Return to normal of 99mTc-plasmin test after deep venous thrombosis and its relationship to vessel wall fibrinolysis.

Fourteen patients with deep venous thrombosis (DVT) and a positive 99mTc-plasmin test were followed up to determine how soon a negative test was obtained. Localization and extension of the thrombi were determined by phlebography. Plasminogen activator activity in vein walls and local fibrinolytic activity after venous occlusion were measured in order to find out what the prerequisites for impaired thrombolysis are. The time required to obtain a negative 99mTc-plasmin test showed considerable variation, ranging from less than 1 week to more than 6 months. The 99mTc-plasmin test had returned to normal in 64% of the patients after 6 months. No relationship was found between vessel wall fibrinolysis and time to normalization. Instead, we found an association between the time to normalization of the 99mTc-plasmin test and the size of the thrombus, according to phlebography, as well as between the time to normalization of the 99mTc-plasmin test and the extension of leg points with a positive 99mTc-plasmin test at admission. The finding of abnormal 99mTc-plasmin test results more than 6 months after acute DVT is of practical importance and warrants caution when evaluating patients with symptoms and signs suggestive of acute recurrent DVT.