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

Al-Azhar University1,200 enrolled

Overview

This retrospective comparative cohort study will include adult patients who underwent primary RIRS for renal stones ≤20 mm at Al-Azhar University Hospitals between January 2020 and December 2025. Patients will be classified by whether a ureteral access sheath (UAS) was used during the index RIRS, and all eligible patients will be invited for active long-term follow-up (minimum 12 months) to assess the composite outcome of delayed ipsilateral ureteral stricture or new/progressive ipsilateral hydronephrosis and other safety and efficacy outcomes. Propensity-score methods and adjusted regression analyses will be used to control confounding.

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.

Study Type

OBSERVATIONAL

Enrollment

1,200

Conditions

Renal Stone Disease Ureteral Stricture

Interventions

Ureteral access sheath-assisted RIRSPROCEDURE

Retrograde intrarenal surgery (RIRS) performed with placement of a ureteral access sheath during the initial procedure. Details recorded: sheath diameter (Fr), length, manufacturer/model, insertion success, number of insertion attempts, need for ureteral dilation, intraoperative findings.

Sheathless RIRSPROCEDURE

RIRS performed without placement of a ureteral access sheath. Details recorded: guidewire use, ureteral dilation, access difficulty, intraoperative findings.

Eligibility

Sex: ALLMin age: 18 Years

Medical Language ↔ Plain English

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.

Outcomes

Primary Outcomes

Composite outcome: delayed ipsilateral ureteral stricture or new/progressive ipsilateral hydronephrosis.

Incidence of the composite primary outcome consisting of either delayed ipsilateral ureteral stricture or new/progressive ipsilateral hydronephrosis after retrograde intrarenal surgery (RIRS). Delayed ureteral stricture will be defined by imaging or functional evidence of treated-ureter narrowing, including CT urography, retrograde pyelography, diagnostic ureteroscopy, diuretic renography, persistent/progressive upper-tract obstruction, or need for therapeutic intervention such as ureteral stenting, balloon dilation, endoureterotomy, or reconstructive surgery. New/progressive hydronephrosis will be defined as hydronephrosis absent preoperatively or increased in severity after RIRS, not explained by residual or recurrent stone disease or another non-study cause.

Time frame: At least 12 months after the index RIRS procedure

Secondary Outcomes

Intraoperative ureteral injury

Incidence and severity of ureteral injury during the index RIRS procedure, documented from operative records. Injury will be recorded according to the surgeon's description and, when available, the Traxer and Thomas classification.

Time frame: During the index RIRS procedure

Stone-free rate

Proportion of patients with complete stone clearance on postoperative imaging, with residual fragments categorized according to the predefined imaging threshold used in the study.

Time frame: 4 to 12 weeks after the index RIRS procedure

Postoperative infectious complications

Incidence of postoperative urinary tract infection, fever, or sepsis documented during follow-up after the index RIRS procedure.

Time frame: From surgery to 30 days after surgery, and during long-term follow-up up to 12 months

Change in serum creatinine

Change in serum creatinine from baseline to 12 months after the index RIRS procedure.

Time frame: Baseline and 12 months after the index RIRS procedure

Change in estimated glomerular filtration rate

Change in estimated glomerular filtration rate, calculated using the prespecified creatinine-based equation, from baseline to 12 months after the index RIRS procedure.

Time frame: Baseline and 12 months after the index RIRS procedure

Additional stone-related procedures

Incidence of auxiliary procedures, retreatment, or other additional stone-related interventions performed after the index RIRS procedure.

Time frame: From surgery to 12 months after the index RIRS procedure