[Five cases of the double renal pelvis and ureter]

Five cases of the double renal pelvis and ureter were encountered among 340 cadavers for dissection practice. Number of minor calices and their surface area in these kidneys were calculated, and causal relationship to abnormal organogenesis was discussed. These 5 cases were formal exclusively in consist of males; 4 right sides and 1 left side, 2 complete duplications and 3 partial duplications. The 5 cases were divided into 2 groups by the number and surface area of minor calices in upper and lower pelvises as follows: 1) The number and surface area of minor calices in the upper pelvis and the lower pelvis were respectively equivalent to the mean value of those in one normal kidney (case 1). 2) The sum of the number and surface area of minor calices in the upper and those in the lower pelvises were equivalent to the mean value of those in one normal kidney (case 2-5). These cases give useful criteria for classification of the double renal pelvis and ureter.