Thromboembolic complications of pregnancy.

Physiologic changes in clotting parameters and venous flow during pregnancy increase the likelihood of deep venous thrombosis. Conditions that place the pregnant patient at a higher risk include a previous history of thromboembolic disease and surgery or bedrest for any reason during the pregnancy. In the high-risk patient, prophylactic therapy with low-dose heparin is advised beginning around the 34th week of pregnancy and continuing until 4-6 weeks after delivery. The clinical diagnosis of thrombophlebitis or pulmonary embolus is unreliable and should be confirmed objectively before therapy is started. During pregnancy, doppler ultrasound and impedance plethysmography should be the first-line diagnostic tests, but one should seek confirmation with venography if in doubt. The preferred method of therapy for the acute thrombolic event is full anticoagulation with continuous intravenous heparin from 7-10 days, followed by therapy with subcutaneous heparin for the remainder of the pregnancy and the puerperium, although there is considerable controversy regarding long-term therapy. Fibrinolytic agents have little place in pregnancy, and surgical therapy should be reserved for the critically ill patient only.