Renal Stone DiseaseNCT07767773
Long-term Safety of UAS-assisted vs Sheathless RIRS in Non-prestented Patients
An observational study of Renal Stone Disease and Ureteral Stricture, run by Al-Azhar University at 1 site in Egypt.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Renal Stone Disease, Ureteral Stricture, Hydronephrosis
- What is being tested?
- Ureteral access sheath-assisted RIRS and Sheathless RIRS
- Type of treatment
- Surgery or procedure
- How many people
- 1,200 participants
- Where
- 1 siteEgypt
- Study dates
- 16 Aug 2026to 25 Dec 2027
- Phase
- Observational
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: 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.
Who may be able to join
- 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.
Who cannot join
- 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.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Egypt1 site, 1 recruiting
- Recruiting
Department of Urology, Al-Hussein and Sayed Galal University Hospitals, Al-Azhar University
Cairo
Abul-fotouh Ahmed, MD, +201001066756, abulfotouhahmed@yahoo.com
About this study
Official title: Long-Term Safety Outcomes of Ureteral Access Sheath-Assisted Versus Sheathless Retrograde Intrarenal Surgery for Renal Stones ≤20 mm in Non-Prestented Patients: A Retrospective Comparative Cohort Study With Active Follow-up
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.
Read the detailed description
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.
- Conditions
- Renal Stone Disease, Ureteral Stricture, Hydronephrosis, Urolithiasis, Retrograde Intrarenal Surgery, Ureteral Access Sheath
- Being tested
- Ureteral access sheath-assisted RIRS, Sheathless RIRS
- Medical subject headings
- Hydronephrosis, Urolithiasis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Ureteral access sheath-assisted RIRSProcedure or surgery
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 or surgery
RIRS performed without placement of a ureteral access sheath. Details recorded: guidewire use, ureteral dilation, access difficulty, intraoperative findings.
| Study group | Role | What they receive |
|---|---|---|
| UAS-assisted RIRS cohort. | 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. Receives: Procedure: Ureteral access sheath-assisted RIRS | |
| Sheathless RIRS cohort. | 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. Receives: Procedure: Sheathless RIRS |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: At least 12 months after the index RIRS procedure
Secondary outcomes (6)
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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: From surgery to 12 months after the index RIRS procedure
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted17 Aug 2026
- Study start16 Aug 2026
- Primary completion1 Dec 2027 (estimated)
- Study completion25 Dec 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Renal Stone DiseaseStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Retrospective
- Enrolment
- 1,200 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Al-Azhar University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Abul-fotouh Ahmed, Al-Azhar University
- Investigators
- Abul-fotouh Ahmed, Principal investigator, Department of Urology, Faculty of Medicine, Al-Azhar University, Cairo, Egypt
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07767773
- Sponsor's protocol ID
- UroAzhar_15_026
- Status last verified
- Aug 2026
- First submitted
- 11 Aug 2026
- Last updated
- 18 Aug 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No