CT findings in chronic post-thrombotic obstruction of the inferior vena cava

Four patients suffering from chronic post-thrombotic inferior vena caval obstruction were examined by CT scan. The CT appearance of the various venous collateral channels is presented. Other findings observed were bulky seminal vesicles and bilateral compressed bladder. Two unique findings for this entity were observed: 1) the disappearance of the long-since thrombosed IVC, or as we refer to it, the "lonely aorta" sign; and 2) absence of the posterior low-density area of the liver on the unenhanced cuts, representing the hepatic segment of the IVC. This noninvasive method facilitates differentiation among chronic post-thrombotic occlusion of the IVC, acute thrombosis, tumor thrombosis, and occlusion by tumor compression.