Inherited thrombophilia and pregnancy associated venous thromboembolism

doi:10.1136/bmj.39205.484572.55

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Wendy Lim, assistant professor1,
John W Eikelboom, associate professor2,
Jeffrey S Ginsberg, professor of medicine3

¹Department of Medicine, McMaster University, St Joseph's Hospital
²Department of Medicine, McMaster University, HGH McMaster Clinic, Hamilton, ON, L9K 1H8, Canada
³McMaster University Medical Center

Correspondence to: J W Eikelboom eikelbj{at}mcmaster.ca

Pulmonary embolism is the leading cause of maternal mortality in developed countries and accounts for 20% of pregnancy related deaths in the United States.1 2 The risk of pulmonary embolism and deep vein thrombosis, collectively known as venous thromboembolism, is increased during pregnancy and is further increased by the presence of inherited or acquired thrombophilias. We summarise the epidemiology and diagnosis of venous thromboembolism in pregnancy and discuss the anticoagulant management of women with inherited thrombophilia who are at risk of, or who develop, venous thromboembolism during pregnancy and the postpartum period.

Scenario

A 30 year old woman, a known heterozygote for the factor V Leiden mutation, presents at eight weeks' gestation in her first pregnancy wondering whether she should receive prophylactic anticoagulation to prevent recurrent venous thrombosis during pregnancy. Several years ago she developed a deep vein thrombosis of the left leg after an ankle fracture and prolonged immobilisation and was found to have the factor V Leiden mutation. The deep vein thrombosis was treated with anticoagulants for three months, and the woman has had no recurrent thromboembolic events since stopping warfarin. Her mother developed a deep vein thrombosis after surgery but did not undergo testing for thrombophilia.

Methods

We searched Medline and the Cochrane database of systematic reviews for studies evaluating the epidemiology, diagnosis, prevention, and treatment of venous thromboembolism during pregnancy and the postpartum period in women with inherited thrombophilia, using the key words “venous thrombosis”, “deep vein thrombosis”, “pulmonary embolism”, “pregnancy (complications)”, “thrombophilia”, and “anticoagulants.”

How common are thromboembolic complications among pregnant women?

Venous thromboembolism occurs in 10 per 100 000 women of childbearing age and affects 100 per 100 000 pregnancies.3 Inherited thrombophilia is present in 30%-50% of women with pregnancy associated venous thromboembolism,3^w1 with factor V Leiden being the most frequently identified inherited thrombophilia in the white population (table 1⇓).