Peri-hilar branching patterns and morphologies of the renal artery: a review and anatomical study.

The peri-hilar (extra-parenchymal) branching pattern of the renal artery is important for surgeons to know prior to kidney transplantation. The aim of this study was to identify the variations in peri-hilar branching pattern and morphology of the main renal artery. Arteriograms of 81 kidneys were examined. After marking the renal shadow, the main renal artery was traced laterally from its origin. Morphologically, the arterial branching patterns were classified into ladder (with sequential branching points) and fork (with a common branching point) types. The latter was either duplicated or triplicated. The peri-hilar morphology of the main renal artery was then categorized according to its primary and secondary divisions and their patterns. If a single category encompassed at least 5% of the observed figures, it was recorded as a "cardinal" peri-hilar arterial morphology. Otherwise, it was counted within the category of "infrequent" morphologies. At the level of the main artery, a fork pattern was observed in 92.6% (n = 75) (80.2% duplicated (n = 65) and 12.4% triplicated (n = 10)) and a ladder pattern in 7.4% (n = 6) of kidneys. Of 160 primary branches off the fork-type main artery, a secondary division was found in 68.8%. Only one further division (4.4%) was noted from the ladder-type primary arteries. Eight "cardinal" peri-hilar renal arterial morphologies were identified and represented 82.7% of all cases. At least ten "infrequent" morphologies were also found. These patterns showed some alteration with the presence of a supernumerary renal artery. We concluded that the peri-hilar branching of main renal artery is highly variable, though this may follow certain patterns. We believe that the results may be useful to surgeons operating at the renal hilum especially during kidney transplantation.