Congenital contralateral venous drainage of a right ectopic kidney to left common iliac vein: a rare case report

Arterial renovascular variation is common. However, specific reports of variations in renal venous drainage are limited. We report a case of a rare renovascular anatomical variant incidentally identified via abdominal computed tomography (CT). The right kidney was anteriorly rotated and low lying (iliac). The arterial supply entered the hilum of the kidney from two branches, specifically, from the abdominal aorta at L3/L4 and at the bifurcation of the aorta. Venous drainage was similarly variant with the superior pole draining into the inferior vena cava (IVC) at L3/L4. The inferior pole drained to the contralateral (left) common iliac vein coursing anteriorly to the right common iliac vein. To our knowledge, this particular venous variation has not been previously documented. This case is discussed in relation to renovascular embryology and clinical relevance for specialists operating within the retroperitoneum.