Introduction

Renal arteries mostly arise from the abdominal aorta at the level of the L1–L2 vertebral body or intervertebral disc. However, variant renal arteries have been reported in 30% of the entire population [1, 2].

The incidence rate of variant renal artery reflects the mechanism by which the renal blood supply changes during the embryonic stage and early fetal life. As the kidneys migrate cranially from the pelvis, they receive new branches from the superior aspect of the aorta. The preceding caudal vessels usually regress and disappear, but failure to regress leads to variant renal arteries [3]. It is important to recognize the anatomic variation in advanced when performing surgery or interventional procedures on the kidney.

We report a rare case of anatomical variants in renal arteries with an ectopic kidney, incidentally detected on multidetector computed tomographic (MDCT) angiography for pre-operative evaluation of a skin defect in the left leg.

These anatomic variations include the main renal artery originated from a contralateral common iliac artery (CIA) and the other accessory arteries arose from the abdominal aorta, level T12/L1 and L4. The accessory renal arteries arising from the contralateral CIA are very rare. It was reported only several cases by Halloul et al., Hounton et al., and Erdogan et al. [4,5,6].

Case Presentation

A 60-year-old male with unremarkable medical history was transferred to the Department of Plastic Surgery for the management of a posttraumatic wound in the left lower leg. He was involved in a traffic accident about 45 years ago. The patient was consulted for skin ulceration management and pain control.

During the preoperative evaluation, MDCT angiography revealed several anatomical variants of the right kidney. There were four right renal arteries. The main renal artery originated from the left proximal CIA and supplied the middle pole of the right kidney. The other renal artery originated from the aortic bifurcation and supplied the lower pole of the right kidney. The other two renal arteries, branching from the abdominal aorta, lower thoracic level T12, and lower lumbar level L4, supplied the upper pole of the right kidney (Fig. 1).

Fig. 1
figure 1

The main renal artery (thick arrow) originates from the left proximal CIA, another renal artery (arrowhead) originates from the aortic bifurcation and the other two renal arteries (arrow) branch from the abdominal aorta, lower thoracic level T12 and lower lumbar level L4. RK Right kidney

Full size image

The normal size of the adult kidney is about 10–14 cm long in size and is shaped like a bean. In addition, the renal hilum lies vertically at the anteromedial aspect of the kidney. However, the size of this kidney was 8 cm long in size, small and spherical in shape. The renal hilum faces anteriorly due to incomplete rotation. The ureter was located laterally above the normal position without functional abnormality.

He underwent elective surgery for debridement and a split-thickness skin grafting for the skin defects of the left leg. He was discharged on postoperative day 1. The pain and skin defects improved without complications.

Discussion

Vascular variants of renal arteries have been commonly reported. Although the incidence varies geographically, it has reportedly reached up to 30%. The main right renal artery typically originates from the abdominal aorta between the upper margin of L1 and the lower margin of the L2 vertebra, below the superior mesenteric artery [7].

The development of the kidney and its vessels is complex, and the development of kidney arterioles remains poorly understood. Renal artery variants are vestigial structures caused by failure to degenerate during the ascent of metanephros. Embryologically in the 18 mm fetus, the developing mesonephros, metanephros, suprarenal glands, and gonads are supplied by nine pairs of lateral mesonephric arteries, arising from the dorsal aorta [3]. Felix divides these nine pairs of arteries into three groups: cranial (1st and 2nd pair), middle (3rd–5th pair), and caudal (6th–9th pair) [7]. The renal arteries develop from a single pair in the middle group. The remaining arteries of the middle group give rise to accessory or aberrant renal arteries [6].

The abnormalities in the renal arteries are related to the various developmental positions of the kidneys. During early development, the kidneys locate in the sacral region of the embryo. As the disproportionate growth of the body, the final position of the kidneys is in the lumbar region. As the location of the kidneys changes, their arterial supply also shifts from the common iliac artery to the abdominal aorta. The kidneys receive vascular supply from branches of the dorsal aorta called renal arteries [3, 8, 9].

Accessory renal arteries are also very common which mostly originate from the abdominal aorta. In some reports, the accessory arteries originated from the CIA, superior mesenteric arteries or inferior mesenteric arteries [3,4,5, 10].

In rare cases, such as the present case, the main renal artery originated from the contralateral CIA. In most of these cases, the kidneys were located in the pelvis. In the present case, the kidney was located at the level of L2–L5, and the accessory renal artery originated from the aortic bifurcation, supplying the lower pole of the kidney.

It is clinically important to understand the anatomic variation of the renal arteries for the management of the following processes; kidney transplant surgery, abdominal aortic aneurysm treatment, abnormal renal artery treatment, renal vascular hypertension evaluation, and radiological interventions.

Conclusion

This case documented a rare anatomic variant, involving multiple accessory renal arteries, including the main renal artery originating from the contralateral iliac artery, caused by specific renal embryological conditions. These variants should be analyzed to effectively perform surgical and interventional procedures.