Venous thrombosis. Lifting the clouds of misunderstanding.

Deep venous thrombosis (DVT) is often occult and difficult to recognize clinically. The diagnostic approach should begin with color-flow (duplex) ultrasound, noninvasive functional tests such as plethysmography, or both. Because these tests are not 100% sensitive, contrast venography or magnetic resonance imaging may be necessary in a patient with unexplained symptoms. A baseline ventilation-perfusion scan should be considered for any patient with DVT, because there is a high incidence of clinically inapparent pulmonary embolism. In the absence of contraindications, systemic or regional thrombolytic therapy should be considered for every patient with acute DVT. Surgical thrombectomy may be indicated for patients with a large, obstructive proximal thrombus. At a minimum, routine treatment should start with heparin and proceed to oral warfarin (Coumadin, Panwarfin, Sofarin), which should be continued for 3 months. Recurrent DVT after cessation of therapy warrants lifetime use of anticoagulants. A filter should be placed in the inferior vena cava whenever a large, poorly adherent thrombus is identified or when there is progression of thrombosis despite an anticoagulant regimen.