Retrograde intrarenal surgery using a flexible ureterorenoscope in children with urolithiasis

BACKGROUND: Extracorporeal shock wave lithotripsy remains the first-line therapy in children with renal stones up to 2 cm. Recently, retrograde intrarenal surgery has become an alternative technology for fragmenting stones located in the renal pelvis and calyces. AIM: The work aimed to perform a retrospective analysis of the outcomes and complications of flexible ureterorenoscopy in children with urolithiasis. METHODS: The study included 63 children (65 renal units) who underwent retrograde intrarenal surgery. A total of 70 procedures were performed, including nephrolithotripsy in 59 cases (84.3%) and flexible ureterolithotripsy in 4 cases (5.7%). Nephrolithoextraction and ureterolithoextraction with a flexible endoscope were also performed. Stone size, volume, and density were assessed. The statistical association between the stone-free rate after retrograde intrarenal surgery and other parameters was analyzed using the Mann–Whitney test, Spearman correlation, and logistic regression. RESULTS: The median age of the patients was 11.8 years. Computed tomography revealed a median stone size of 13.2 mm and density of 1481 HU. After primary retrograde intrarenal surgery, complete stone clearance was achieved in 49 children (77.81%); after repeat intervention for residual fragments, the overall stone-free rate reached 93.66% (59 patients). Only 2 patients (3.17%) developed ureteral colic due to residual ureteral fragments after stent removal, requiring urgent intervention. Statistically significant predictors of residual fragments included initial stone size 1.6 cm on computed tomography and simultaneous stone location in both the pelvis and calyx (p 0.05). No association was found between stone-free rate and patient age. CONCLUSION: The method of retrograde intrarenal surgery in children demonstrated a high stone-free rate and a low incidence of significant complications.