renal collar

re·nal col·lar

in the embryo, a ring of veins around the aorta below the origin of the superior mesenteric artery.
References in periodicals archive ?
Associated conditions of relevance to the abdominal procurement surgeon include anomalies of the renal veins (circum aortic renal collar, and retro aortic renal vein) (1), right retro caval ureter (3), horseshoe kidney, congenital right renal agenesis (4) and cloacal exstrophy (5).