The renal segment of the IVC is formed by the confluence of these two systems, that is, suprasubcardinal and postsubcardinal anastomoses, named renal collar, which is followed by the atrophy of the posterior cardinal veins.
With reference to the embryology, a retroaortic renal vein is found when the ventral arch of the renal collar goes into atrophy leaving the dorsal side of the arch patent.
This circumaortic venous collar or, the renal collar (Fig-3, 4) is formed by
The persistence of 'renal collar' gives rise to double left renal veins, preaortic and post aortic both draining into the IVC(6).
The term 'renal collar' in embryo was designated by Huntingdon and McClure in 1920 (8).
Davis and Lundbery reported in 270 autopsies a retroaortic left renal vein in 1.8% and circumaortic renal collar in 1.5% (11)
et al in 2008, reported a very low incidence of renal collar, i.e.
In 2010, Sangeetha K et al observed a male case having a circumaortic renal collar in a study of 20 cadavers (18).
In the present study, we have encountered only one male case with a persistent renal collar out of 30 cadavers, accounting to incidence of 3.33% .
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).