USMLE Step 2 CK Lecture Notes 2019: Obstetrics/Gynecology (Kaplan Test Prep)

(Kiana) #1

THROMBOPHILIAS


A   26-year-old G4  P1  Ab2 woman   comes   in  for her first   prenatal    visit   at  8
weeks’ gestation by dates. Her first pregnancy was a spontaneous first-
trimester loss, for which she underwent a D&C. In her second pregnancy
she developed right lower extremity deep venous thrombosis at 29 weeks,
which was followed by an unexplained fetal demise at 30 weeks. Labor was
induced with PGE2. The fetus was normal in appearance, without
congenital anomalies. Autopsy on the fetus was unremarkable. Her last
pregnancy was also a spontaneous first-trimester loss. Her sister has a
history of recurrent deep venous thrombosis.

The thrombophilias are disorders which promote blood clotting due to an excess
of clotting factors or a deficiency of anticlotting proteins that limit clot
formation. Prevalence is as high as 20% of the population, but most individuals
are asymptomatic. Some will develop deep vein thrombosis or venous
thromboembolism (VTE) that can become life-threatening.


Risk factors include immobilization, surgery, or pregnancy. Pregnant women
with a thrombophilia are also at higher risk than other pregnant women of
developing a VTE.


Pulmonary embolus is the leading cause of maternal death in the United States;



50% of pregnant women who develop a pulmonary embolus or other VTE have
an underlying thrombophilia.


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