Long-term renal outcomes after pediatric pyeloplasty: Defining optimal imaging intervals and predictors of functional...

This study evaluates long-term outcomes after pyeloplasty for unilateral ureteropelvic junction obstruction (UPJO), examines the correlation between early postoperative imaging and outcomes, and identifies predictors of functional recovery.

This retrospective study analyzed 116 pediatric patients who underwent open dismembered pyeloplasty for unilateral UPJO from 2010 to 2023, with a minimum of three years postoperative follow-up. Patients were classified as "recovered" if their differential renal function (DRF) improved by over 5 % on the final renogram. We examined various parameters, including the ipsilateral-to-contralateral renal parenchymal thickness ratio (ParT ratio), anteroposterior pelvic diameter (APD), percent regression in APD (APDred%), and APD/parenchymal thickness ratio (APD/PT) at baseline and monthly postoperative ultrasounds. Nonparametric tests were used for group comparisons, and multivariable logistic regression identified independent predictors of recovery. We also evaluated early postoperative measurements (3 and 6 months for ultrasound; 12 months for renography) against final values to determine correlations with long-term outcomes.

The median age at surgery was 24 months (IQR 6-96), with a median follow-up of 96 months (IQR 60-120). Among patients with a ≥5 % increase in long-term differential renal function (n = 26), baseline renal function was lower (33.7 % vs. 41.5 %; p = 0.002) than in those who did not improve. The improved group also had a lower ParT ratio at baseline and six months (0.43 vs. 0.51; p = 0.046). A higher percentage of the improved group had surgery before one year of age (58 % vs. 33 %; p = 0.038). Logistic regression identified age under one year and lower baseline renal function as predictors of recovery. At one year postoperatively, renal function remained stable in 115 out of 116 patients (99 %) according to subsequent renograms. Six-month ultrasound results closely aligned with final pelvic diameter regression, whereas other measures did not significantly correlate with improvement. There were no significant differences in antenatal hydronephrosis, SFU grades, or rates of febrile urinary tract infections between the groups.

In pediatric UPJO, age at surgery <1 year and lower baseline DRF are associated with postoperative functional improvement. Six-month ultrasound measurements of AP diameter reduction accurately reflect pelvic outcome at long-term follow-up, while the one-year renogram provides an appropriate assessment of long-term renal function.