Is it useful to also image the asymptomatic leg in patients with suspected deep vein thrombosis?
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BACKGROUND: Venous ultrasonography is the cornerstone of the diagnostic work-up in patients with suspected deep vein thrombosis (DVT). Significant variations exist in clinical practice between centers and/or countries, e.g. proximal vs. whole-leg ultrasound, serial tests vs. single test, and combination with clinical probability and D-dimer testing. Fewer data exist on the need for bilateral leg imaging. OBJECTIVES: To assess the yield of bilateral leg ultrasonography in patients with suspected DVT. PATIENTS AND METHODS: This was a retrospective cohort study of consecutive patients with clinically suspected DVT. A single whole-leg ultrasound scan was performed in all patients. We extracted information on demographics, risk factors, clinical signs, pretest probability, side of clinical suspicion, and ultrasound results. RESULTS AND CONCLUSIONS: Among the 2804 included patients, 609 (21.8%) patients had a positive ultrasound finding. A total of 20 patients (0.8%; 95% confidence interval [CI] 0.5-1.2%) had a thrombus diagnosed in both the symptomatic leg and asymptomatic leg. Moreover, five patients (0.2%; 95% CI 0.1-0.5%) did not have a thrombus in the symptomatic leg but had a thrombus in the asymptomatic leg. Two of 2540 patients with unilateral symptoms had no proximal DVT in the symptomatic leg and a proximal DVT in the asymptomatic leg (0.08%; 95% CI 0.0-0.3%). In summary, systematic imaging of both legs in patients with suspected DVT has a very low yield, and therefore does not appear to be justified.
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