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
