Proximal extent of pelvic vein thrombosis and its association with pulmonary embolism

Objective: Conventional methods such as duplex ultrasound scanning do not provide accurate information about proximal extension of pelvic vein thrombosis. We evaluated proximal extent of thrombus toward pelvic veins with magnetic resonance imaging in patients with suspected deep vein thrombosis (DVT) proximal to the inguinal ligament on the basis of duplex ultrasound scans. In addition, frequency of pulmonary embolism (PE) and early (4 weeks) clinical outcome were evaluated. Methods. Two hundred twelve patients with acute symptomatic DVT proximal to the inguinal ligament, diagnosed at duplex ultrasound scanning, were enrolled in this prospective study. All patients underwent magnetic resonance imaging of the abdominal and pelvic veins, as well as lung scintigraphy to detect the presence of pumonary embolism. Results. In 24 of 212 patients (11%), thrombus was restricted to the femoral vein. The thrombus extended into iliac veins in 142 patients (67%) and into the inferior vena cava. in 46 patients (22%). The frequency of PE was not associated with the most proximal extension of thrombus (P = .61). No patients died as a consequence of thromboembolic events. Conclusions. Extension of DVT into the inferior vena cava occurs relatively frequently. In our patients this finding was not associated with higher risk for PE compared with DVT of the femoral or iliac veins.