Ho: YAG Laser Settings in RIRS for Low-Density Renal Pelvis Stones

INTRODUCTION: The aim of this study was to compare dusting-like and fragmentation-like holmium: yttrium-aluminum-garnet laser settings during retrograde intrarenal surgery in patients with renal pelvis stones measuring 10–20 mm and Hounsfield units <1000.
METHODS: This retrospective study included 182 adult patients undergoing retrograde intrarenal surgery for solitary renal pelvis stones between January 2022 and November 2025. Patients were treated using either low-energy/high-frequency (0.4 J × 45 Hz) or high-energy/low-frequency (1.5 J × 12 Hz) laser settings. Both protocols delivered comparable total power (18 W). No active basket extraction was performed. The primary outcome was stone-free status at 4–6 weeks, defined as residual fragments ≤2 mm on low-dose computed tomography.
RESULTS: A total of 182 patients were included (0.4 J × 45 Hz: n=89; 1.5 J × 12 Hz: n=93). Baseline characteristics were comparable. Median operative time was shorter in the low-energy/high-frequency group (55 [45–65] min vs 61 [52–70] min, p<0.001). Laser activation time was longer in this group (26.0 [24.0–28.0] vs 24.0 [21.0–29.0] min, p<0.001). Stone-free rates at 4–6 weeks were higher (93.3% vs 86.0%, p=0.048). Complication rates were low and similar (4.5% vs 6.5%, p=0.748).
DISCUSSION AND CONCLUSION: In this retrospective cohort, low-energy/high-frequency Ho: YAG laser settings were associated with significantly shorter operative time and higher early stone-free rates at 4–6 weeks postoperatively, suggesting that pulse modulation—rather than total power alone—may influence lithotripsy efficiency in low-density stones.

Keywords: Dusting, Fragmentation, Hounsfield unit, Ho: YAG laser, Retrograde intrarenal surgery, Renal pelvis stone