[Deep venous thrombosis in pregnancy: risk factors and possibilities for prevention].

Twenty-two cases of acute venous thrombosis in pregnancy (0.64%) were studied. Concomitant pulmonary embolism was documented in 0.23%. Prophylactic heparinization was performed in 32 gravidae. In the acute thrombosis group therapy was instituted in the 26th week, and in the prophylaxis group in the 20th week of pregnancy. Recurrent thromboses after cesarean section occurred in 4.5% of the patients with acute venous thrombosis and in 5.6% of those in the prophylaxis group. Reduced red blood cell deformability, low antithrombin III and high leukocyte count were identified as risk factors. Heparinization did not prevent increased red blood cell aggregation and plasma viscosity at birth. Rheologic factors played only a secondary role in the prophylaxis group. Prophylactic heparinization in pregnancy is currently the only means of reducing the thrombosis recurrence rate in patients with a history of thromboembolism.