Evaluating the Impact of Robot-Assisted Laparoscopic Pyeloplasty (RALP) on Pediatric Hydronephrosis with and Without Abdominal Pain Symptoms: A Cohort Study Using Inverse Probability of Treatment Weighting (IPTW).

Objective: This study aimed to evaluate the effectiveness of robot-assisted laparoscopic pyeloplasty (RALP) in pediatric hydronephrosis with or without abdominal pain symptoms, and to compare post-operative outcomes between these two clinical subtypes. Methods: We retrospectively reviewed pediatric patients who underwent RALP at our institution between April 2020 and October 2024. Patients were categorized into hydronephrosis with and without abdominal pain groups. The primary endpoints were renal pelvis anteroposterior diameter (APD) and percent improvement in APD (PI-APD). Inverse probability of treatment weighting (IPTW) was applied to minimize selection bias and balance baseline covariates. Results: A total of 273 pediatric patients were analyzed, including 104 cases with abdominal pain and 169 without. After IPTW adjustment, the baseline characteristics of the groups were comparable. At 6 months post-operative, the abdominal pain group showed slower reduction in APD (1.3 cm vs. 1.2 cm, p < 0.05) and PI-APD (37% vs. 50%, p < 0.05). No significant differences were observed at the 12-month or last follow-up. The overall surgical success rate was 97.1% (265/273). The IPTW-adjusted analysis revealed a higher surgical success rate in the abdominal pain group (99.9% vs. 97.1%, p < 0.05). Conclusions: RALP is safe and effective for pediatric hydronephrosis, regardless of the presence of abdominal pain. Although both groups showed comparable recovery at 12 months or last follow-up, the patients with abdominal pain exhibited slower improvement at 6 months, suggesting potential differences in early post-operative remodeling between these subtypes.