Prospective Comparison of Thulium and Holmium Laser Lithotripsy for the Treatment of Upper Urinary Tract Lithiasis

BACKGROUND: Lithotripsy with holmium:yttrium-aluminum-garnet (Ho:YAG) laser is the current gold standard for treating stones of the upper urinary tract (UUT). The recently introduced thulium fiber laser (TFL) has the potential to be more efficient and as safe as Ho:YAG. OBJECTIVE: To compare the performance and complications between Ho:YAG and TFL for UUT lithotripsy. DESIGN, SETTING, AND PARTICIPANTS: This was a prospective single-center study of 182 patients treated between February 2021 and February 2022. In a consecutive approach, laser lithotripsy was performed via ureteroscopy with Ho:YAG for 5 mo, and then with TFL for 5 mo. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Our primary outcome was stone-free (SF) status at 3 mo after ureteroscopy with Ho:YAG versus TFL lithotripsy. Secondary outcomes were complication rates and results regarding the cumulative stone size. Patients were followed at 3 mo with abdominal imaging (ultrasound or computed tomography). RESULTS AND LIMITATIONS: The study cohort comprised 76 patients treated with Ho:YAG laser and 100 patients treated with TFL. Cumulative stone size was significantly higher in the TFL than in the Ho:YAG group (20.4 vs 14.8 mm; p = 0.01). SF status was similar in both groups (68.4% vs 72%; p = 0.06). Complication rates were comparable. In subgroup analysis, the SF rate was significantly higher (81.6% vs 62.5%; p = 0.04) and the operative time was shorter for stones measuring 1–2 cm, whereas the results were similar for stones <1 cm and >2 cm. The lack of randomization and single-center design are the main limitations of the study. CONCLUSIONS: TFL and Ho:YAG lithotripsy are comparable in terms of the SF rate and safety for the treatment of UUT lithiasis. According to our study, for a cumulative stone size of 1–2 cm, TFL is more effective than Ho:YAG. PATIENT SUMMARY: We compared the efficiency and safety of two laser types for the treatment of stones in the upper urinary tract. We found that stone-free status at 3 months did not significantly differ between the holmium and thulium lasers.