Extreme Variability of the Kidney Hilar Architecture: A Radioanatomical Map to Guide Surgical Approaches.

Background: Retroperitoneal surgical corridors, particularly in robotic-assisted partial nephrectomy and donor surgery, require precise knowledge of hilar vascular orientation. The typically described Vein-Artery-Pelvis (VAP) anatomy is often assumed, yet its reliability is poorly quantified. Therefore, the purpose of the present study is to provide a comprehensive radioanatomical map of hilar architecture to enhance surgical safety and predictability. Methods: Contrast-enhanced computed tomography (CT) scans of the abdomen from 200 patients (104 males and 96 females) were evaluated. The anterior-to-posterior sequence of hilar structures, the frequency of early vascular branching, and the presence of accessory vessels were documented and stratified by sex and laterality. Results: The conventional VAP sequence was observed in a minority of cases, occurring in only 32.6% (131 sides). The map identified 37 distinct sequence variants. The most common variants included VAPA (9.0%), AVAP (7.8%), and VAAP (7.0%). Adherence to typical VAP anatomy was significantly lower in males (27.9%) than in females (37.7%). Arterial complexity, characterized by early branching or accessory vessels, was present in 43.2% of sides, with a significantly higher occurrence in males and on the right side. Venous mapping revealed a marked lateral disparity; accessory veins were predominantly right-sided (12.5%), whereas early venous branching was predominantly a left-sided feature (30.0%). Conclusions: Renal hilar architecture demonstrates substantial variability, with the classical VAP configuration representing a minority arrangement. These findings highlight the importance of individualized preoperative imaging assessment and may help anticipate anatomical complexity in retroperitoneal surgery.