Epidemiology, risk factors and prophylaxis of venous thrombo-embolism in obstetrics and gynaecology.

Venous thrombo-embolism remains a major cause of mortality and morbidity following gynaecological surgery and in association with pregnancy and delivery. Specific risk factors can be identified pre-operatively and before or during pregnancy and delivery. Clinicians and units should develop guidelines for risk assessment and the implementation of specific thromboprophylactic measures in patients considered to have significant risk. The main prophylactic techniques are unfractionated and low-molecular-weight heparins and physical methods such as graduated elastic compression stockings. It should be noted that there are particular concerns with regard to the use of pharmacological thromboprophylaxis with both heparin and warfarin in pregnancy. Unfractionated heparin is associated with osteoporotic problems, allergy and heparin-induced thrombocytopenia which can cause significant thrombotic problems. Warfarin is associated with teratogenesis and the risk of bleeding in mother and fetus. Clearly, where antenatal thromboprophylaxis is to be used, the risk of the anticoagulants employed must be weighed against the potential benefits. Such assessment might be best done prior to pregnancy in order that the patient can enter pregnancy with a clear view of the potential hazards and benefits. Low-molecular-weight heparins are being increasingly used in pregnancy but it is unclear to what extent they are safer than unfractionated heparins. However, they do appear to have substantially less risk of heparin-induced thrombocytopenia and possibly less risk of heparin-induced osteoporosis. Increasingly, thrombophilia is recognized as underlying many thrombotic problems, particularly in young women, and when the events occur in association with pregnancy. In view of the complexity in the management of such patients, it is important that they be referred to a unit with specific expertise in the management of thrombophilia.