Assessment of a novel bendable-tip ureteral access sheath with integrated suction: an in vitro study

Surgical management of urinary stones has significantly evolved with the advent of extracorporeal shockwave lithotripsy, flexible ureterorenoscopy (fURS), and percutaneous nephrolithotomy. For lower pole stones larger than 1 cm, the choice between fURS and miniaturized percutaneous nephrolithotomy remains debated. fURS with ureteric access sheaths (UAS) is a widely utilized technique, but fragment clearance is challenging in unfavorable anatomical conditions and/or lower pole stones. This study compares a novel flexible suction UAS (FANS) with a standard UAS in an in vitro model of lower pole stones. An in vitro experiment was conducted using an anatomical model of the urinary tract with artificial stones simulating complex 1-cm lower pole stones. Fourteen procedures were performed using either a 12/14 Fr diameter standard UAS or FANS. Every experiment was performed by a single surgeon using a 8.4 Fr single-use digital flexible ureteroscope and holmium:YAG laser set at 0.5 J, 25 Hz, and short pulse with a 272 μm fiber. Operative times, stone clearance rates, lasering times, were recorded and the residual stone masses (> 2 mm) was quantified. Complete stone clearance was achieved in 5 out of 7 procedures using FANS while no complete stone clearance was achieved using the standard UAS. The median laser time [27:33 (26:06-28:24) vs 24:02 (21:25-25:04) mm:ss, p = 0.017] and total energy output energy [20663 (19,575-21,325) vs 18,270 (16,069-18,931) J, p = 0.017] were significantly lower in the FANS group (p = 0.017), and the operative time was comparable. This in vitro experiment suggests that fURS with novel FANS may improve stone clearance and improve laser efficiency when compared to the standard UAS, without increasing operative times. Further clinical trials are warranted to confirm these findings.