Introduction: The aim of this study was to evaluate the safety and efficacy of flexible ureteroscopy using a tip-flexible pressure-controlling ureteral access sheath (TFPC-UAS) for renal stones in children. Methods: Consecutive patients aged 5–18 years with renal stones of diameter 1–3 cm were enrolled between January 2022 and November 2023 at Ganzhou People’s Hospital. The patients were treated with flexible ureteroscopy using the TFPC-UAS. The renal pelvic pressure (RPP) parameters were set as follows: control value at −10 mm Hg to 5 mm Hg, warning value at 20 mm Hg, and limit value at 30 mm Hg. The infusion flow rate was set to 100–120 mL/min. A holmium laser (276 μm) was used to fragment the stone at 2.0–2.5 J/pulse with a frequency of 20–30 pulses/s. The cases were analyzed for RPP, operative time, stone-free rate, and complications. Results: A total of 21 consecutive patients were included. Two patients were switched to percutaneous nephrolithotomy owing to sheath placement failure. The RPP was −4.6 ± 2.1 mm Hg. The mean operative time was 56.5 ± 17.1 min. The postoperative hospitalization time was 1.5 ± 0.3 days. The stone-free rates at 1 day and 1 month after surgery were 81.0% and 85.7%, respectively. Residual stones in 2 patients were cleared after extracorporeal shockwave lithotripsy. Three cases of Clavien I complications and one case of Clavien II complications occurred. No major complications (Clavien grade III–V) were observed. Conclusions: Flexible ureteroscopy with a TFPC-UAS is safe and effective for renal stones in children.

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