D-Dimer Vs Serial Compression Ultrasound Study

Inclusion Criteria: * first suspected deep vein thrombosis * no previous venous thromboembolism * referred to thromboembolism outpatient clinic Exclusion Criteria: * comorbid condition limiting survival to less than six months * contraindication to venography (contrast allergy, etc.) * receiving long term warfarin therapy * receiving full dose heparin therapy for more than 48 hours * absence of symptoms during the five days immediately prior to presentation * symptoms of pulmonary embolism * pregnancy * geographic inaccessibility which precludes follow-up