Right Renal Vein Fenestration: A Novel Anatomical Variant.

In the typical anatomy, two renal arteries, left (LRA) and right (RRA), enter the renal hilum, and two renal veins, left (LRV) and right (RRV), end in the inferior vena cava. Finding multiple bilateral renal arteries and veins is uncommon. The fenestration of the RRV has not been previously reported. We report it here in a variational context that includes multiple renal vessels and precaval RRAs. The anatomic variant reported here was identified during the evaluation of a 66-year-old male's CT angiogram. On each side, triple renal arteries were found, consisting of one main artery, superiorly, and two accessory arteries, middle and inferior. The main RRA was retrocaval, but the other two RRAs were precaval. All the renal arteries entered the renal hilum. A right inferior polar branch arose from the middle RRA. The RRV was doubled. The caval end of the inferior RRV was fenestrated. The anterior arm of this fenestration received the right gonadal vein. A circumaortic LRV was found. Its preaortic main arm was joined by the retroaortic one, which, in turn, drained the satellite veins of the middle LRA and inferior LRA. Various anatomical variants of the renal vessels may be found bilaterally and concomitantly. These should be carefully documented when surgical and endovascular interventions are planned. Knowledge of any possible morphological variations, whether frequent or extremely rare, is crucial.