Venous Thromboembolism and Oral Contraceptives

Abstract

Recent studies of currently available oral contraceptives indicate that the risk of major sequelae is low in young women (aged between 20 and 24 years). Venous thromboembolism remains one event that can occur in users independent of the presence of risk factors. However, the attributable risk is small, with a range of approximately 7 to 18 events per 100 000 women annually. This risk is directly proportional to estrogen dosage starting at levels of 30-35 microg. The type of progestogen (progestin) may also influence risk, though recent studies are controversial. In particular, there is debate surrounding whether desogestrel and gestodene carry a greater risk of thromboembolism than levonorgestrel. Modifiable risk factors for venous thromboembolism include hemostatic disorders, especially factor V Leiden, and possibly obesity. Cigarette smoking is not a significant risk factor in oral contraceptive users. With the exception of avoiding oral contraceptive use among women with a either a personal history of venous thromboembolism or a strong family history (until evaluated for hemostatic abnormalities), and perhaps limiting the use of desogestrel- or gestodene-containing oral contraceptives, there is little clinicians can do to reduce the risk of this disorder.