CLINICAL OUTCOMES OF LASER LITHOTRIPSY FOR MANAGEMENT OF LARGE KIDNEY STONES

Abstract

The use of laser lithotripsy in the treatment of large renal stones (more than two centimeters) using flexible ureteroscopy continues to be a challenge, despite the development of holmium:yttrium-aluminum-garnet (Ho:YAG) lasers. The advancement of a thulium fiber laser (TFL) with a 1940 nm wavelength and a four-fold increased water absorption coefficient has the potential to enhance the ablation rate and safety. This meta-analysis aims to compare the outcomes of TFL and Ho:YAG laser lithotripsy for large renal calculi. We conducted a systematic review and meta-analysis of articles published between 1992 and December 2024 in PubMed, Scopus, Web of Science, and Cochrane Library online databases. We included 43 studies, 2,847 patients and a mean stone size of cm. The main outcomes of interest were stone-free rates (SFR), operation time, complications, stone retropulsion, ablation rate, thermal safety, and learning curve. Pooled effect sizes were calculated using random-effects meta-analyses. TFL had a greater three-month SFR than the Ho:YAG laser. The total operative time was less with TFL. TFL had a fourfold greater water absorption coefficient, reduced ablation, and a 4.28-fold reduction in stone retropulsion distance. TFL had significantly reduced maximum temperature rise in the kidney, resulting in reduced collateral damage. TFL had almost half the number of complications and a significant decrease in major complications (7.6% with Ho:YAG vs. 2.8% with TFL). TFL was more effective against all stones, but especially cystine (performance ratio 2.74) and brushite (performance ratio 2.62) stones. There was a shorter learning curve with TFL, with 24 cases and training versus 42 for the Ho:YAG laser. Thulium fiber laser lithotripsy via flexible ureteroscopy is superior to Ho:YAG laser for large renal stones (two centimeters or larger) with a higher stone-free rate, shorter duration of procedure, fewer complications, better thermal safety, and a quicker learning curve. TFL should be the preferred laser for retrograde intrarenal surgery (RIRS) for large stones.