficiency. The fetus is hypotrophic/ undernourished in appearance.

      When first introduced, the symmetrical IUGR was suggested to reflect an underlying fetal cause like aneuploidies, where as asymmetrical IUGR was supposedly thought to be due to Uteroplacental dysfunction. But this proved to be wrong. Triploidy fetuses show asymmetric IUGR and both symmetric and asymmetric IUGR babies show similar degree of acid-base impairment.

      We will chiefly discuss here type II IUGR only.

Risk factors for IUGR

      More than 50% of pregnancies are free of any associated conditions that would alert to the possibility of IUGR. Though the high risk mothers are with

Previous History of LBW/IUGR

Hypertension

Autoimmune diseases

Smokers

Diagnosis of IUGR

Fundal height below 5^th percentile, chronic distress id likely.

Biometric findings

Depend on the scan in the first trimester & crown rump length

if examined only in 2^nd trimester, depend of lease variable parameters. e.g. cerebellar diameter.

But the gestation age estimation and diagnosis of IUGR is also dependable by:

      Biparietal diameter

      Head circumference and cerebral index

      Abdominal diameter and circumference

      Femur length

      Fetal organ biometry

Doppler findings: most reliable method to predict and diagnose IUGR that is chiefly induced by Uteroplacental insufficiency is to depend on the first scan at 22-24 weeks.

USG diagnosis of IUGR

1. Total uterine volume

      Mostly it is believed that patients whose fundal height falls below the 5^th percentile are likely to have IUGR babies.

      LengthXwidthXheightX0.523=Volume

      IUGR when total uterine volume is <-1.5SD of mean, equivocal between -1.5 to +1.5. Errors are bound to occur due to oligohydramnios or polyhydramnios. It has a sensitivity of 60% and positive predictive value 30% for IUGR. This method is no more used.

2. Biometric Parameters

Crown rump length

Biparietal diameter

Head circumference and cerebral index

Femur length

Abdominal diameter and circumference

Fetal organ biometry

1. Crown rump length is measured before the bending of  embryo starts. (10-12 weeks).Difference of >7mm,from dates or suspicion of chromosomal anomalies.

      It is mainly used to determine the gestational age, rather than for assessment of fetal growth.

2. Biparietal diameter:

      The biparietal diameter is measured at the plane which is defined by the frontal horns of the ventricles and Cavum septum anteriorly, thalami and third ventricle in the center and occipital horns of the lateral ventricles, sylvian fissure, cisterna magna and insula posteriorly. Select the broadest part of the skull at this section and then set up the gains so that the parietal bone looks no thicker than 3mm. The measurement is taken from the outer table of the proximal parietal bone to the inner table of the distal parietal bone.

      Though depending on the shape of the skull, BPD may be variable, but it is not much affected by placental insufficiency.

      Normal growth rate of BPD:

3mm/wk till 30 weeks

1.5mm/wk 30-38wks

1mm/wk after 38wks

Nil at 42wks

      When BPD is lower than 5^th percentile, IUGR confirmed in 68% of cases, but maximum errors are likely to occur when the values are between 5^th and 10^th percentile. IUGR is suspected if growth rate is decreased (<5%) or the biparietal diameter is<10^th percentile. The accuracy of BPD is 45% at 34-36wks, provided CI (BPD/OFD) is between 70-85%, meaning that the shape of the head is normal. In general, if the curve of cephalometric parameters remains parallel to the normal curve of nomogram, it is most likely due wrong dates, but if it deviates from that and falls low, it is IUGR.

      3. Head circumference is therefore a more reliable parameter than BPD. It can be either measured directly at this same level as BPD or can be calculated as (BPD+OFD) X 1.57. Its sensitivity for IUGR is 52% and has a specificity of 80%.

Cephalometric parameters show following changes according to the type of IUGR:

Type I- below 2SD in early pregnancy and remains parallel

Type II- falls below line after 30 weeks

Type III- Intermediate pattern

Femur length and humerus length

      Long bones like femur and humerus are “bony” measurements and tend to be accurate to assess the gestational age. Femur has a typical ‘golf club’ like appearance and a moderate curvature starts developing from 18 weeks onwards. Femoral length is measured from origin of the distal end of the shaft, from greater trochanter to the lateral condyle, excluding the femoral head and the distal epiphysis in the measurement. Similarly while measuring the humerus length also, the head and the distal epiphysis are not included in the measurement. All long bones are measured on an image in which the bone is seen obliquely to the ultrasound beam.

      Femur grows at the rate of 3mm/ week from 14-27 weeks and then 1mm/ week in the third trimester. It is not / little affected in asymmetrical IUGR, but is affected in symmetrical IUGR. The ratio of FL/AC is important to differentiate the symmetrical IUGR from asymmetrical IUGR. The sensitivity of femur length is 63% for IUGR with a positive predictive value of 30%. (independent of gestational age). Humerus length is considered to be more reliable than the femur length for diagnosis of IUGR.

      Though neither BPD, nor long bone lengths have been found to be useful in diagnosing early IUGR.

Abdominal diameter and circumference:

      This represents nutrition of the fetus and reflects liver development and fetal fat deposition. It may also be affected by the level of diaphragm, depending on the extent of lung development.

      It is measured at the level of entry of umbilical vein to DV or more conveniently at the level of stomach and bifurcation of the main portal vein into right and left branches in axial plane. Care must be taken to take a section which is most rounded, perpendicular to the spine, with the ribs symmetrically covering the abdominal circumference. It is best measured during fetal apnoea and the smallest circumference is selected.

      It has a liner rise till 36 wks and fall thereafter. AC is the single most sensitive measure of fetal growth and is affected much earlier than the head or femur measurements. In both low risk and high risk subjects, AC below tenth percentile has the highest sensitivity and fetal weight has the highest odds ratio for IUGR. It has 83% sensitivity and 87% specificity for diagnosis of IUGR an allows phenotyping if IUGR is to be determined.

      Nutritional status can also be known by thigh circumference, but is not commonly used.

HC/AC

      HC/AC is the most reliable between 32-36 weeks for diagnosis and classification of IUGR. The normal values are:

      HC/AC

>1.2 at 14-16 wks

>1 till 36 wks

=1 at 36 wks

<1 after 36 wks

      At 32 weeks, it has a sensitivity 86% for IUGR and at 35-36 weeks it has a sensitivity 83% and a specificity 79%.

      Type II has, HC/AC always>1

      Type III, HC/AC >1 in 41.7% and <1 in 52.94%, and 1 in 5.82%

      Another ratio of importance is FL/AC which has a sensitivity of 63% and is independent of gestational age⁸.

Fetal organs biometry:

      This includes liver size, heart, lungs, pancreas, spleen, intestine and suprarenal study. But has very little value in diagnosis of IUGR.

      Though it must be remembered that growth arrest in a high risk fetus is an important sign of fetal distress and naturally, a dynamic evaluation of the fetal growth is more reliable and relevant than the actual biometry when the fetal measurements are below 10^th percentile. But in low risk fetuses, examinations at longer intervals better reflect the fetal growth. Ultrasound screening of an abnormal fetal growth is based on 3 basic ultrasound examinations, 8-12 weeks, 18-22 weeks and 34-36 weeks.

      There are other measures also which can be used to diagnose a compromising fetus. These include the amniotic fluid levels, biophysical profile, cardiotocography and the Doppler studies.

      Assessment of the amniotic fluid index in very essential when evaluating an IUGR pregnancy. An early onset IUGR with polyhydramnios indicates a possibility of aneuploidy, though triploidy and teraploidy may show oligohydramnios. A late onset IUGR with oligohydramnios indicates a chronic insult to the Uteroplacental circulation leading to fetal hypoxia. A normal amniotic fluid index suggests a pathology of a more acute origin.

      It is measured as largest vertical measurement of fluid pouch free of cord or fetal parts in four quadrants of the uterus.

      Thus diagnosis of IUGR is to be done by B mode assessment of the fetus. It is the management that is dependent on Doppler findings. Type I IUGR as already has been discussed is of fetal origin and therefore does not show significant vascular changes. It is type II and III IUGR in which vascular changes of the Uteroplacental bed and fetus are significant and so Doppler plays a major role in management of these two.

Prediction of PIH and IUGR:

      The first prediction of IUGR based on Doppler studies of the uterine and umbilical arteries can be done at 22-25 weeks.

      1. 22-24 weeks Doppler shows high resistance in uterine artery-24 fold increased chances of preeclampsia and IUGR

      2. Persistent early diastolic notch in the uterine artery waveform, increases predictive value of the Doppler study from 4.3% to 23% for IUGR and 68 fold increased risk of developing preecclampsia⁹.

      3. Sensitivity of the Doppler study increases to 80% in patients who would need to be delivered before 32 weeks i.e. patients who are likely to develop a server PIH and IUGR.

 Physiology:

This type of IUGR is chiefly due to compromised Uteroplacental circulation, so let us first briefly understand the same.

Normal umbilical artery waveform is the indicator of normal mother to fetus blood supply. Increase in umbilical artery flow velocities and decreased resistance are seen as the pregnancy advances normally and are due to:

Continuous maturation of placental villi.

Widening of placental vessels.

Continuous rise in fetal cardiac output.

Continuous changes in vessel compliance.

Continuous rise in fetal blood pressure.

As a result of lack of widening of some of the spiral arteries and the myometrial circulation, more pressure is required for the large quantities of blood to be flown through these vessels, leading o uterine artery resistance and notch and ultimately reduction in the umbilical artery flow.

IUGR can be divided into four periods of relatively well defined heamodynamic, biophysical and biochemical patterns and Doppler plays an important role in diagnosis and decision making

      The biochemical stages are hypoxemia, hypoxia and acidosis.

These can be physiologically staged as a silent period of increased resistance, a period of reduction in umbilical artery blood flow and centralization of fetal circulation and decentralization of fetal circulation.

Silent period of increased resistance

Pathophysiology:

            Till decrease in villous microcirculation upto 50%, no change is seen in the umbilical artery flow, if there is no defect in maternal supply & Doppler will show:

No change till 50% reduction for 3-6 weeks

Normal FVW in umbilical art, aorta and MCA

No extra study required if growth and umb. Art. Waveform is normal

Actually there is fetal hypoxemia with PO2 18-19mm Hg, pH 7.20-7.25

      Reduction in circulatory oxygen level then is sensed by peripheral chemoreceptors and leads to vagal stimulation of heart with preferential shift of cardiac circulation towards LV leading to increased umbilical artery resistance and low resistance (middle cerebral artery) MCA flow. As primary compensatory mechanism to hypoxemia, there is reopening of the ductus venosus to divert blood from liver and increase in the MCA flow in the distal segment for better peripheral cerebral circulation. Therefore:

Mild increase in umbilical artery PI is the cause of hypoxemia.

Abnormal MCA/fetal vessel FVW is the indication of the adaptation to hypoxemia.

Leading to, decreased MCA PI in sector 2, M1/M2 >1 & increased velocity & low resistance in ductus venosus. (DV)

Sometimes increased Aortic PI, but aortic and carotid chemoreceptors are mostly not affected. But hypoxemia is a result and not a cause of umbilicoplacental circulation abnormality, so low PO2 with no placental abnormality, no change in umbilical artery FVW.

The second phase is the phase of Hypoxia

      This can be divided into

      Initial phase

      Advanced phase

      Terminal phase

1. Initial phase:

Rise in umbilical artery PI but still positive flow throughout the cycle.

Presence of enddiastolic flow and decreased resistance in MCA

Umbilical artery PI/MCA PI: best indicator

Biophysical profile is unaltered or doubtful. (Biophysical score<7)

Lasts for 9-60 days, average of 2-3 weeks.

      Other progressive changes during this period are:

Reduce fetal respiratory and somatic movements

Reduced amniotic fluid index (5-8 cms)

Raised aortic PI

Raised renal artery PI

2. Advanced phase:

80% reduced villous circulation

Absent enddiastolic flow in umbilical artery (figure 8)

Absent enddiastolic flow in aorta leading to higher risk of necrotizing enterocolitis and intracerebral haemorrhages, thus increasing the morbidity and mortality.(figure 9)

Low MCA and CCA PI values (figure 10)

Loss of fetal reactivity is seen. Fetus is already suffering from a degree of hypoxemia and acidosis. Hypoxemia is seen in 70-80% of fetuses and acidosis may occur in 40-60% of fetuses. Absent aortic enddiastolic flow + altered heart rate response has a sensitivity for IUGR of 85% with a specificity of 80%.

3. Terminal Phase:

      This is a phase of acidosis.

Absent enddiastolic flow in umbilical artery.

Increasing resistance in MCA, due to cerebral oedema.

Absent diastolic flow in aorta.

IVC shows negative flow>12% and (figure 11)

Ductus venosus shows reversed flow or decreased telediastolic velocity values (figure 12)

Pulsating umbilical vein flow with apparent cyclical decrease in the flow (figure13)

These findings with reversed flow in hepatic vein and deceleration in heart rate are indications of acidosis. In worst cases coronary artery blood flow may also be seen.

Aortic isthmus flow:

      Aortic isthmus is the part of aorta, just beyond the origin of brachiocephalic trunk. This flow is usually a continuous positive flow with high velocity. Abnormality of this flow occurs about 2-3 weeks before he changes of hypoxia are seen in ductus venosus. Abnormal ductus venosus flow indicates high morbidity and mortality of the fetus. And therefore if delivery of the fetus is done after ductus venosus flow becomes abnormal he chances of fetal survival is very low. Therefore if the delivery can be done before this stage fetal survival and chances of its well being can be improved significantly. But at the same time fetus should not be delivered too early, to prevent risks of prematurity. Abnormal aortic isthmus flow is therefore found to be an important sign to decide the time of delivery.

      Obstetric management depending of Doppler findings:

IUGR with normal heamodynamic profile: No immediate action and repeat Doppler and BPP every 2 weeks.

IUGR with heamodynamic redistribution 32-34 weeks: early stage of centralization, Doppler and BPP monitoring. With latte stage of centralization, termination of pregnancy.

If IUGR with heamodynamic redistribution is seen between 28-32 weeks, termination of pregnancy with advanced and terminal stages of centralization but expectant management with early stage of centralization with Doppler and PVV monitoring every 5 days.

Same is true for the gestational age of<28 weeks. All chances are taken to allow the pregnancy to reach 30 weeks.

It must be remembered that as long as he fetal growth and the umbilical artery indices are normal, no further heamodynamic study is required and Doppler findings must be evaluated in conjunction with gestational age, fetal weight, liquor, biophysical profile, fetal activity, CTG.

      It is essential to know that the abnormal Doppler findings correlate well with the onset of abnormal heart rate patterns. Fetal hypoxemia is always reflected by reduced heart rate variation and heart rate decelerations¹⁰. Fetal academia reliably presents as very short term and low value variations in FHR, and precedes intrauterine death which corresponds with the increased ductus venosus PI, especially before 32 weeks and indicate more acute changes in the degree of abnormality. Delivery must be considered if one of these parameters are persistently abnormal (Hecher et al)¹¹.