Second-look flexible ureteroscopy after RIRS - Holmium Moses versus TFL (Soltive)

Retrograde intrarenal surgery (RIRS) is nowadays more and more indicated in pyelocaliceal stones. Holmium and Thulium lasers are the main lasers used. Fragmenting (basketing) or dusting, despite the new technology, still have residual stones (even having 250 microns). This study evaluates second-look flexible ureteroscopy for residual fragments. We analyzed 246 patients (October 2020-March 2022) on which we used Moses Holmium technology (187 cases) in Group 1 and Soltive Laser System (59 cases) in Group 2. The average stone size was 13.1 mm (range 11-29), and the average stone density was 1026 HU (range 870-1752). We used 270 µm for Ho: YAG laser and 150 µm for TFL. For Holmium, we applied energy 0.4J and frequency 80 Hz. For TFL, we applied fine dusting (0.15 J/100 Hz) and dusting (0.5 J/30 Hz). After three months, we practiced the second flexible ureteroscopy. Both groups were compared for completely visual stone-free rates. Stone-free rate at 3 months (second flexible ureteroscopy) was 86.63% (n=162/187) in Group 1 and 96,61% (n=57/59) in Group 2, respectively. The stone-free correlation with the CT preoperative evaluation was 160/187-85.56% for Holmium and 55/59-93.22% for TFL. We found residual stones after the second flexible ureteroscopy in 25 cases after Holmium laser treatment and only in 2 cases after TFL. In all these cases, we finally obtained zero residual stones. The second flexible ureteroscopy could achieve complete residual stone removal and real stone-free status. Despite a slight difference between these two laser technologies, the second look decreases the residual fragments.