Objective: To identify crucial factors influencing surgical success, specifically focusing on the role of differential renal function (DRF), in children with ureteropelvic junction obstruction (UPJO) and glomerular filtration rates (GFR) at or below 15 ml/min.

Materials and Methods: Pyeloplasty results of 45 pediatric patients whose GFRs at or below 15 ml/min were analyzed retrospectively. Patients' demographic characteristics, anteroposterior diameters (APDs) of their renal pelvises, renal parenchymal thickness (PT), preoperative and postoperative DRFs and GFRs were recorded. The effects of the renal pelvis APD/PT ratio, the ratio between renal pelvis APD, and ultrasonographically measured preoperative length of the long axis of the kidney (LAK), and preoperative DRF values on the procedural success rates were evaluated.

Results: Twenty-nine patients met the inclusion criteria. The mean age of the patients was 48.79 (5-180) months. The mean preoperative GFR (13.44±1.52 ml/min) and DRF (28.69%±9.32) values increased up to 23.35±10.52 ml/min and 35.71%±15.04 at postoperative 6th- and 24.35±10.8 ml/min and up to 35.27%±14.57 at postoperative 12th-months, respectively (p<0.001, p<0.001). A preoperative DRF greater than 18 % was identified as a factor affecting procedural success of the surgery (p=0.006).

Conclusion: Contrary to what has been advocated in other studies, pyeloplasty should be preferred in patients with decreased renal functions having a GFR of 15 ml/min or lower, and DRF below cut-off value of 18 percent.

Keywords : pyeloplasty, ureteropelvic junction obstruction, poor renal function, differential renal function