Comprehensive Study of Arrangement of Renal Hilar Structures and Branching Pattern of Segmental Renal Arteries: An Anatomical Study.

Background The knowledge of renal artery (RA) and its segmentation is critical before attempting any surgical procedure of kidney. The RA receives blood supply from various arteries during its descent in the embryonic period. As a result, the segmental RAs show a lot of variability in the site and pattern of origin as well as its point of entry in the kidney. Aim/objective The aim is to study the variable pattern existing in different segmental RAs and the arrangement of structures at the renal hilum. Methods The RA of 205 kidneys (68 paired and 69 unpaired) was studied and the segmental pattern was exclusively observed in cadavers by dissecting 161 kidneys, making resin/silicon casts of 34 kidneys and radiological imaging of 10 kidneys. Results The results obtained were quite significant and provided in detail understanding of the five main segmental arteries and the arrangement of structures at the renal hilum. Great variations were seen in the disposition of structures at the renal hilum. Six different patterns of structures at the renal hilum were obtained. Pattern 1 was the commonest pattern with an incidence of 30.3% followed by pattern 2. The site of origin of segmental arteries and their point of entry into the kidney were recorded and tabulated. The segmental arteries were classified into different types based on the frequency of their occurrence in decreasing order. In each of them, Type 1 is the commonest variant seen based on the origin of the apical artery (A), anterior upper segmental artery (AU), anterior middle segmental artery (AM), lower segmental artery (L), and posterior segmental artery (P). Conclusions The arrangement of hilar structures has been classified into six patterns and the variations existing in each of the segmental branches of the RA have been categorized as well. The knowledge will be invaluable for accurate radiographic interpretation of the renal vasculature and effective surgical planning in cases involving kidney transplantation, renal trauma, and partial nephrectomy. Furthermore, it will serve to prevent complications during surgical procedures.