Lower pole anatomy-guided rigid URS for pediatric stones using modified GMSV position

To assess the feasibility of rigid ureteroscopic lithotripsy in modified Galdakao-modified supine Valdivia (GMSV) position for pediatric lower-pole renal calculi and the impact of infundibulopelvic angle (IPA) on surgery.

A retrospective analysis of 55 children (April 2022-April 2025, mean age 6.8 ± 3.3 years; 29 males, 52.7 %) undergoing attempted rigid ureteroscopy in modified GMSV was done. Patients were grouped by conversion: 14 successful rigid ureteroscopy, 21 converted to flexible ureteroscopy, 20 to mini-PCN. Preoperative IPA was measured, and the three groups were compared in operative time, hospital stay, stone-free rate (SFR), and complications.

Compared with the PCN group, the rigid ureteroscopy group had significantly shorter operative time (60.9 ± 26.5 min vs. 117.5 ± 41.3 min, P < 0.05) and hospital stay (3.5 ± 2.2 days vs. 5.5 ± 1.9 days, P < 0.05), while no significant difference was observed between the rigid and flexible ureteroscopy groups. 2-week SFR: 85.7 % (rigid ureteroscopy), 71.4 % (flexible ureteroscopy), 55.0 % (PCN) (P = 0.2); 6-month SFR >90 % in all (P = 1). Complications were rare, with no significant differences between groups.

In conclusion, the modified GMSV position enables successful rigid ureteroscopic lithotripsy in selected pediatric lower-pole calculi (<2.0 cm, IPA >30°), successfully treating over a quarter of our cohort. This approach offers a less invasive alternative with significantly shorter operative time and hospital stay compared to PCN, and, compared to flexible ureteroscopy, the significant advantage of a much lower pre-stenting rate.