Which sucks more? Comparison of two novel direct-in-scope suction ureteroscopes to a conventional ureteroscope

Introduction : Novel Direct-In-Scope-Suction ureteroscopes (DISS-U) have recently been introduced to facilitate removal of small stone fragments. The purpose of this study was to compare two novel DISS-U to a conventional ureteroscope to determine efficiency for suctioning fluid and stone dust at different deflection angles. Methods Three disposable ureteroscopes were evaluated, including two DISS-U with 5.1-Fr and a 3.6-Fr channels, and were compared to a conventional ureteroscope with 3.6-Fr channel. For DISS-U trials, a conventional suction system was set at maximal settings and tested at deflection of 0, 90, and 140°, to simulate upper, interpolar, and lower pole kidney stone evacuation under 3 conditions (empty channel, 2.2-Fr basket, and 0.038 guidewire). For the conventional ureteroscope, suctioning was performed manually using a 60-mL Luer lock syringe. Five trials were performed to measure the time in seconds to remove 1 gram of CaOx density BegoStones (0.25, 0.5, and 1 mm) and 50-mL of saline. Results The 5.1-Fr DISS-U was the only scope that evacuated 0.5 mm stone fragments and evacuated them significantly faster from the upper and interpole compared to the lower pole (111.0 ± 27.7, 128.0 ± 29.1, and 377.7 ± 63.4 s at 0, 90, and 140°, respectively; p < 0.002). The 5.1-Fr DISS-U evacuated 1 g of dust faster than the 3.6 DISS-U and conventional ureteroscope at all angles ( p < 0.007). The 5.1-Fr DISS-U and the 3.6-Fr DISS-U required less suction time for 50 mL of saline compared to the conventional ureteroscope at all angles ( p < 0.001 for all). Using a 2.2-Fr basket increased suction time by 66.0% ( p < 0.001) for the 3.6-Fr DISS-U and by 44% ( p < 0.001) for the 5.1-Fr DISS-U, while the 0.038 guidewire increased suction time by 96% and 111%, respectively ( p < 0.001). No ureteroscope was able to suction 1 mm stone fragments without clogging. Conclusions The DISS ureteroscopes significantly outperformed the conventional ureteroscope in both suction speed and dust evacuation efficiency. The 5.1-Fr DISS-U demonstrated superior performance and is able to evacuate stone particles up to 0.5 mm.