[Inferior vena cava malformations and deep venous thrombosis].

We carried out a prospective study of 116 patients under 50 years of age who had deep venous thrombosis of the lower extremities to determine whether the presence of congenital anomaly of the inferior vena cava (IVC) was a risk factor for the disease. All patients were investigated by Doppler echography. Some 37 patients who had iliac vein occlusion also underwent phlebography. In 10 patients in whom the IVC was difficult to image, magnetic resonance angiography or computerized axial tomography was carried out. In all patients, studies of antithrombin, protein C and protein S deficiency, factor V Leiden, prothrombin G20210A, antiphospholipid antibodies, and acquired risk factors were also performed. Of the 37 patients who had iliac vein occlusion, six had an IVC anomaly. Two of these patients had antiphospholipid antibodies, while another had prothrombin G20210A. Two patients with an anomaly had recurrent thrombotic occlusion. In conclusion, congenital IVC anomalies were present in 16.2% (95% confidence interval, 6.2-32%) of young patients with iliac thrombosis.