Clinical implications of the convex supradiaphragmatic inferior vena cava

The configuration of the supradiaphragmatic segment of the inferior vena cava (SIVC) was evaluated on lateral chest radiographs to determine the clinical situations in which a posterior convex contour occurred. Of 34 patients with a convex SIVC, 31 had cardiovascular abnormalities. Left ventricular enlargement was present in 17 of 34 (50%), and right ventricular failure in 13 (38%). Valvular regurgitation, left-to-right shunts, narrow anteroposterior chest diameter, and chronic obstructive lung disease were also present. In 102 consecutive normal patients, the SIVC was visible in 97%; only 1 patient had a convex SIVC (p = 10(-7)). The results show that detection of a convex SIVC suggests associated abnormalities.