Morphological observation of the horseshoe kidney with circumaortic venous ring

In a student course of gross anatomy dissection at Knagawa Dental College in 2010, we found an extremely rare case of the horseshoe kidney with circumaortic venous ring in a 43-year-old Japanese male cadaver. In this case, the kidney consisted of three parts: the original kidneys on both sides and an isthmus between them. The location of each kidney was lower than that of the normal kidney. The hili on both sides opened toward the ventral direction, and the ureters descended in front of the isthmus and entered the bladder normally. This horseshoe kidney had original left and right renal arteries that branched from the abdominal aorta. There were also two surplus arteries. There were three renal veins on the left side, and these renal veins formed the circumaortic venous ring. The anatomical and embryological significance of this anomaly and its associated vascular system are discussed. The anatomy and etiology of these anomalous structures are discussed with references in the literature.