Thrombophilia and DVT

What are thrombophilias?? Ans:-It is a deficiency disorder (acquired or congenital):  : A number of isolated  deficiencies of proteins   involved    either A)  in coagulation  inhibition or   B)   Fibrinolytic system in the fibrinolytic system – collectively    referred  to a thrombophilia - . This can cause a o hyper coagulable state of affair. Some of them may lead to  recurrent venous   thrombo embolism .

What is called   Milk leg??  The other terminology is   phlegmasia alba dolens ( milk leg)-a kind of . DEEP VENOUS THROMBOSIS

 The signs    and symptoms of deep venous thrombosis involving the lower   extremity vary greatly depending    upon the degree of occlusion    and   the intensity of  the  inflammatory    response. Clinical puerperal thrombo philebitis involving   the lower   extremity   is abrupt in onset with severe pain and edema of the leg and   thigh. The thrombus typically    is left sided     and involves    much of the deep venous   system from the foot   to the iliofemoral region. Occasionally     reflex   arterial spasm causes     a pale cool extremity with diminished   pulsations-  so called phlegmasia alba dolens or milk leg.

What clinical conditions may mimic DVT but such conditions are nonthrobotic?? Ans Non thrombotic    conditions   are often demonstrated   that  explain   the clinical findings  that originally   suggest  venous thrombosis    Some  examples  include   cellulites,  edema,   hematomas   and  superficial  phlebitis.

What about Calf pain??  Most of DVT are asymtomatic because many a clot in deep veins of leg or thigh  though  there may be appreciable volume of clot   yet such clot cause  little    reaction in the form of pain , heat   or swelling      . Ans:-   calf pain is not specifc and may not be present at all and thereby causing no symptom , But pain in  the affected leg may be evoked by many causes like 

a)                 in response   to squeezing or b)  to stretching   the Achilles tendon   may be caused by  c)  or a strained    muscle   d)  a contusion f) or  thrombosis    . The latter may be    common   during the early puerperium as the consequence of   inappropriate   contact   between the calf   and the delivery  table leg  holders.

How to diagnose DVT ??  1) Compression ultrasonography    used along with duplex    color Doppler    ultrasound a the primary    test currently  used to detect   proximal  DVT. But  the limitation of    ultrasonography    used along with duplex    color Doppler    ultrasound    is this procedure  results do   not necessarily rule out pulmonary embolism frequently   originates in the iliac   veins.

Although  2)    venography  remains  the standard for confirmation of DVT  non invasive methods have largely   replaced these tests  to confirm    the clinical   diagnosis. 3) Magnetic    resonance imaging   is reserved   for specific   caes in which   the ultrasound    findings are equivocal or  with negative   ultrasound findings    but strong clinical suspicion. This   technique   allows for excellent delineation  of  anatomical   detail above   the inguinal ligament   and phase   images can be used  to diagnose   the   presence or absence   of pelvic   vein flow. An additional    advantage   is   the ability to image   in coronal   and sagittal   planes. 4) CT Scan:-Computed tomographic  scanning     may also be  used to assess the  lower   extremities  . It is   widely available     but requires   contrast   agents   and ionizing    radiation. As   discussed in Appendix   C , radiation exposure  to the fetus   is negligible unless the  pelvic  veins  are imaged.

Superficial  venous thrombosis

Thrombosis   limited strictly to the superficial veins   of the saphenous system is   differentiated   from DVT   and treated with analgesia elastic   support and rest . If  it does   not soon   subside or if deep   venous involvement   in suspected   appropriate  diagnostic    measures art taken and    heparin   is given if deep  vein  involvement   is confirmed superficial thrombophlebitis is typically seen in association   with superficial   varicosities   or as  a sequela to intravenous catheterization .

Management of DVT :- Which agent?? Ans: anyone like  either unfractionated  heparin or with low molecular   weight   heparin. Having said that treatment    of DVT  consists  of anticoagulation limited activity   and analgesia . For  all women during either   pregnancy   or postpartum initial    anticoagulation is with  either unfractionated  heparin or with low molecular   weight   heparin.  For women    during pregnancy    heparin  therapy   is continued and for those postpartum  warfarin    therapy  is given.

Most often   pain is promptly   relieved    by these   measures    . After   symptoms   have  completely  abated graded   ambulation  should be  started  with the legs fitted with   elastic  stockings and anticoagulation   continued   . Recovery   to this stage  usually   takes about 7 to  10 days.

Therapeutic dose Heparin

Treatment   of acute attack (not prophylaxis) :-thromboembolism  during pregnancy  begins with an  intravenous  heparin   bolus   followed by continuous infusion     titrated to achieve  full anticoagulation. There    are  a number of protocols   to accomplish   this . Intravenous    anticoagulation    should be maintained for at least 5 to 7 days  after which   treatment    is converted to    subcutaneous heparin Injections are given every     8  hours to prolong    the partial thromboplastin    time to at  least   1.5 to 2.5  times    control throughout   the    dosing    interval. Treatment is continued for at least    3 months after the   acute  event.

 If the  woman is still pregnant    at  this juncture   it is not known whether   it is better   to continue   with a therapeutic or a  prophylactic dose of anti coagulate   for the reminder of pregnancy.

Complications of heparin therapy include thrombocytopenia osteoporosis and hemorrhage. There are   two types   of thrombocytopenia   associated  with heparin   use. The most    common type of heparin induced   thrombocytopenia   is a  non immune benign  reversible    form that occurs within the    first few days   of therapy  and resolves  in 5 days  without cessation of therapy  . The  more severe   form of HIT   results from an immune    reaction involving   IgG   antibodies   directed   against  complexes  of platelet factor  4  and heparin . Osteoporosis develops   with long   term   administration   and is more    prevalent   in cigarette smokers. In an   attempt to avoid severe   osteoporosis    women   treated   with heparin   should   be encouraged to take supplemented calcium  of vitamin d

Low   Molecular weight  Heparin

This is a family of derivatives of   unfractionated heparin and   their   molecular   weight   average 4000  to 5000 daltons compared    with about 12,000   to 16,000   daltons   for conventional heparins. Like    standard heparin low molecular    weight heparin do not     cross the placenta.

Lovenox warned   that its  use in pregnancy had been   associated   with congenital   anomalies  and as increased risk of   hemorrhage   . concluded   that  enoxaparin   and dalteparin  could be given  safely   during pregnancy. One  caveat    is that  low molecular    weight   should  not be used in patients with prosthetic heart   valves  because of reports   of valvular thrombosis   . Their    use may increase   the risk of spinal   hematoma  associated  with    regional    analgesia. Finally  given within  2 hours  of cesarean delivery    these agents   increase   the risk of wound hematoma.

Warfarin

Anticoagulation  with warfarin derivatives is generally  contraindicated   during pregnancy. These   drugs readily   cross the placenta    and cause fetal   death and malformation from hemorrhages. They are  safe     however    when ingested   while  breastfeeding . Postpartum  venous thrombosis can be  treated with intravenous heparin   and oral warfarin initiated simultaneously and heparin    can usually   be discontinued after 5 days  Postpartum women  have been   shown to require    a significantly  larger median total   dose   of warfarin compared to non pregnant   controls and a longer time    to achieve  the target   international    normalized ratio   after  delivery   most women    are anti coagulated  with warfarin for at least 6 weeks.

PULMONARY  EMBOLSIM

Although  it caused about 10 percent of maternal deaths  pulmonary   embolism   is relatively uncommon during pregnancy  and the puerperium. The incidence   averages about  1 in 7,000  pregnancies  with an   almost equal prevalence  for  antepartum and postpartum embolism. Clinical evidence  for DVT of the legs precedes pulmonary   Embolization in about   70 percent  of cases. In others especially  those that  arise   from deep   pelvic   iliac veins   the women   usually is asymptomatic  until symptoms of Embolization develop.

Physical  signs associated with pulmonary   embolism may   include as accentuated pulmonic closure sound rales    or friction rub . Right Axis deviation may  or may not be   evident on the  electro cardiogram . Even with massive pulmonary  embolism   signs symptoms  and laboratory  data to support  the diagnosis    may be deceivingly non specific.

Diagnosis

As with deep   venous  thrombosis   the diagnosis  of pulmonary   embolism requires   an initial high   index of suspicion  followed by objective   testing  . A chest   radiograph should be  performed if there is  underlying  suspicion  for other diagnosis . In many   centers  spiral  computed    tomography  has   replaced  the more cumbersome ventilation perfusion  lung scan .

These scans utilize   a small   dose of a radioactive    agent usually . Tc macro aggregated albumin which   is  administered intravenously  . There is  negligible  fetal  radiation   exposure  . the scan may   not provide  a definite  diagnosis  because  many   other conditions – for example pneumonia  or local   bronchospasm- can  cause   perfusion   defects.  Ventilation scan   with inhaled Xe  or Tc   are added  to perfusion   scan  in the  hope   that ventilation will be  abnormal  but perfusion normal    its  areas of pneumonia or hypoventilation . Thus   although ventilation scanning      increases  the probability     of an accurate   diagnosis   of pulmonary    embolus  in patients   with large   perfusion    defects  and   ventilation    mismatches normal    ventilation perfusions  does not   rule out pulmonary    embolism.

Spiral  computed tomography

Helical  computed  tomography       or spiral CT  allows  rapid imaging   from  the main pulmonary   arterials to at least the segmental and possibly  the sub segmetnal  branches . Fetal      radiation      exposure     with standard   single detector    spiral CT is less than with V/Q   lung scanning

We now use multi detector     spiral   CT as first    line evaluation of pregnant  women at parkland  Hospital  Although    the technique   has many advantages   we have found that the  better resolution allows  detection of previously   inaccessible  small distal  emboli that have    uncertain   clinical  significance.      DVT & PE:-Pregnancy   and the puerperium are considered  at one of the  highest   risks for otherwise healthy women to develop venous   thrombosis    and pulmonary   embolism. Indeed  thrombotic  pulmonary   embolism  caused nearly 9 percent    of the almost  623   pregancy  related    deaths in the United States during 2005.

The incidence  of all thromboembolism      is approximately  1 per 1000   pregnancies. About   half are identified antepartum and the other half    in the puerperium. Stasis is probably the  strongest   single predisposing event to  deep  venous thrombosis the frequency  of  which has decreased   remarkably  during the puerperium as early  ambulation has   become widely practiced .