Tip Bendable Suction Ureteral Access Sheath vs. Traditional Ureteral Access Sheath in Retrograde Intrarenal Stone Surgery (RIRS): Study Protocol of a Multicentre, Prospective, Single-blinded, Randomized Controlled Trial

Nephrolithiasis is the most common chronic kidney condition and affecting approximately one in every 10-17 people in the world[1,2]. Flexible ureteroscopy (f-URS) has become one of the most common treatments for ureteral and renal stones with minimal complications. The development of ureteral access sheath (UAS) is a significant advance in flexible ureteroscopic management of urinary stones. The UAS has two major advantages: 1) facilitating multiple entries into the renal collecting system without causing recurrent trauma to the ureter and permit expeditious basketing of multiple stone fragments, 2) improving the irrigation with better fluid outflow, thereby reducing the renal pelvic pressure (RPP) and risk of infectious complications.

The tip bendable suction ureteral access sheath (S-UAS) is a novel UAS that has good flexibility and deformability at the tip, which can passively bend (bend >90°) with the bending of f-URS and can connect to a vacuum suction device. Preliminary study showed that S-UAS can follow f-URS to cross the UPJ and into the renal pelvis and calices. S-UAS close to the stone can achieve complete stone-free status in RIRS. However, further clinical studies and comparisons with available techniques are required. This prospective, single-blinded, single-center, randomized control trial will evaluate the stone free rates, operative time, postoperative complications following RIRS with S-UAS. To the best of our knowledge, this is the first study to compare the clinical benefits of RIRS with S-UAS and traditional UAS.