New developments in the prevention and treatment of venous thromboembolism.

Although unfractionated heparin has been widely used for preventing and treating venous thromboembolism, low-molecular-weight heparins (LMWHs) have been extensively studied. In particular, LMWHs have been valuable in the prevention of venous thromboembolism in high-risk surgical patients, such as those undergoing total joint replacement, and in high-risk medical patients. Recent studies indicated that the extended use of LMWHs after discharge in patients undergoing total hip replacement significantly decreases the frequency of venous thrombosis compared with placebo. Furthermore, LMWHs have been shown to be as effective and safe as unfractionated heparin for the initial treatment of both deep vein thrombosis and pulmonary embolism and have extended the treatment of these conditions into the outpatient setting. New recommendations from the sixth American College of Chest Physicians Consensus Conference on Antithrombotic Therapy and the rationale for change are discussed.