The purpose of this study is to assess the clinical significance of supranormal differential renal function (DRF) in the recovery of unilateral hydronephrosis (HN) after surgery, pediatric patients who underwent pyeloplasty for ureteropelvic junction obstruction (UPJO) who showed supranormal DRF (> 55%) in the DTPA renography will be analyzed.

To assess the clinical significance of supranormal differential renal function (DRF) in the recovery of unilateral hydronephrosis (HN) after surgery, pediatric patients who underwent pyeloplasty for ureteropelvic junction obstruction (UPJO) who showed supranormal DRF (> 55%) in the DTPA renography will be analyzed. Clinical parameters including age at the first visit, age at operation, gender, laterality, and follow-up period will be evaluated. To evaluate predictors of recovery from supranormal renal function according to the level of DRF, univariate and multivariate logistic regression analyses will be performed. Patients would be subcategorized into two groups; group A (DRF ≤60%) and group B (DRF >60%) in consideration of the mean value of preoperative DRF and each parameter of group A was compared to that of group B using independent sample's t test and chi square test. Kaplan-Meier analysis and log-rank test will be used to determine the difference of recovery time of obstructed hydronephrosis in each parameter.

Inclusion Criteria:

• ureteropelvic junction obstruction
• hydronephrosis
• differential renal function more than 55% in DTPA
• follow-up period more than 1 year

Exclusion Criteria:

• urological anomalies, such as vesicoureteral reflux, ureterocele, cystic kidney disease, posterior urethral valves, duplex anomalies, neurogenic bladder, and solitary kidney or patients who underwent any previous urological surgery

patients with unilateral UPJO pediatric patients who underwent dismembered pyeloplasty and preoperative HN in USG and supranormal renal function in DTPA renography