Ultrasound-Based Diagnostic Strategies for Deep Vein Thrombosis

To the Editor: In their randomized controlled trial, Dr Bernardi and colleagues¹ found equivalent safety for 2 ultrasound-based diagnostic strategies for managing outpatients with suspected deep vein thrombosis (DVT). The results of the study deserve some comments.

First, for the 2-point strategy the prevalence of proximal DVT detection on the second ultrasound test was 5.5% (14/256). This is much higher than has been previously reported. For example, in the study by Cogo et al,² which included more than 1700 patients with suspected DVT, this rate was less than 1%.² It has been suggested that the second ultrasound test is of limited added value, and strategies have been proposed using a single proximal venous examination, which proved to have an acceptable 3-month thromboembolic rate.³ However, the use of a single proximal vein ultrasonography might be criticized if the prevalence of proximal DVT detected at the second ultrasound test is as high as 5.5%. The high prevalence of cancer in this study (30%) may account for the high rate of proximal extension, indicating a need for particular care when choosing a diagnostic strategy for cancer patients.