Dimitrios Diamantopoulos-Kogkas, Pavlos Georgiou, Christos Pitros, Chrysanthi Papageorgopoulou, Marios Papasotiriou, Nikolaos Karydis, Nikolaos Koutsoyiannis, Athina Mougiou, Konstantinos Katsanos, and Spyros Papadoulas. Vasc Specialist Int 2024;40:. https://doi.org/10.5758/vsi.240022

Background/Objectives: Recently, a 6.3 Fr single-use flexible ureteroscope (f-URS) was introduced to the market. The purpose of this pilot study is to present our experience with it during Endoscopic Combined Intrarenal Surgery (ECIRS) and to compare its performance with the conventional 7.5 Fr scope. Methods: For percutaneous access, renal puncture was performed in a nonpapillary approach. Regarding retrograde access, for the first group, a 7.5 Fr single-use f-URS was used, while for the second group, a 6.3 Fr single-use f-URS was utilized. Lithotripsy was primarily performed in an antegrade manner, using the Lithoclast Trilogy^®. In cases where stones could not be reached with a nephroscope, retrograde lithotripsy was performed with either a Holmium:YAG laser or a Thulium Fiber Laser. Results: In total, 45 patients were included. Of these, 23 patients underwent ECIRS with the 6.3 Fr f-URS and 22 with the 7.5 Fr f-URS. The mean operative time, fluoroscopy time and lasing time were 59.5 ± 5.6 min, 139.7 ± 14.2 s and 18.4 ± 2.7 min in the 6.3 Fr group and 57.1 ± 3.9 min, 133.8 ± 29.7 s and 18.6 ± 1.9 min in the 7.5 Fr group, respectively. Two patients in the 6.3 Fr group and three patients in the 7.5 Fr group experienced Grade II complications. Stone-free rates were 91.3% in the 6.3 Fr group versus 86.4% in the 7.5 Fr group. Conclusions: The use of a 6.3 Fr f-URS during ECIRS is potentially a feasible, safe and efficient approach. Both the 6.3 Fr and 7.5 Fr scopes were associated with comparable outcomes during ECIRS. Additional studies are needed so as to draw safer conclusions.