Late changes in veins after deep venous thrombosis: ultrasonographic findings

In a prospective trial, 43 patients (45 legs) were re-examined by high resolution and continuous-wave Doppler ultrasonography 3-32 months after an acute episode of deep venous thrombosis (DVT). The veins were abnormal in 31 legs (69%). Abnormal veins were either narrowed with a highly echogenic lumen (thought to represent persistent occlusion) or with a relatively sonolucent lumen and thickened walls (thought to represent recanalized veins). Collateral veins were present. Some compression by probe could be achieved in partially occluded veins, but full collapsibility was absent. Continuous-wave Doppler studies were similar to those in acute DVT. In order to be able to diagnose new episodes of DVT in patients who have had DVT in the past, a baseline ultrasound study should be carried out approximately 6-12 months after an acute episode. In the absence of such a baseline study, contrast phlebography should be resorted to.