Venous ultrasonography in the detection of proximal vein thrombosis after total knee arthroplasty.

A prospective study of the accuracy of real-time B-mode ultrasonography in detecting deep venous thrombosis in the proximal veins of the lower extremity was conducted in a consecutive series of total knee arthroplasty (TKA) patients. Ascending venography was used as the diagnostic standard. Ninety-six consecutive TKA procedures performed in 68 patients were considered. Eight extremities were excluded because paired ultrasonic and venographic studies were not performed. Eighty-eight extremities in 61 patients had paired studies (bilateral venous ultrasonography of the proximal veins and venography of the operated extremity), and were done at an average of eight days postoperatively. Both tests were done within 24 hours of each other (98% on the same day) and the radiologist and ultrasound technologist were blinded to the results of the others' study. Both tests were negative for proximal (common femoral through the popliteal vein) thrombosis in 72 extremities. Ten extremities had positive-paired tests for proximal thrombosis that correlated for thrombus size and location. There were five false-negative and one false-positive ultrasound studies for a sensitivity of 67%, a specificity of 99%, and an overall accuracy of 93%. Considering the 54 extremities that were examined after the vascular laboratory had gained considerable experience in venous imaging, the ultrasonic sensitivity, specificity, and overall accuracy rose to 83%, 100%, and 96% respectively. The authors believe that venous ultrasonography is accurate in the diagnosis of proximal vein thrombosis after TKA when the noninvasive vascular laboratory has experience with such studies.