Oral Contraceptive-Associated Thromboembolism. A Retrospective Analysis of Thrombophilic Work-out and Long Term Follow up in 57 Cases

Introduction: The increased risk of venous thrombosis in women taking oral contraceptives (OCs) has been recognized since the early 1960s. Coexistence of hereditary risk factors appears to have an additive effect. Women under OCs that carry the factor V Leiden mutation have a 35-fold increased risk of thromboembolic events compared to women without the mutation who are not on OCs. Evaluation of family and personal history is the mainstay of prophylaxis prior to OC administration, but often family thrombophilia or thromboembolic (TE) events are not reported prior to OCs prescription.

Patients-Methods: Fifty-seven women with a median age of 28 (21–48) years, which suffered OC-associated TE, were studied. The median period of OC therapy prior to TE event was 2 months (0.5–60). Fifty-five of them experienced VTE while 2 suffered stroke. Leg thrombosis was the most common clinical finding [37/55 (67,2%) patients] Apart from personal and family history, Thrombophilia investigation included measurement of : serum Homocysteine, Antithrombin, Protein C and S, Lipoprotein (a), Activated Protein C (APC) resistance, antiphospholipid antibodies and lupus anticoagulant. In addition the presence of FV Leiden, FII 20210 GA mutations and MTHFR 677 CT polymorphism were determined.

Results: A high prevalence of the factor V Leiden mutation was detected in the study group; 50% had APC-resistance test positive, 26 (45%) patients were found to be heterozygous and 3 (5,2%) homozygous for the FV Leiden mutation. Lp(a) elevation was observed in 19,3% and Homocysteine elevation in 15,8% of patients. In 9 women (15,8%) both family history and thrombophilic profile were negative. Serious VTE events (2 abdominal and 6 CNS thromboses) were observed only in the Leiden subgroup. During the follow up period ranging from months to 18 years, 3 women (6,25%) experienced a miscarriage and 14 suffered additional VTE events (25%) and they are currently on permanent anticoagulation.

Conclusions : Universal thrombophilia screening of women prior to prescription of OCs is not advisable as it does not appear to be cost effective. However, screening certain subgroups, such as women with a known personal or family history, may be of great value. If a full thrombophilic profile can’t be performed, a mere activated protein C resistance test, that reflects the presence of the factor V Leiden mutation, may provide an easy and cheap way of identifying and consulting properly women at higher risk for VTE prior to OC use. Women with OC-associated VTE and thrombophilia carry a substantial recurrence risk that persists for years.