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.
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.
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).
Adult patients (≥18 years) who underwent primary RIRS for renal stones ≤20 mm without ipsilateral preoperative ureteral stenting or nephrostomy at Al-Azhar University Hospitals between Jan 1, 2020 and Dec 31, 2025; active follow-up performed ≥12 months after index procedure.
Cohort
Retrospective
Ureteral access sheath-assisted RIRS
Procedure/SurgeryRetrograde 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 RIRS
Procedure/SurgeryRIRS performed without placement of a ureteral access sheath. Details recorded: guidewire use, ureteral dilation, access difficulty, intraoperative findings.
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.
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.
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.
Postoperative infectious complications
Incidence of postoperative urinary tract infection, fever, or sepsis documented during follow-up after the index RIRS procedure.
Change in serum creatinine
Change in serum creatinine from baseline to 12 months after the index RIRS procedure.
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