The prevalence of the fenestrated left renal vein

The left renal vein (LRV) is typically a single preaortic vein. The discovery of fenestrated LRVs (FLRVs), a rare occurrence previously reported only twice, has piqued our interest. We aimed to determine the prevalence of such variants using an angioCT batch.

We meticulously studied archived angioCT files of 95 men and 55 women. The morphology of the LRVs was carefully checked on planar sections and by three-dimensional volume renderings, ensuring the accuracy of our findings.

In 3.34% of cases, four males and one female were found FLRVs. Their posterior projections on the aorta were variable. The FLRVs were either partly preaortic, immediately to the left side of the aorta, or at a distance to the left side of the aorta. There were three true FLRVs, with a single vein attached at the lateral end and two pseudo-fenestrations, with two veins attached laterally. The left suprarenal and gonadal veins drained, respectively, in the superior and inferior arms of the fenestrations. In 2/5 cases, the second left lumbar vein drained into the inferior arms of the fenestrations. In one case, the FLRV was traversed by the inferior segmental branch of the renal artery.

Our findings have significant implications for surgical procedures targeting the left renal pedicle. The FLRV, with its morphological and topographical variability, should be considered among the anatomical variations of the LRV that may impede or endanger such procedures. However, it can be accurately discriminated on angioCT scans, providing a potential solution to this challenge.