To determine if children with UPJO demonstrate a clinically significant change in somatic growth following pyeloplasty.

We retrospectively evaluated the growth chart data of infants with SFU grade 3 or 4 congenital hydronephrosis at our institution from 2015 to 2022. Of those, 35 patients underwent pyeloplasty and 66 had no surgical intervention. Patients met criteria if they had SFU 3 or 4 hydronephrosis and MAG3 renal scan. If patients underwent surgery, height and weight percentiles were recorded from the pre-op and 6–16-month follow-up visits. In non-surgery patients, measurements were taken near the median age of surgery in the intervention group and 6–16 months later. Interval changes in group height and weight percentiles are compared for significant changes.

The surgery and non-surgery groups did not differ in terms of gender (71% vs 74% Male), starting age (296 vs 244 days), starting weight (58th vs 52nd percentile), or time between measurements (255 vs 260 days), though the surgery group had significantly less height in the pre-operative period (43rd vs 55th percentile, p = 0.050) and were more likely to have delayed drainage on renal scan (83% w/delay vs 35%). The surgery group showed a significant increase in height (18.9 percentiles; 95% CI 11–27) and weight (6.0 percentiles; 95% CI 0.50–12) after intervention.

Patients with congenital hydronephrosis due to UPJO that underwent pyeloplasty showed a significant increase in weight and height at 6–16 months postoperatively compared to those that were managed with close observation. This suggests UPJO might lead to growth delay in infants.