Flexible and Navigable Suction Ureteral Access Sheath (FANS) vs Conventional Access Sheaths in RIRS: A Prospective Randomized Study.

Overview

Kidney stones located in the kidney are commonly treated using a minimally invasive procedure called retrograde intrarenal surgery (RIRS). During this procedure, a ureteral access sheath is often used to facilitate repeated access to the kidney, improve visualization, and allow irrigation fluid to drain. Newer access sheaths have been developed with flexible distal tips and built-in suction capabilities, which may help reduce operative time by improving visibility and removing stone fragments and irrigation fluid more efficiently. This prospective randomized study compared a flexible and navigable suction ureteral access sheath with a conventional ureteral access sheath in adult patients undergoing RIRS for kidney stones measuring 10 mm or larger. Participants were randomly assigned to one of the two access sheath types. The primary objective of the study was to evaluate whether the use of a suction-enabled access sheath reduces operative time. Secondary objectives included assessment of complications, length of hospital stay, stone-free rate, and need for additional interventions.

This was a prospective, single-center, randomized controlled trial conducted at a tertiary referral endourology center. Adult patients (≥18 years) with renal stones measuring 10 mm or greater and scheduled to undergo retrograde intrarenal surgery (RIRS) under general anesthesia were eligible for inclusion. Participants were randomized in a 1:1 ratio to undergo RIRS using either a flexible and navigable suction ureteral access sheath (FANS group) or a conventional ureteral access sheath (control group). Randomization was performed using a computer-generated sequence with allocation concealment via sealed opaque envelopes. Blinding of the operating surgeon was not feasible due to the nature of the devices used. All procedures were performed by experienced endourologists using standardized surgical techniques. Flexible ureteroscopy was performed with a digital ureteroscope, and stone fragmentation was achieved using a Holmium:YAG laser in dusting mode. In the suction access sheath group, negative pressure suction was applied through the sheath according to manufacturer guidelines. Irrigation parameters were standardized across both study arms. The primary outcome measure was operative time, defined as the interval from insertion of the first endoscopic instrument through the urethra to removal of the final instrument at the end of the procedure. Secondary outcome measures included intraoperative and postoperative complications (classified using the Clavien-Dindo system), ureteral wall injury, length of hospital stay, stone migration, and stone-free rate. Stone-free status was defined as the absence of residual fragments greater than 2 mm on postoperative imaging. Preoperative assessment included non-contrast computed tomography to evaluate stone size, location, and burden. Postoperative imaging was performed using kidney-ureter-bladder radiography or renal ultrasound approximately two weeks after surgery. The study was approved by the Institutional Review Board of Barzilai University Medical Center, and all participants provided written informed consent prior to enrollment.