Long-term Safety of UAS-assisted vs Sheathless RIRS in Non-prestented Patients

This retrospective comparative cohort study will evaluate long-term safety outcomes of ureteral access sheath-assisted versus sheathless retrograde intrarenal surgery (RIRS) in adult patients with renal stones measuring ≤20 mm who were not prestented before the index procedure. Eligible patients treated at Al-Azhar University Hospitals between January 2020 and December 2025 will be identified from operative and medical records and then invited for active long-term follow-up. Participants will be categorized according to whether a ureteral access sheath was used during the initial RIRS. The primary outcome is the composite occurrence of delayed ipsilateral ureteral stricture or new/progressive ipsilateral hydronephrosis at least 12 months after surgery. Secondary outcomes include intraoperative ureteral injury, postoperative complications, stone-free rate, renal function, emergency visits, readmissions, and need for additional intervention. Propensity score methods and multivariable analyses will be used to reduce confounding due to nonrandom treatment allocation.

Inclusion criteria

• Age ≥18 years at time of index RIRS.
• Primary RIRS performed at Al-Azhar University Hospitals between Jan 1, 2020 and Dec 31, 2025.
• Renal stone(s) with maximum diameter ≤20 mm on preoperative imaging.
• No ipsilateral ureteral stent or nephrostomy before index RIRS.
• Documented operative record specifying whether a UAS was used.
• At least 12 months elapsed since index RIRS.
• Available contact information allowing invitation for active follow-up.

Exclusion criteria

• Primary ureteral stone treated during the same procedure.
• Staghorn or >20 mm stone burden.
• Prior ipsilateral ureteral stricture or reconstructive surgery.
• Congenital renal/ureteral anomalies affecting outcome (e.g., horseshoe kidney, duplicated system).
• Incomplete operative or preoperative imaging records that preclude determination of eligibility or exposure (UAS use).
• Additional ipsilateral ureteral procedure during follow-up that independently causes ureteral narrowing.
• Refusal to participate in active follow-up or failure to attend after repeated attempts.