CONGENITAL THROMBOPHILIA

The heritable defects which are at present accepted as proven to be as sociated with familial venous thrombosis are deficiency of antithrombi n (AT), protein C (PC) or protein S (PS) and the FV Leiden mutation. I n women from symptomatic kindred each of these defects is associated w ith increased risk of pregnancy-associated venous thrombosis and incre ased risk of fetal loss and other vascular complications of pregnancy. The risks appear to be greatest for some types of AT deficiency. Thes e defects are very common but there is growing evidence that congenita l thrombophilia is a multigene defect and abnormalities of AT or of th e PC-PS system represent only part of the genetic thrombotic predispos ition in symptomatic families. Currently it seems reasonable to focus resources on women with AT or PC-PS system abnormalities who are thems elves already symptomatic or who come from symptomatic families rather than screen whole populations for these defects. In symptomatic famil ies screening of females around the time of puberty allows time for ed ucation and counselling, Pregnancies should be planned, and each pregn ancy in each patient managed individually. In general though, women wi th AT deficiency from symptomatic families require anticoagulant proph ylaxis throughout pregnancy and for at least 3 months post-partum, whe reas these with PC-PS system defects may require third-trimester plus post-partum prophylaxis or post-partum anticoagulant prophylaxis only.