6.3Fr Versus 7.5Fr Mini-Flexible Ureteroscopy for Renal Stones (MINI-FURS)

Renal stone disease is a common condition with an increasing global incidence. Flexibleureteroscopy has become one of the standard treatments for renal stones because itprovides excellent stone clearance with a minimally invasive approach. Recenttechnological advances have led to the development of mini‐flexible ureteroscopes withsmaller diameters, which may facilitate easier access to the kidney while reducingureteral trauma and the need for preoperative ureteral stenting.Although both 6.3Fr and 7.5Fr mini‐flexible ureteroscopes are currently available forclinical use, there is limited high‐level evidence comparing their clinical performanceand cost‐effectiveness. This prospective, randomized, single‐blinded, non‐inferioritytrial aims to compare these two ureteroscope sizes in adult patients undergoing flexibleureteroscopy for renal stones.Eligible participants will be randomized in a 1:1 ratio to undergo flexible ureteroscopyusing either a 6.3Fr or a 7.5Fr mini‐flexible ureteroscope. All procedures will beperformed using standardized surgical techniques by experienced endourologists.The primary outcomes are stone‐free rate at one month after surgery and successfulprimary renal access without preoperative ureteral stenting. Secondary outcomes includeoperative time, fluoroscopy utilization, intraoperative ureteral trauma, postoperativeureteral stenting, postoperative pain, complications classified using the Clavien‐Dindosystem, emergency department visits, hospital length of stay, need for secondaryprocedures, and cost‐effectiveness from the hospital payer perspective.The investigators hypothesize that the 6.3Fr mini‐flexible ureteroscope will improveprimary renal access while reducing ureteral trauma, fluoroscopy exposure, postoperativestenting, and overall healthcare costs without compromising stone‐free rates. Thefindings of this study may help establish evidence‐based recommendations for selectingmini‐flexible ureteroscopes and optimize the surgical management of patients with renalstone disease.