Deep venous thrombosis: Complete lower extremity venous US evaluation in patients without known risk factors - Outcome study

PURPOSE: To determine the diagnostic value of venous ultrasonography (US) t hat includes examination of calf veins in symptomatic patients suspected of having deep Venous thrombosis (DVT) of the lower extremities. MATERIALS AND METHODS: A retrospective cohort study of the prevalence of DV T included 977 consecutive patients with possible DVT but without known ris k factors for DVT. Color flow and compression US were performed. The outcom e was the frequency of overlooked, clinically important DVT after negative initial results from bilateral venous US of above- and below-the-knee veins . patient records (904 patients), mailed questionnaires (61 patients), and telephone contacts (12 patients) were used to establish a diagnosis of clin ically relevant DVT. RESULTS: The prevalence of DVT was 15% (142 of 977), with DVT-in 15% (21 of 142) restricted to the below-the-knee veins. Follow-up (median, 34 months) in 835 patients with negative US findings showed one occurrence of venous thrombosis (superficial thrombophlebitis) during the first 3 months of foll ow-up. Three other cases of venous thrombosis occurred at 17, 18, and 48 mo nths of follow-up but were believed not to be linked to the initial complai nt. The incidence of overlooked DVT was 0% (95% CI, 0.0%, 0.4%). CONCLUSION: In patients without risk factors for DVT, a negative venous US study can help exclude the presence of clinically important DVT if the exam ination includes careful evaluation of the calf veins.