FANS vs Standard Ureteral Access Sheath in fURS

Single-center, prospective, randomized, interventional, single blinded study. Participants with renal calculi undergoing ureterorenoscopy and laser lithotripsy will be randomized in a 1:1 ratio to receive either a standard ureteral access sheath (UAS) or the FANS (Flexible and Navigable Suction) sheath. Randomization will be stratified by stone characteristics, specifically stone density (≤1000 vs >1000 HU) and stone volume (<500 vs ≥500 mm³), as recorded on preoperative imaging, to reduce potential imbalance between study arms.

Inclusion criteria

• Participant is willing and able to provide written informed consent before any study-specific procedures are performed.
• Male or female, aged 18 years or older.
• Diagnosed with renal calculi ≥5 mm in diameter, confirmed by imaging, and eligible for fURS with laser lithotripsy according to European Association of Urology (EAU) guidelines.
• In stable general health and fit for elective endoscopic surgery under general anesthesia.
• Willing and able to comply with all study-related procedures, including follow-up imaging and clinical assessments.

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Exclusion criteria

• Solitary kidney (monorenal patients).
• Untreated positive urine culture or ongoing urinary tract infection not resolved with appropriate antibiotic therapy prior to surgery.
• Known anatomical abnormalities of the urinary tract that may interfere with ureteroscopic access or device placement (e.g., ureteral stricture, congenital malformations).
• Pregnancy or breastfeeding at the time of enrollment or planning pregnancy during the study period. In all female patients, a Gravindex test is performed on the day of admission; contraceptive measures are not required
• Concomitant ureteral stone
• Ureteral stenosis
• Known allergy or hypersensitivity to materials used in the investigational or control ureteral access sheath.
• Any severe comorbid condition (e.g., uncontrolled cardiovascular disease, severe coagulopathy, active malignancy) that in the opinion of the investigator would interfere with study participation or increase procedural risk.
• Any psychological, cognitive, or social condition that may limit the ability to provide informed consent or comply with follow-up procedures.