Purpose: Although color Doppler flow imaging (CDFI) has been shown to accurately depict calf vein thrombosis in symptomatic patients, this technique has not been proved accurate for detection of calf vein thrombosis in a population restricted to asymptomatic postoperative patients.
Patients and methods: To evaluate the accuracy of CDFI in asymptomatic postoperative patients, both CDFI and contrast venography were performed on 78 limbs of 76 patients without symptoms of deep venous thrombosis (DVT) who had undergone either hip or knee replacement. CDFI and venographic examination were interpreted blindly with respect to the results of the other modality or clinical findings. Venography was the standard for comparison of results.
Results: Fifty-six percent of CDFI examinations of the calf vein were technically adequate. The remaining studies were compromised technically by limb swelling and/or obesity. For the technically adequate CDFI studies, calf vein thrombosis was detected in eight of 10 patients. Calculated sensitivity in this cohort was 80%, and specificity was 97%. The sensitivity of CDFI for acute calf DVT in all patients, regardless of image quality, was 42%.
Conclusion: These observations suggest that state-of-the-art CDFI is not an accurate examination for acute calf vein DVT in asymptomatic postoperative patients. CDFI is associated with a high rate of technically compromised studies and relatively low sensitivity in studies that are deemed technically satisfactory. These observations do not preclude the use of CDFI in postoperative patients for detection of thrombus extension into the popliteal vein or for detecting thrombosis of more proximal lower extremity veins.