Venous Thromboembolism in Pregnancy

Abstract

Venous thromboembolism (VTE) is the leading nonobstetric cause of maternal morbidity and mortality. The risk for deep venous thrombosis (DVT) commences in the first trimester with a striking proclivity for the left lower extremity. Pulmonary embolism (PE) is more frequent in the postpartum period. Activated protein-C resistance increases the risk of VTE 30- to 50-fold in heterozygotes and several hundred-fold in homozygotes. Other inherited and acquired factors also increase the risk.

The diagnosis of DVT and PE is even more difficult in pregnancy because of the common occurrence of leg edema, leg pain, and dyspnea. VTE requires objective proof: (1) DVT-positive duplex ultrasound or impedance plethysmography and (2) PE-positive noninvasive lower extremity study, a high-probability perfusion lung scan (normal excludes PE), or a pulmonary angiogram. Concern over fetal radiation from these diagnostic studies is not warranted. Initial treatment of VTE is the same as in the nonpregnant patient. However, warfarin should not be used. In its place, low-molecular-weight heparin or unfractionated heparin should be given for the duration of pregnancy; warfarin should be given for at least 6 weeks postpartum or for ≥3 months. The indications for VTE prophylaxis are discussed.

Key Words:

deep venous thrombosis - embolism - pulmonary embolism - heparin