An observational study in Renal Stone Disease, Ureteral Stricture and Hydronephrosis, sponsored by Al-Azhar University. Recruiting at 1 site in Egypt. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-08-18.
Sponsored by Al-Azhar University · Observational
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.
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.
Exclusion Criteria:
Adult patients with renal stones ≤20 mm who underwent primary retrograde intrarenal surgery using a ureteral access sheath and had no preoperative ipsilateral ureteral stent or nephrostomy.
Procedure: Ureteral access sheath-assisted RIRS
Adult patients with renal stones ≤20 mm who underwent primary retrograde intrarenal surgery without a ureteral access sheath and had no preoperative ipsilateral ureteral stent or nephrostomy.
Procedure: Sheathless RIRS
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.
RIRS 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.
Time frame: At least 12 months after the index RIRS procedure
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
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Al-Azhar University