ACOG committee opinion no. 556: Postmenopausal estrogen therapy: route of administration and risk of venous thromboembolism.

The development of menopausal symptoms and related disorders, which lead women to seek prescriptions for postmenopausal estrogen therapy and hormone therapy, is a common reason for a patient to visit her gynecologist, but these therapies are associated with an increased risk of venous thromboembolism. The relative risk seems to be even greater if the treated population has preexisting risk factors for venous thromboembolism, such as obesity, immobilization, and fracture. Recent studies suggest that orally administered estrogen may exert a prothrombotic effect, whereas transdermally administered estrogen has little or no effect in elevating prothrombotic substances and may have beneficial effects on proinflammatory markers. When prescribing estrogen therapy, the gynecologist should take into consideration the possible thrombosis-sparing properties of transdermal forms of estrogen therapy. As part of the shared decision-making process, the gynecologist should weigh the risks against the benefits when prescribing combination estrogen plus progestin hormone therapy or estrogen therapy and counsel the patient accordingly.