A prospective study of the efficacy of B-scan sonography in the detection of deep venous thrombosis in the lower extremities.

Between 1 July and 31 December, 1985, 53 patients, clinically suspected of having deep venous thrombosis (DVT), were prospectively studied by B-scan ultrasound prior to lower-limb venography. Criteria for a positive ultrasound examination included visualization of frank clot, failure of the vein to collapse with compression, and absence of normal phasic flow with pulse Doppler sampling. All (100%) of the contrast venograms were considered of diagnostic quality. Fifty of the 53 ultrasound examinations (94%) were considered diagnostic. Of the 50 patients having venous ultrasound of diagnostic quality, contrast venography was positive in 25 and negative in 25 for DVT. Venous ultrasound was correct in 46 patients, for an accuracy of 92% (46/50). Sensitivity was 88% (22/25), specificity was 96% (24/25), the positive predictive value was 96% (22/23), and the negative predictive value was 89% (24/27). The single most useful sign of thrombosis in ultrasound examinations was the failure of the involved vein to collapse with compression. Venous ultrasound appears to be highly accurate in the detection of deep venous thrombosis of the lower extremity.