RENAL HISTOLOGICAL-CHANGES SECONDARY TO URETEROPELVIC JUNCTION OBSTRUCTION

The treatment of children with apparent ureteropelvic junction obstruc tion is controversial. In an asymptomatic infant or child the decision to recommend pyeloplasty usually is based on interpretation of the re nal scan. We retrospectively analyzed the renal biopsy obtained during pyeloplasty in 55 children. Histological changes were compared to the differential renal function revealed on the preoperative renal scan. Histological changes were graded on a scale of I to V: I-normal, II-mi ld dilatation of the collecting tubules or Bowman's space and III to V -progressively severe changes of obstructive uropathy, including reduc ed glomerular number, glomerular hyalinization, cortical cysts and int erstitial inflammation. Patient age ranged from 4 days to 19 years (me an 4.8 years). Mean differential function according to histological gr ade was I-49%, II-43%, III-42%, IV-30% and V-25%. Of 33 patients with a differential function of 40% or greater 26 (79%) had a grade I or II biopsy, while 21% had a more significant alteration in renal histolog y. In contrast, when the differential function was less than 40% 6 of 18 patients (33%) had grade I or If disease on biopsy. In conclusion, in approximately 25% of children with ureteropelvic junction obstructi on there is a disparity between preoperative differential renal functi on computed during diuretic renography and renal biopsy.