Heparin prophylaxis for deep vein thrombosis and pulmonary embolism.

Thromboembolic prophylaxis remains a significant problem and is obviously incompletely understood. It would appear, however, that at present the information available implies several points. First, administration of low-dose heparin is efficacious in preventing deep vein thrombosis and pulmonary emboli in most general surgical patients who are at risk for thromboembolic complications. Second, low-dose heparin probably works by augmenting the effect of the naturally occurring inhibitor to Factor Xa. Third, patients in whom surgical operations are done and extensive tissue dissection or postoperative immobilization (such as hip arthroplasties) is required are probably not protected by low-dose heparin administration; full anticoagulation with warfarin or treatment with one of the platelet antiaggregating agents should be carried out. Fourth, any form of anticoagulation carries some risk of bleeding complications, but it appears that the incidence of major bleeding complications is not significantly greater in the treatment groups.