“…This is con- firmed by recent analysis of Zhu et al [20], who observed right renal vein variations in 19.2%, and left renal vein variations in 7.1% of their population, with supernumerary veins on the left found in 2.7% and 18.7% on the right side. Similarly, Janschek et al [7] report more common variations on the right side (23%) than on the left (6.7%). Ozkan et al [11] have observed single left renal artery in 86% of their 855 angiography patients, and single right one in 83% of patients, which is more frequent than in our group.…”