Magneto Ho:YAG laser versus Thulium Fiber Laser for laser lithotripsy during flexible ureteroscopy with a flexible and navigable ureteral access sheath.

Introduction: The continuous advances in laser technology for endoscopic lithotripsy have revolutionized the endourology. In order to achieve increasingly finer dust, new pulse modulations with lower peak power have emerged, such as the new magneto Ho:YAG laser (M-Ho:YAG). The aim of this study is to compare the intraoperative outcomes between thulium fiber laser (TFL) and M-Ho:YAG.

Materials and methods: A retrospective study was conducted of patients undergoing flexible ureteroscopy (RIRS) for non-complex kidney stones in the Hospital Aleman of Buenos Aires, Argentina. Groups were divided according to the laser technology used: Group 1 = M-Ho:YAG laser and Group 2 = TFL. We used a 10/12 Fr or 11/13 Fr flexible and navigable ureteral access sheath (FANS) in all patients. Stone-free rate (SFR) was defined as the absence of any fragments on a non-contrast computed tomography scan at 4 weeks after the procedure. In addition, according to the new definitions of laser ablative performance, the ablative efficiency was estimated as the stone volume per unit of energy (mm³/Joules), the lithotripsy efficacy as the stone volume per unit of operative time (mm3/min) and the laser energy consumption as the energy consumed per unit of stone volume (Joules/mm³).

Results: 127 patients were included (Group 1 = 51 and Group 2 = 76). There were no significant differences in demographic variables between both groups (sex, age, body mass index, and procedure laterality). Furthermore, there was no significant difference in stone volume or stone density between groups. Ablative efficacy (25.7 vs. 24.7, p = 0.49), efficiency (0.18 vs. 0.16, p = 0.76), and laser energy consumption (11.5 vs. 11.1, p = 0.68) were significantly comparable between both groups, as was the SFR (98% vs. 94.7%, p = 0.35).

Conclusion: In this first clinical comparison between both laser technologies, no significant differences were found in the most important intra- and postoperative results. Larger and randomized studies are required to confirm these outcomes.