Asymptomatic deep venous thrombosis in the calf: accuracy and limitations of ultrasonography as a screening test after total knee arthroplasty.

Patients who have recently undergone total knee arthroplasty are at high risk of developing deep venous thrombosis (DVT) in the calf. The clinical diagnosis of DVT is difficult in these patients owing to recent operation. A combination of compression ultrasonography (US) and colour flow imaging was used as a screening method of asymptomatic DVT in 51 patients who had undergone total knee replacement surgery. Both limbs were examined by US from the common femoral vein to the ankle approximately 7 days after operation and the results were compared with bilateral venography. 12 patients (24%) developed infrapopliteal DVT on the operated side, in two cases the thrombosis extended to the lower part of popliteal vein. One patient had bilateral thrombosis. US showed sensitivity of 77%, specificity of 96% and overall accuracy of 93%. US seems to be a useful screening method for DVT after knee replacement operation.