Deep Venous thrombosis in pregancy period Causes & diagnostic modalities

Q.1:-What do we mean by the term venous thromboembolism (VTE) & is prevalence ?? Ans: VTE encompasses deep vein throm­bosis (DVT) and pulmonary embolism (PE). The incidence of VTE ranges from 0.76 to 2.0 episodes per 1,000 pregnancies and varies from country to county. Fortunately in our country VTE is relatively uncommon though DM & HTN are rampant. Admittedly, many cases remain undiagnosed and are treated as Resp distress (in post op period particularly), Moreover minor pulm embolism can often be self limiting. VTEs account for 9% of all maternal deaths in the United States.

Q.2: When VTE is more common & when PE is more common both being the expression of same pathology??  Ans:-Approximately 80% of all VTEs express as DVT in pregnancy period and  20% of all VTE are manifested as  PE . But  PE occurs more frequently postpartum.  . Approximately half of all VTEs occur in the antepartum period though Cesarean delivery imparts a three to five times greater risk than a vaginal delivery.

Q.3 :-What are the risk Factors for Venous Thromboembolism. Why VTE is more common in pregancy ? ??

Ans: Pregancy:--Pregnancy is considered a hypercoagulable state. Normal pregancy changes favours a hypercoagulable state e.g. due to rise of  1) Fibrinogen, 2) other coagulation factors, 3) and plasminogen activator inhibitor-1 (PA1-1) levels. All such components are raised.  By contrast  natural anticoagulants are decreased  like A)  free protein S levels, and B) fibrinolytic activity.

  Q.4: What may be other top up conditions to promote VTE in preg??  Ans:-One of the most significant risk factors is 1) a personal history of VTE. 2) Medl disorders like heart disease,  lupus, obesity, diabetes, and hypertension increase risk of thrombosis. 3) Recent surgery, 4) family history of VTE, 5) bed rest or prolonged immobilization, 6)  smoking, 7) age older than 35 years, 8) multiple gestations, 9) preeclampsia, and 11) postpartum infection also promotes thrombus formation.

The following associated conditions are now considered not an important cause of accelerated rate of VTE!! Such are Fetal death in utero, severe IUGR, abruption, and severe early-onset preeclampsia have been correlated with underlying thrombophilias that affect uteroplacental circulation. However, these are still  controversial and recent studies fail to reliably estab­lish causal links between thrombophilias and these adverse pregnancy outcomes.

 Q. 6 Kinds of thrombophilias ??  Thrombophilias may be inherited or acquired. Pregnancy may trigger an event in women with an underlying thrombophilia.

What goes wrong with her sice birth?? Causes of congenital / Inherited thrombophilias

  

Inherited thrombophilias are present in over half of all maternal thrombotic events. The causative congenital factors are 1) Antithrombin deficiency and 2) Homozygosity for factor V Leiden mutation are the most potent of the inherited thrombophilias. Double or compound het­erozygosities (for both factor V Leiden and 3) prothrombin G20219A) are also at greater risk of VTE. The prevalence at USA are as follows which hover do not match with our country

Factor V Leiden Homozygosity	34.4
Prothrombin G20210A Homozygosity	26.4
Factor V Leiden heterozygous	8.3
Prothrombin G20210A heterozygous	6.8
Protein C deficiency	4.8
Antithrombin deficiency	4.7a
Protein S deficiency	3.2
Methylenetetrahydrofolate reductase (MTHFR)	0.74
C677T homozygote
Factor V Leiden + prothrombin G20210A (compound	88.0
heterozygosity)
Antiphospholipid antibody syndrome	15.8

Acquired thrombophilias:

 Include A) persistent antiphospholipid antibody syndromes (APS) (lupus antico­agulants or Anticardiolipin antibodies). APS is present in 15% to 17% of women with recurrent pregnancy loss.

Routine screening for thrombophilias is not recommended in all pregnant women and screening indications are controversial. ACOG no longer recommends thrombophilia testing in women with recurrent fetal loss, placental abruption, IUGR, or preeclampsia but such work up may be  needed in following conditions:- A) Personal or family history of VTE (first-degree relative with VTE before age 50 years in absence of other risk factors). B) APS screening may be appropriate for women with repeated fetal losses (three losses <10 weeks’ gestation or one loss >10 weeks’ gestation of a mor­phologically normal fetus).

Q. 8:--What are the manifestations and Diagnosis of VTE??

1) VTE during pregnancy (workup to be done after delivery) or VTE associated with a non­recurrent risk factor such as prolonged immobilization. Over 70% of DVTs in pregnancy develop in the iliofemoral veins, which are more likely to embolize, and the majority are on the left side.

A)                      Clinical Diagnosis of DVT is diffi­cult in pregnancy because expected changes in pregnancy may mimic the symptoms of DVT. Additionally, many patients are asymptomatic. If symptoms exist, the most common include calf or lower extremity swelling, pain or tenderness, warmth, and erythema. Homan sign (calf pain with passive dorsiflexion of the foot) is present in <15% of cases, and a palpable cord is present in <10% of cases. Symptoms of an iliac DVT include abdominal pain, back pain, and swelling of the entire leg. In pregnant women with clinical suspicion of DVT, diagnosis is confirmed in <10%.

B)                       Venous duplex imaging, including compression ultrasound, color, and spectral Dop­pler sonography, has replaced contrast venography as the gold standard and is the most commonly available noninvasive diagnostic method, with a sensitivity of 97% and specificity of 94% in symptomatic proximal DVT. If the deep venous system is normal, the presence of a clinically significant thrombus is unlikely. Limitations include poor sensitivity for asymptomatic disease and difficulty in detecting iliac vein thromboses

C)  Magnetic resonance imaging (MRI): Studies in nonpregnant patients show a sensitivity of 100% and specificity of 98% to 99% for pelvic and proximal DVTs while maintaining a high accuracy in detecting below-the-knee DVTs.

D) D-Dimer test is a sensitive but nonspecific test for DVT; However, its use in preg­nancy is limited, as D-dimer normally increases with gestational age. A normal D-dimer result may be reassuring if clinical suspicion is low.