Anomalies of the Renal Artery. In about two thirds of individuals, a single renal artery passes to each kidney. In the remainder, a variety of anomalies may be seen.

Roughly 1 in 10 kidneys, for example, receives additional branches from the aorta that enter at the hilum, known as accessory or supernumerary renal arteries. Accessory arteries are not duplicated vessels, but rather one or more segmental (end) arteries uniquely responsible for a portion of the kidney. Accessory arteries are regarded as persistent embryonic lateral splanchnic arteries. They may arise from the aorta as high as the diaphragm or as low as the internal iliac artery; however, they most frequently arise caudal to the main artery. Most occur on the left side. Right accessory arteries arising caudal to the main artery usually pass anterior to the inferior vena cava (IVC).