Deep vein thrombosis.

Deep vein thrombosis (DVT) is a common condition. Most cases arise as complications during the perioperative period. This can largely be prevented by adequate prophylaxis, principally using low-dose subcutaneous heparin. Only a minority of DVTs produce serious complications, but it is not currently possible to predict the clinical behaviour of any DVT, once formed. For this reason, any identified DVT should be vigorously treated. The mainstay of treatment remains systemic anticoagulation with heparin and then warfarin. Warfarin should be continued for 1 month in postoperative cases and 3 months in spontaneous cases, provided there is no ongoing predisposing factor. Recurrent spontaneous DVT formation is an indication for lifelong anticoagulation. Recent evidence suggests that the subcutaneous route of administration of heparin has advantage over traditional intravenous infusion. Some large DVTs require thrombolysis, and it is now possible to treat the underlying anatomical defects with angioplasty and endovascular stenting, although the long-term outcome of these procedures has not yet been established. For patients with contraindications to the use of anticoagulants, a variety of (temporary and permanent) percutaneously inserted vena caval filters are now available. The principal complications of DVT are pulmonary embolism, which may be fatal, and the development of a postphlebitic leg. The avoidance of these depends on adequate prophylaxis and vigorous treatment of the primary DVT.