Fig. 2

Schematic sketch of venous system. Picture A shows that the normal IVC is formed by the joining of the left and right common iliac veins and pours into right atrium. Picture B demonstrates the interruption of IVC from infra-hepatic to supra-renal segment. Different from previous cases whose IVC continue as azygos vein, our patient did not have the continuation. Her LRV received a large part venous blood from the infrarenal IVC and the right kidney, through an expanded communicating branch, draining into the hemiazygos. A small portion of infrarenal IVC blood flowed reversely into the bilateral lumbar veins, via right and left ascending lumbar veins, draining into the azygos vein(right) and hemiazygos vein(left) separately. This bypass explains the expanded LRV, azygos and hemiazygos vein, and bilateral lumbar veins