A CANDIDATE KIDNEY DONOR WITH ANATOMIC VARIATIONS IN RENAL ARTERIES

A 53 year old man was admitted to the hospital for a preoperative assessment as a candidate donor of a renal graft. His medical history included coronary artery disease, which was treated with balloon angioplasty and the placement of an intraluminal coronary artery stent in the left anterior descending artery 1 year before his admission. Digital subtraction angiography (DSA) of the renal arteries manifested the presence of four renal arteries in the left kidney (Fig. 1) and the coexistence of a main and a polar artery in the right kidney. The right polar artery supplied a segment of the lower pole of the right kidney and stemmed from a common branch with the ipsilateral inferior phrenic artery. The high frequency of polar arteries, multiple arteries and the origin of renal arteries from the aorta at different heights or from other arteries can be explained by the embryological development of the kidney. The occurrence of four renal arteries is of a rare incidence (<1%) while a lower polar artery correlates with an increased rate of recipient ureteral complications. Polar arteries and multiple renal arteries are important in kidney transplantation. Multiple renal arteries (MRA) are the most frequently encountered anatomical variation in kidneys. In one report the incidence of unilateral MRA was 23%, and that of bilateral MRA was 10%. Keller JE et al. reviewed a total of 230 laparoscopic donor nephrectomies performed at a single institution. Multiple arteries were present in 37 donors. No significant difference in estimated blood loss, transfusions, operative time or length of hospital stay was noted between multiple and single laparoscopic donor nephrectomies. Benedetti et al. reported the same results among 163 patients with MRA versus 835 with single renal arteries. Available studies support that donor morbidity and recipient intraoperative, early and late postoperative outcomes do not differ between donors with multiple renal arteries and those with a single renal artery. The gold standard technique for preoperative donor evaluation is a DSA as it provides a precise evaluation of supernumerary and accessory renal vessels. However, the procedure is invasive, uses ionizing radiation and large amounts of nephrotoxic opaque material. Additionally, selective catheter placement in the renal arteries comprises an increased risk for intimal injury, dissection and subsequent stenosis of the vessel. Magnetic resonance angiography (MRA) is an acceptable alternative non-invasive imaging modality in donors because it has the added benefits of no iodinated contrast material and no exposure to ionizing radiation. MRA is inadequate in detecting supernumerary vessels, accessory renal arteries and the presence of smalldiameter vessels and it cannot be recommended as the sole diagnostic tool in unclear cases. Multidetector row computerized tomography angiography is non-invasive and it can provide sufficient information about renal and extrarenal anatomy. Multidetector row computerized tomography angiography visualizes renal veins with high accuracy and its spatial resolution is superior to that of MRA. Radiation exposure of healthy kidney donors must be considered when using CT angiography, although, the total radiation dose for a triple-phase CT was shown to be less than that with the DSA. There has been some controversial discussion regarding the best approach to follow. Selection of a procedure should be guided by the experience of the radiologist, the Fig. 1 Digital subtraction angiography depicting the vasculature of the left kidney with the four renal arteries stemmed from different branches of the descending aorta. Correspondence