Thulium fiber laser vs Ho:YAG in RIRS: a prospective randomized clinical trial assessing the efficacy of lasers and different fiber diameters (150 m and 200 m)

Introduction The aims of the study: (1) to compare the Super Pulse Thulium Fiber Laser (SP TFL) and the holmium: yttrium-aluminium-garnet (Ho:YAG) lasers in retrograde intrarenal surgery (RIRS); (2) to compare the efficacy of SP TFL laser fibers of different diameters (150 mu m and 200 mu m).Methods A prospective randomized single-blinded trial was conducted. Patients with stones from 10 to 20 mm were randomly assigned RIRS in three groups: (1) SP TFL (NTO IRE-Polus, Russia) with fiber diameter of 150 mu m; (2) SP TFL with 200-mu m fiber; and (3) Ho:YAG (Lumenis, USA) with 200-mu m fiber.Results Ninety-six patients with kidney stones were randomized to undergo RIRS with SP TFL using a 150-mu m fiber (34 patients) and a 200-mu m fiber (32 patients) and RIRS with Ho:YAG (30 patients). The median laser on time (LOT) in the 200-mu m SP TFL group was 9.2 (6.2-14.6) min, in 150-mu m SP TFL-11.4 (7.7-14.9) min (p = 0.390), in Ho:YAG-14.1 (10.8-18.1) min (p = 0.021). The total energy consumed in 200-mu m SP TFL was 8.4 (5.8-15.2) kJ; 150-mu m SP TFL - 10.8 (7.3-13.5) kJ (p = 0.626) and in Ho:YAG-15.2 (11.1-25.3) kJ (p = 0.005).Conclusions Irrespective of the density, RIRS with SP TFL laser has proven to be both a safe and effective procedure. Whilst the introduction of smaller fibers may have the potential to reduce the duration of surgery, SP TFL results in a reduction in the LOT and total energy for stone ablation in RIRS compared with Ho:YAG.