Preaortic iliac venous confluence ("marsupial cava"): a rare anomaly of the inferior vena cava.

A patient was shown by computed tomography (CT) to have a rare developmental anomaly of the inferior vena cava (IVC), in which the iliac venous confluence is located anterior (rather than posterior) to the right common iliac artery. Recognition of the anomaly is important prior to surgical intervention in that area, as well as to prevent misinterpretation of the anomaly as representing adenopathy.