Use of selective factor V Leiden screening in pregnancy to identify candidates for anticoagulants.

Abstract

To improve identification of gravidas at risk for thrombosis. Venous thromboembolic complications are a major cause of maternal mortality during pregnancy. Factor V Leiden, which causes activated protein C resistance, is the most prevalent thrombophilia in white populations. However, selective screening for factor V Leiden has not been evaluated previously for identifying women who might benefit from anticoagulant prophylaxis during pregnancy. We constructed a risk score based on major risk factors such as overweight, family history of thrombosis, previous thrombosis, cesarean delivery, and preeclampsia. A cohort of 2384 women with known factor V Leiden status was studied. Using the risk score and its distribution, we explored possible strategies of doing selective testing for factor V Leiden and their consequences. During the postpartum period, but not antepartum, there is a possibility of identifying women at similar risk as those with a history of thrombosis. Women with a risk score of 2 (4% of women, 0.2% risk of thrombosis) would be screened for factor V Leiden, and those with a resulting risk score of at least 3 (ie, 1.2% risk of thrombosis) would be treated for 6 weeks. Theoretically, for every 83 women treated at this risk level, one thrombotic episode might be prevented. By using a risk score, a subgroup of women who could benefit from selective factor V Leiden screening were identified postpartum.