Venous thromboembolism: diagnosis and management of deep venous thrombosis.

Venous thromboembolism (VTE) affects 1-2 per 1000 people in the general population each year. Clinical diagnosis of deep venous thrombosis (DVT) is unreliable, and must be confirmed by compression ultrasonography or venography. A low clinical pretest probability of DVT and negative D-dimer result reliably exclude the diagnosis, with no need for diagnostic imaging. Initial treatment of DVT is with low-molecular-weight heparin or unfractionated heparin for at least 5 days, followed by warfarin (target INR, 2.0-3.0) for at least 3 months. A vena cava filter is indicated in patients who are ineligible for anticoagulant therapy or who experience embolism despite therapeutic anticoagulation. Thrombolysis or surgical embolectomy may be used as a limb-saving measure in patients with extensive proximal DVT and circulatory compromise that threatens the viability of the leg. Decisions regarding the optimal duration of anticoagulation to prevent recurrent VTE should be individualised and balance the risk of recurrence if warfarin is stopped against the risk of major bleeding and inconvenience of continuing treatment. The risk of recurrence is highest in people with recurrent unprovoked DVT or chronic predisposing factors (eg, cancer) who require indefinite anticoagulant treatment.