99mTc plasmin in 394 consecutive patients with suspected deep venous thrombosis

Three hundred and ninety four consecutive out-patients with suspected deep venous thrombosis (DVT) were investigated with the 99mTc-plasmin test and physical examination and 307 of them with phlebography. Fresh thrombi were present in 124 patients and the plasmin test was pathological in 118 of these (sensitivity 95%). The thrombi that were missed were all located below the knee and measured less than 10 cm on the phlebographic films. The predictive values of negative and positive tests were 91% and 49%, respectively. The predictive value of a positive test was higher with an increasing number of measuring points with a pathological uptake. To get the final result, a single series of measurements 5 min after injection was sufficient. If clinical signs of inflammation were present. the plasmin test was usually pathological. Median time for the plasmin test to become normal during anticoagulant therapy was 14 days for calf DVT and 6 months for proximal DVT. The plasmin test was found to be useful as a screening test in patients without extensive signs of inflammation in the legs. It has a high sensitivity even in patients with long-standing symptoms.