The normal arterial supply to the kidney and testis is through a single vessel arising from either side of the abdominal aorta at the level of L1-L2. The renal veins drain into the IVC and so does the right testicular vein; however, the left testicular vein enters the left renal vein. Due to the overlapping development of the urogenital systems, anatomical variations in the origin, course and distribution of the renal and gonadal arteries are not uncommon .
Embryologically, both the kidneys and gonads develop from the intermediate mesoderm which later differentiates into the urogenital ridge during the second month of intrauterine development. About 9–11 mesonephric arteries exist on either side of the embryonic abdominal aorta to supply the urogenital ridge. As the kidney ascends the caudal ones usually disappear. However, some persist as the phrenic, suprarenal, main and accessory renal and gonadal vessels. The lowest of the mesonephric artery usually becomes the testicular artery; the rest are obliterated, or one or two would persist as the accessory testicular artery. The mesonephric and the later formed metanephric arteries are interconnected towards the renal sinus; this plexus is responsible for the variability in the origin, side and numbers of the metanephric arteries .
Bergman’s compendium reports that accessory renal arteries are found in 25–30% of the individuals. In fact, these are the widely published variants of the lateral branches of the abdominal aorta in terms of their number, course and level of origin [1, 2]. The accessory renal arteries are noticed more on the left side (28%) and also frequently arise above main artery ; in contrast, the one identified in our specimen was below the main artery. The accessory renal arteries that enter the inferior aspect of the kidney (polar arteries) are often considered a potential risk to the ureteric compression, leading to hydronephrosis . However, in our finding, as the artery enters the renal sinus directly, it might not compress the ureter leading to a hydronephrosis. Additionally, the left accessory renal artery in this case is peculiar in that it does not fit into any of the five variation types described by Cases et al. .
The testicular arteries are reported to arise directly from the abdominal aorta only in less than 80% of the population (right- 76.3%, left- 78.9%). Other possible origins include a common trunk with middle suprarenal artery on the right side . Rarely, a triple or quadruple occurrence is also noted . Double testicular arteries (up to 17%) or those with retrocaval course (up to 13%) are reported as separate entities ; a double artery with retrocaval course in the same individual as identified in our specimen has not been reported earlier, to the best of authors knowledge. The retrocaval path of the gonadal artery can be traced back to the embryological position of the right splanchnic artery, which continues as the right testicular artery. Normally, the artery travels ventral to the supracardinal veins, but it assumes the retrocaval position when it crosses dorsal to the supracardinal anastomosis . Unlike earlier report that state that double testicular arteries with a retrocaval course frequently arch over the ipsilateral renal vein , our findings indicate that double testicular arteries with a retrocaval course do not exhibit this arching pattern.