Double right inferior vena cava associated with an anomalous venous ring encircling the right common iliac artery: Report of one case with CT and US

Embryogenesis of the inferior vena cava (IVC) is a complicated process involving development, regression, anastomosis, and replacement of three pairs of venous channels: posterior cardinal, subcardinal, and supracardinal veins. Congenital anomalies of the IVC are explained by abnormal persistence or regression of parts of these embryonic veins. We describe a case a case of right double IVC associated with an anomalous venous ring encircling the right common iliac artery evaluated with CT and US. At the level of the aortic bifurcation, the dorsal vessel was seen posteriorly to the common iliac artery, and continued as the right common iliac vein. The ventral vein is divided in two branches: the left one continued as the left common iliac vein; the right one passed anteriorly to the right iliac artery, encircled it, and communicates into the right common iliac vein. The two vessels fused together below the level of the renal veins. The presence of a double right IVC is rare. It is usually asymptomatic, and requires no treatment. Preoperative awareness of the presence of this condition is important to prevent serious complications during abdominal and retroperitoneal surgery or during IVC filter placement. The main differential diagnoses for right double IVC include other venous anomalies such as periureteral venous ring, retroperitoneal lymphadenopathy, and the presence of other pathologic conditions (IVC thrombosis, dilated retroperitoneal vessels in portal hypertension and retroperitoneal hypervascular tumors).