Anatomical Study and Classification of the Precaval Right Renal Arteries with Implications for Retroperitoneal Surgery

Abstract Multiple renal vessels are a common finding. Few previous studies were focused on the precaval right renal artery (RRA). We explored 200 archived angioCT files of 105 males and 95 females. Four topographical types were defined: type 1, retrocaval; type 2, precaval (2a – hilar artery, 2b – inferior polar artery, 2c – entry in the inferior hilar angle); type 3, precaval, either anterior to a right renal vein (RRV) (3a) or posterior to a RRV (3b). In 24/200 cases (12%), 25 precaval RRAs were found. A case had a double precaval RRA. The precaval RRA left from the right common iliac artery in one case. In all the other cases, the precaval RRAs had aortic origins and were single and inferior to the main RRAs. In 23/24 cases, the vertebral level of the origin of the precaval RRAs varied from L2 to L5. A female case with precaval RRA had a thoracic RRA. In one case, we found two hilar retrocaval RRAs; the precaval RRA had a direct anastomosis with the superior one. The 2a/2b/2c/3a/3b types were found in 9/3/6/2/3 cases. The double precaval RRAs were types 2b and 2c. In a case, the right gonadal vein (RGV) was duplicated, and a venous arch joined the main RGV and a RRV to form a caval-renal-gonadal ring. The precaval RRA is not scarce. The precaval-to-retrocaval RRAs’ anastomosis is a previously unknown macroscopic collateralisation pathway. A thoracic RRA and a precaval RRA could be the only RRAs. The renal vasculature should be explored preoperatively on a case-by-case basis.