Influence of Iliac Vein Compression on Subsequent Recanalization after Deep Venous Thrombosis

Compression of the left common iliac vein by the right common iliac artery is a frequent cause of left-sided deep venous thrombosis, and would lead to poor subsequent recanalization. However, this finding has been difficult to confirm. In this study, we investigated the impact of iliac vein compression on subsequent recanalization by using ultrasonography, computed tomography (CT), and magnetic resonance venography. Twenty-nine patients with left iliac vein thrombosis were studied. The diameter of the left common iliac vein at the site of maximal compression was measured by CT in each patient, and the reduction in diameter of 50% or more was defined as having compression. At the follow-up examination, the individual venous segment was classified into three levels according to the degree of recanalization: totally occluded, partially occluded, and totally recanalized. Twenty-one of 29 patients were judged to have compression. The incidence of iliac compression was significantly higher in women than in men (16/18 vs 5/11). At 1-year follow-up, recanalization of iliac segment in patients with compression was significantly poorer than that without compression. Iliac compression is strongly associated with persistent occlusion of iliac segment.