Kidney StonesMINI-FURSNCT07798336
6.3Fr Versus 7.5Fr Mini-Flexible Ureteroscopy for Renal Stones (MINI-FURS)
A study testing 6.3Fr Mini-Flexible Ureteroscope and 7.5Fr Mini-Flexible Ureteroscope in people with Kidney Stones and Nephrolithiasis, run by Sault Area Hospital at 1 site in Canada.
Trial summary
This prospective, randomized, single-blinded, non-inferiority clinical trial will compare the clinical outcomes and cost-effectiveness of two mini-flexible ureteroscopes (6.3Fr and 7.5Fr) used during flexible ureteroscopy for the treatment of renal stones. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Kidney Stones, Nephrolithiasis, Renal Calculi
- What is being tested?
- 6.3Fr Mini-Flexible Ureteroscope and 7.5Fr Mini-Flexible Ureteroscope
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 308 participants
- Where
- 1 siteCanada
- Study dates
- 1 Oct 2026to 31 Aug 2028
- Phase
- Interventional
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
Who may be able to join
- Scheduled to undergo flexible ureteroscopy for renal stones.
- Renal stone size ≤15 mm in the greatest dimension.
- No indwelling ureteral stent at the time of surgery.
- Able and willing to provide written informed consent.
Who cannot join
- Anatomical abnormalities of the urinary tract (e.g., ureteral stricture, horseshoe kidney, ectopic kidney).
- Solitary kidney.
- Pregnancy.
- Stones located within a calyceal diverticulum.
- Any condition that, in the opinion of the investigator, would interfere with study participation or follow-up.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Canada1 site
Sault Area Hospital
Sault Ste. Marie, Ontario, P6B 0A8
Yasser A Noureldin, MD, PhD (Urol), FEBU, FACS, 416-318-2239, ynoureldin@nosm.ca
Ali O Abdelhady, MD, 5042664549, aliabdelhady453@gmail.com
About this study
Official title: Outcomes and Cost-Effectiveness of 6.3French vs. 7.5French Mini-Flexible Ureteroscopy in the Treatment of Renal Stones: A Non-Inferiority, Prospective, Randomized, Single-Blinded Study
This prospective, randomized, single-blinded, non-inferiority clinical trial will compare the clinical outcomes and cost-effectiveness of two mini-flexible ureteroscopes (6.3Fr and 7.5Fr) used during flexible ureteroscopy for the treatment of renal stones. Adult patients with renal stones up to 15 mm who are scheduled to undergo flexible ureteroscopy will be randomly assigned to one of the two study groups. The primary objectives are to compare stone-free rates and the ability to achieve primary renal access without preoperative ureteral stenting. Secondary outcomes include operative time, fluoroscopy use, ureteral trauma, postoperative stenting, pain, complications, emergency department visits, need for additional procedures, hospital stay, and cost-effectiveness. The results of this study are expected to provide high-quality evidence to guide the selection of mini-flexible ureteroscopes and improve the quality, safety, and value of surgical care for patients with kidney stones.
Read the detailed description
Renal stone disease is a common condition with an increasing global incidence. Flexible ureteroscopy has become one of the standard treatments for renal stones because it provides excellent stone clearance with a minimally invasive approach. Recent technological advances have led to the development of mini-flexible ureteroscopes with smaller diameters, which may facilitate easier access to the kidney while reducing ureteral trauma and the need for preoperative ureteral stenting.
Although both 6.3Fr and 7.5Fr mini-flexible ureteroscopes are currently available for clinical use, there is limited high-level evidence comparing their clinical performance and cost-effectiveness. This prospective, randomized, single-blinded, non-inferiority trial aims to compare these two ureteroscope sizes in adult patients undergoing flexible ureteroscopy for renal stones.
Eligible participants will be randomized in a 1:1 ratio to undergo flexible ureteroscopy using either a 6.3Fr or a 7.5Fr mini-flexible ureteroscope. All procedures will be performed using standardized surgical techniques by experienced endourologists.
The primary outcomes are stone-free rate at one month after surgery and successful primary renal access without preoperative ureteral stenting. Secondary outcomes include operative time, fluoroscopy utilization, intraoperative ureteral trauma, postoperative ureteral stenting, postoperative pain, complications classified using the Clavien-Dindo system, emergency department visits, hospital length of stay, need for secondary procedures, and cost-effectiveness from the hospital payer perspective.
The investigators hypothesize that the 6.3Fr mini-flexible ureteroscope will improve primary renal access while reducing ureteral trauma, fluoroscopy exposure, postoperative stenting, and overall healthcare costs without compromising stone-free rates. The findings of this study may help establish evidence-based recommendations for selecting mini-flexible ureteroscopes and optimize the surgical management of patients with renal stone disease.
- Conditions
- Kidney Stones, Nephrolithiasis, Renal Calculi
- Being tested
- 6.3Fr Mini-Flexible Ureteroscope, 7.5Fr Mini-Flexible Ureteroscope
- Keywords
- Flexible ureteroscopy, Mini-flexible ureteroscopy, Mini ureteroscope, Ureteroscopy, Renal stones, Kidney stones, Nephrolithiasis, Endourology, Laser lithotripsy, Thulium fiber laser, Randomized controlled trial, Stone free rate, Cost effectiveness, Ureteroscope 6.3Fr, Ureteroscope 7.5Fr
- Medical subject headings
- Kidney Calculi, Nephrolithiasis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
6.3Fr Mini-Flexible UreteroscopeDevice
Use of a disposable 6.3Fr mini-flexible ureteroscope during flexible ureteroscopy for renal stone treatment
7.5Fr Mini-Flexible UreteroscopeDevice
Use of a disposable 7.5Fr mini-flexible ureteroscope during flexible ureteroscopy for renal stone treatment
| Study group | Role | What they receive |
|---|---|---|
| 6.3Fr Mini-Flexible Ureteroscope | Experimental | Participants randomized to this arm will undergo flexible ureteroscopy using a 6.3Fr mini-flexible ureteroscope for the treatment of renal stones according to the study protocol Receives: Device: 6.3Fr Mini-Flexible Ureteroscope |
| 7.5Fr Mini-Flexible Ureteroscope | Active comparator | Participants randomized to this arm will undergo flexible ureteroscopy using a 7.5Fr mini-flexible ureteroscope for the treatment of renal stones according to the study protocol Receives: Device: 7.5Fr Mini-Flexible Ureteroscope |
What is being measured
The primary outcome is the main question the study is designed to answer.
Stone Free Rate
Stone-free status defined as the absence of residual stone fragments greater than 2 mm on non-contrast CT KUB
Measured: 1 month after surgery
Primary Renal Access Success Rate
Successful passage of the flexible ureteroscope into the renal collecting system without the need for preoperative ureteral stenting
Measured: Perioperative/Periprocedural
Secondary outcomes (10)
Operative Time
Total operative time measured from insertion of the ureteroscope until completion of the procedure
Measured: During surgery
Intraoperative Fluoroscopy Use
Fluoroscopy utilization during the procedure, including fluoroscopy time
Measured: During surgery
Intraoperative Ureteral Trauma as Assessed by the Traxer Ureteral Injury Scale
Ureteral trauma will be assessed using the Traxer Ureteral Injury Scale, graded from 0 to 3, where Grade 0 indicates no observable ureteral injury and Grade 3 indicates the most severe ureteral injury. Higher scores indicate greater severity of ureteral injury.
Measured: Perioperative/Periprocedural
Postoperative Ureteral Stenting Rate
Percentage of participants requiring ureteral stent placement at the end of surgery
Measured: Immediately after surgery
Postoperative Pain as Assessed by the Visual Analog Scale
Postoperative pain will be assessed using the Visual Analog Scale, ranging from 0 to 10, where 0 represents no pain and 10 represents the worst possible pain. Higher scores indicate greater pain.
Measured: 6, 24, and 48 hours after surgery
Postoperative Complications
Complications graded using the Clavien-Dindo Classification
Measured: Up to 30 days after surgery
Emergency Department Visits
Emergency department visits related to the procedure
Measured: Within 2 weeks after surgery
Hospital Length of Stay
Length of hospital stay measured in hours from admission for the index ureteroscopy procedure to hospital discharge.
Measured: Perioperative/Periprocedural
Need for Secondary Procedures
Requirement for additional stone-related procedures
Measured: Up to 1 month after surgery
Incremental Cost-Effectiveness Ratio Comparing 6.3Fr and 7.5Fr Mini-Flexible Ureteroscopes
The incremental cost-effectiveness ratio (ICER) will compare the additional direct medical cost associated with the 6.3Fr versus 7.5Fr mini-flexible ureteroscope relative to the incremental clinical effectiveness. Direct medical costs will include ureteroscope acquisition costs, repair costs, procedure-related disposables, operating room time, hospital stay, management of complications, readmissions, and secondary procedures. Clinical effectiveness will be assessed primarily using stone-free and successful primary access outcomes.
Measured: From surgery through 30 days after surgery
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted1 Sep 2026
- Study start1 Oct 2026 (estimated)
- Primary completion29 Feb 2028 (estimated)
- Study completion31 Aug 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (7)Papers the sponsor has linked to this study.
- Other trials for Kidney StonesStudies 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
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Participants will be randomized in a 1:1 ratio to undergo flexible ureteroscopy using either a 6.3Fr or a 7.5Fr mini-flexible ureteroscope. Outcomes will be compared between the two parallel groups
- Masking
- Double blind
- Who is masked
- Participant, Outcomes assessor
- Enrolment
- 308 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Sault Area Hospital
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Yasser A Noureldin, MD, PhD, Principal investigator, Urologist, Sault Area Hospital, Sault Ste. Marie, ON, Canada, and Assistant Professor of Urology, Northern Ontario School of Medicine University, ON, Canada
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07798336
- Sponsor's protocol ID
- 2026-03-01
- Acronym
- MINI-FURS
- Status last verified
- Aug 2026
- First submitted
- 24 Aug 2026
- Last updated
- 4 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant data will not be made available to other researchers. This decision reflects applicable institutional policies, participant privacy and confidentiality requirements, ethical considerations, and the terms of informed consent. De-identified aggregate study results will be reported in accordance with applicable reporting requirements.
Publications
Ebner B, Blajan I, Westphal JR, Papadopoulos I, Ivanova T, Karatas D, Happe M, Volz Y, Stief CG, Apfelbeck M, Chaloupka M. Feasibility and Safety of Primary Ureteroscopy with Single-Use Flexible Ureteroscope HU30M (6.3 Fr, HugeMed): An Initial Experience. Diagnostics (Basel). 2025 Oct 5;15(19):2522. doi: 10.3390/diagnostics15192522.
PubMed 41095741Geavlete B, Ene C, Iordache V, Geavlete P. Initial Experience with the New Super Thin Single-use Pusen Flexible Ureteroscope 7.5 Fr in Renal Stones Endoscopic Treatment. Chirurgia (Bucur). 2021 May-Jun;116(3):354-360. doi: 10.21614/chirurgia.116.3.354.
PubMed 34191717Hu H, Qin M, Yang L, Hu H, Qin G, Qiu M, Gao Y, Dou J, Wu T, Long P, Zhang W. Analysis of the effectiveness and safety of 7.5 Fr ultra-thin flexible ureteroscope combined with a tip-flexible suctioning ureteral access sheath for the treatment of kidney stones. Int Urol Nephrol. 2025 Mar;57(3):817-823. doi: 10.1007/s11255-024-04269-1. Epub 2024 Nov 9.
PubMed 39521733Geavlete PA, Bulai CA, Multescu RD, Ene CV, Militaru A, Punga AA, Geavlete BF. Early clinical outcomes using a 6.3 Fr single use ureteroscope compared to a 7.5 Fr device. Sci Rep. 2025 May 2;15(1):15362. doi: 10.1038/s41598-025-00515-3.
PubMed 40316636Alharran AM, Alajmi SA, Hussain AA, Alajmi MS, Hashim S, Alwazzan LT, Alaradi H. Efficacy and Safety of 6.3 Fr Versus 7.5 Fr Single-Use Flexible Ureteroscopes for Upper Urinary Tract Stones: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Medicina (Kaunas). 2025 Nov 26;61(12):2103. doi: 10.3390/medicina61122103.
PubMed 41470105Assimos DG. Urolithiasis/Endourology. J Urol. 2021 Sep;206(3):765-767. doi: 10.1097/JU.0000000000001904. Epub 2021 Jun 11. No abstract available.
PubMed 34111940Zhang L, Zhang X, Pu Y, Zhang Y, Fan J. Global, Regional, and National Burden of Urolithiasis from 1990 to 2019: A Systematic Analysis for the Global Burden of Disease Study 2019. Clin Epidemiol. 2022 Aug 15;14:971-983. doi: 10.2147/CLEP.S370591. eCollection 2022.
PubMed 35996396