Efficacy of thulium fiber laser litothripsy on large renal stones (> 1000 mm³) according to Hounsfield units: a prospective single-center study

This study evaluated the efficacy and safety of Thulium Fiber Laser (TFL) lithotripsy based on stone density and factors affecting success in retrograde intrarenal surgery (RIRS) for renal calculi > 1000 mm3. Eighty-one patients who underwent RIRS with TFL for renal calculi > 1000 mm3 were evaluated prospectively and categorized into two groups based on stone density [Group 1:<1000 Hounsfield Units (HU); Group 2:≥1000 HU]. Demographic data, stone-free rates (SFRs), need for second RIRS, and complications were also recorded. Laser parameters, including lasing time, energy usage, ablation speed, efficiency, and energy consumption, were calculated. Mean HU values differed significantly between groups (731.65 ± 220.54 vs. 1207.92 ± 147.75,p = 0.001). Laser energy consumption was lower in group 2 (14.83 ± 10.15 vs. 18.01 ± 16.02 J/mm3,p = 0.045).No significant differences were observed in the other laser parameters (ablation efficiency, ablation speed, total energy used). Need for second RIRS rates were similar (26.83% vs. 30.00%,p = 0.752). SFRs after first and second RIRS were comparable between the groups (53.66% vs. 40.00%,p = 0.218; 70.73% vs. 57.50%,p = 0.214).Laser ablation efficiency (p = 0.004), ablation speed (p = 0.036), and operative time (p < 0.001) positively correlated with SFR in univariate analysis, but not in multivariate analysis.Stone location, and preoperative double J stent presence did not affect SFRs. The complication rate was 12.35%, with most complications being mild (Clavien I and II). TFL is effective and safe for treating large kidney stones using RIRS. Stone density did not significantly affect the outcomes, suggesting TFL’s versatility across different stone compositions. TFL lithotripsy is a promising option for the treatment of large renal calculi. NCT07153978.