Kidney Calculi (or Renal Calculi / Nephrolithiasis)TZ-RIRSNCT07906964
TZ-RIRS vs. C-RIRS for Kidney Stones
An observational study of Kidney Calculi (or Renal Calculi / Nephrolithiasis) and Renal Calculi, run by Government Super Speciality Hospital, Shireen Bagh, Srinagar at 1 site in India.
Trial summary
This study evaluates a new minimally invasive surgical technique for treating kidney stones called Triple-Zero Retrograde Intrarenal Surgery (TZ-RIRS). Traditionally, RIRS is performed using three standard tools: X-ray guidance (fluoroscopy), a plastic tube to keep the ureter open (ureteral access sheath or UAS), and… Read more about this study
- Who is it for?
- Ages 18 to 100 years
- Conditions the study is for
- Kidney Calculi (or Renal Calculi / Nephrolithiasis), Renal Calculi
- What is being tested?
- Triple-Zero Retrograde Intrarenal Surgery and Conventional Retrograde Intrarenal Surgery
- Type of treatment
- Surgery or procedure
- How many people
- 688 participants
- Where
- 1 siteIndia
- Study dates
- 1 Jan 2020to 31 Dec 2025
- Phase
- Observational
- Are there results?
- None posted in the registry
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 to 100 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Adult patients (≥18 years) with unilateral renal stones who were scheduled to undergo retrograde intrarenal surgery. The study included a prospective cohort of patients treated with the Triple-Zero technique and a retrospective cohort treated with conventional RIRS. Patients with complex anatomy, active infection, or those requiring preoperative stenting were excluded.
Who may be able to join
None listed.
Who cannot join
- Pregnancy
- Active urinary tract infection at the time of RIRS
- Ureteral stricture or concomitant ureteral stone not resolved
- Staghorn or partial staghorn calculi
- Multiple stones exceeding the size criteria
- Need for preoperative stenting due to obstruction or infection
- Solitary kidney
- Severe hydronephrosis (Society of Fetal Urology grade 4)
Trial locations and contacts
1 site in 1 country.
India1 site
Government Super Speciality Hospital, Srinagar
Srinagar, Jammu and Kashmir, 190005
About this study
Official title: Triple-Zero Retrograde Intrarenal Surgery (TZ-RIRS) Versus Conventional Retrograde Intrarenal Surgery (C-RIRS): Development and Internal Validation of the Novel TZ-STONE Feasibility Score
This study evaluates a new minimally invasive surgical technique for treating kidney stones called Triple-Zero Retrograde Intrarenal Surgery (TZ-RIRS).
Traditionally, RIRS is performed using three standard tools: X-ray guidance (fluoroscopy), a plastic tube to keep the ureter open (ureteral access sheath or UAS), and a stent placed before surgery to widen the ureter. While effective, these tools expose patients to radiation, can cause ureteral injuries, and require an extra procedure for the preoperative stent.
Read more
The "Triple-Zero" approach aims to eliminate all three: zero fluoroscopy, zero UAS, and zero preoperative stents. Because this technique is technically demanding, the researchers also developed a new tool called the "TZ-STONE score." This score uses five pre-operative factors (stone size, location, blockage, number of stones, and stone density) to predict which patients are the best candidates for this simplified surgery.
The study compares the safety and success rates of patients who underwent the Triple-Zero approach with those who had conventional RIRS. The researchers aim to see if the Triple-Zero approach achieves similar stone-free rates while reducing radiation exposure, minimizing ureteral injuries, and avoiding the need for a preoperative stent.
Read the detailed description
Retrograde intrarenal surgery (RIRS) is a standard treatment for renal stones. Conventional RIRS (C-RIRS) traditionally involves fluoroscopic guidance, the use of a ureteral access sheath (UAS), and routine preoperative double-J stenting. However, the stochastic risks of ionizing radiation, potential UAS-related ureteral injuries, and the morbidity associated with preoperative stenting have prompted a re-evaluation of these standard adjuncts. The convergence of evidence supporting fluoroscopy-free, sheathless, and stent-free techniques has led to the concept of Triple-Zero RIRS (TZ-RIRS).
This study is a single-center observational cohort analysis. It includes a prospective cohort of 312 consecutive adult patients who underwent TZ-RIRS (January 2023 - December 2025) and a retrospective cohort of 376 patients who underwent C-RIRS (January 2020 - December 2022). To minimize selection bias and control for era effects, 1:1 propensity score matching was performed, yielding a balanced analytical cohort of 250 patients per group.
The primary objective was to develop and internally validate the TZ-STONE score, a novel 10-point pre-operative feasibility tool designed to predict complete TZ-RIRS success (defined as the completion of surgery without intraoperative fluoroscopy, without UAS placement, and without a preoperative stent). The score is derived from five variables: Stone size, Topography, Obstruction (SFU hydronephrosis grade), Number of stones, and Estimated density (HU). The score was developed in a 70% training subset (n=218) and internally validated in a 30% validation subset (n=94).
Secondary objectives included comparing the clinical outcomes between the TZ-RIRS and C-RIRS groups. All procedures utilized an Olympus URF-V2R digital flexible ureteroscope and a 30-watt Karl Storz Holmium:YAG laser. In the TZ-RIRS group, a no-touch direct-vision technique was utilized, along with a modified T-tilt patient position and high-frequency laser dusting. A postoperative stent was placed in all patients in both cohorts.
Outcomes assessed include discrimination (AUC), calibration, and clinical utility (decision curve analysis) of the TZ-STONE score. Clinical outcomes evaluated include stone-free rates at three thresholds (zero fragments, ≤2mm, ≤4mm at 3 months), operative time, fluoroscopy time, Clavien-Dindo complications, and reintervention rates.
- Being tested
- Triple-Zero Retrograde Intrarenal Surgery, Conventional Retrograde Intrarenal Surgery
- Keywords
- Retrograde Intrarenal Surgery, RIRS, Fluoroscopy-Free, Sheathless, TZ-STONE Score, Urolithiasis, Kidney Stones
- Medical subject headings
- Kidney Calculi, Nephrolithiasis, Urolithiasis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Triple-Zero Retrograde Intrarenal SurgeryProcedure or surgery
Also called Triple Zero RIRS, TZ-RIRS, Fluoroscopy-free RIRS
A fluoroscopy-free, sheathless RIRS technique performed using an Olympus URF-V2R digital flexible ureteroscope and a 30-watt Karl Storz Holmium:YAG laser, without preoperative stenting.
Conventional Retrograde Intrarenal SurgeryProcedure or surgery
Also called C-RIRS, Conventional RIRS
Standard RIRS utilizing intraoperative fluoroscopy, placement of a 9.5/11.5 Fr ureteral access sheath (UAS), and a preoperative double-J stent.
| Study group | Role | What they receive |
|---|---|---|
| TZ-RIRS Cohort | Patients who underwent Triple-Zero Retrograde Intrarenal Surgery (TZ-RIRS), defined as zero fluoroscopy, zero ureteral access sheath (UAS), and zero preoperative stenting Receives: Procedure: Triple-Zero Retrograde Intrarenal Surgery | |
| C-RIRS Cohort | Patients who underwent conventional retrograde intrarenal surgery (C-RIRS) utilizing fluoroscopy, a ureteral access sheath (UAS), and routine preoperative stenting Receives: Procedure: Conventional Retrograde Intrarenal Surgery |
What is being measured
The primary outcome is the main question the study is designed to answer.
Complete TZ-RIRS Success
Completion of the surgical procedure without intraoperative fluoroscopy, without rescue ureteral access sheath (UAS) placement, and without a preoperative stent.
Measured: Intraoperative (during the surgical procedure)
Secondary outcomes (7)
Stone-Free Rate (≤4 mm)
Proportion of patients with no residual stone fragments greater than 4 mm on non-contrast CT.
Measured: 3 months postoperatively
Stone-Free Rate (≤2 mm)
Proportion of patients with no residual stone fragments greater than 2 mm on non-contrast CT.
Measured: 3 months postoperatively
Stone-Free Rate (Zero Fragments)
Proportion of patients with zero residual stone fragments on non-contrast CT
Measured: 3 months postoperatively
Operative Time
Total duration of the surgical procedure in minutes, measured from ureteroscope insertion to completion.
Measured: Intraoperative
Complications
Intraoperative and postoperative complications graded by the Clavien-Dindo classification system.
Measured: Up to 3 months postoperatively
Reintervention Rate
Proportion of patients requiring a secondary surgical intervention (e.g., second RIRS, shockwave lithotripsy, or PCNL).
Measured: Up to 3 months postoperatively
Radiation Exposure
Fluoroscopy time (minutes) and radiation dose (mGy) recorded for patients requiring intraoperative conversion to fluoroscopy, compared with conventional RIRS.
Measured: Intraoperative
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted30 Oct 2026
- Study start1 Jan 2020
- Primary completion31 Dec 2025
- Study completion31 Dec 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Kidney Calculi (or Renal Calculi / Nephrolithiasis)Studies 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
- 688 participants (actual)
Sponsor and investigators
- Lead sponsor
- Government Super Speciality Hospital, Shireen Bagh, Srinagar
- Sponsor type
- Other government
- Responsible party
- Principal investigator, Waseem Ashraf, Government Super Speciality Hospital, Shireen Bagh, Srinagar
- Investigators
- Waseem ASHRAF, MBBS, MS, MCh, Principal investigator, Government Super Speciality Hospital, Shireen Bagh, Srinagar
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07906964
- Sponsor's protocol ID
- IRBGMC-SS/Uro/1879
- Acronym
- TZ-RIRS
- Status last verified
- Oct 2026
- First submitted
- 24 Oct 2026
- Last updated
- 3 Nov 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 3 Nov 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Triple-Zero Retrograde Intrarenal Surgery (TZ-RIRS) Versus Conventional Retrograde Intrarenal Surgery (C-RIRS): Development and Internal Validation of the Novel TZ-STONE Feasibility Score
- ClinicalTrials.gov ID
- NCT07906964
- Acronym / sponsor ID
- TZ-RIRS / IRBGMC-SS/Uro/1879
- Keywords
- Retrograde Intrarenal Surgery, RIRS, Fluoroscopy-Free, Sheathless, TZ-STONE Score, Urolithiasis, Kidney Stones
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 688 participants (actual)
- Lead sponsor
- Government Super Speciality Hospital, Shireen Bagh, SrinagarOther government
- Study start
- 1 Jan 2020 (actual)
- Primary completion
- 31 Dec 2025 (actual)
- Study completion
- 31 Dec 2025 (actual)
- First posted
- 30 Oct 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study evaluates a new minimally invasive surgical technique for treating kidney stones called Triple-Zero Retrograde Intrarenal Surgery (TZ-RIRS).
Traditionally, RIRS is performed using three standard tools: X-ray guidance (fluoroscopy), a plastic tube to keep the ureter open (ureteral access sheath or UAS), and a stent placed before surgery to widen the ureter. While effective, these tools expose patients to radiation, can cause ureteral injuries, and require an extra procedure for the preoperative stent.
The "Triple-Zero" approach aims to eliminate all three: zero fluoroscopy, zero UAS, and zero preoperative stents. Because this technique is technically demanding, the researchers also developed a new tool called the "TZ-STONE score." This score uses five pre-operative factors (stone size, location, blockage, number of stones, and stone density) to predict which patients are the best candidates for this simplified surgery.
The study compares the safety and success rates of patients who underwent the Triple-Zero approach with those who had conventional RIRS. The researchers aim to see if the Triple-Zero approach achieves similar stone-free rates while reducing radiation exposure, minimizing ureteral injuries, and avoiding the need for a preoperative stent.
Detailed description
Retrograde intrarenal surgery (RIRS) is a standard treatment for renal stones. Conventional RIRS (C-RIRS) traditionally involves fluoroscopic guidance, the use of a ureteral access sheath (UAS), and routine preoperative double-J stenting. However, the stochastic risks of ionizing radiation, potential UAS-related ureteral injuries, and the morbidity associated with preoperative stenting have prompted a re-evaluation of these standard adjuncts. The convergence of evidence supporting fluoroscopy-free, sheathless, and stent-free techniques has led to the concept of Triple-Zero RIRS (TZ-RIRS).
This study is a single-center observational cohort analysis. It includes a prospective cohort of 312 consecutive adult patients who underwent TZ-RIRS (January 2023 - December 2025) and a retrospective cohort of 376 patients who underwent C-RIRS (January 2020 - December 2022). To minimize selection bias and control for era effects, 1:1 propensity score matching was performed, yielding a balanced analytical cohort of 250 patients per group.
The primary objective was to develop and internally validate the TZ-STONE score, a novel 10-point pre-operative feasibility tool designed to predict complete TZ-RIRS success (defined as the completion of surgery without intraoperative fluoroscopy, without UAS placement, and without a preoperative stent). The score is derived from five variables: Stone size, Topography, Obstruction (SFU hydronephrosis grade), Number of stones, and Estimated density (HU). The score was developed in a 70% training subset (n=218) and internally validated in a 30% validation subset (n=94).
Secondary objectives included comparing the clinical outcomes between the TZ-RIRS and C-RIRS groups. All procedures utilized an Olympus URF-V2R digital flexible ureteroscope and a 30-watt Karl Storz Holmium:YAG laser. In the TZ-RIRS group, a no-touch direct-vision technique was utilized, along with a modified T-tilt patient position and high-frequency laser dusting. A postoperative stent was placed in all patients in both cohorts.
Outcomes assessed include discrimination (AUC), calibration, and clinical utility (decision curve analysis) of the TZ-STONE score. Clinical outcomes evaluated include stone-free rates at three thresholds (zero fragments, ≤2mm, ≤4mm at 3 months), operative time, fluoroscopy time, Clavien-Dindo complications, and reintervention rates.
Study design
- Observational model
- Cohort
- Time perspective
- Retrospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| TZ-RIRS Cohort | – | Procedure: Triple-Zero Retrograde Intrarenal SurgeryPatients who underwent Triple-Zero Retrograde Intrarenal Surgery (TZ-RIRS), defined as zero fluoroscopy, zero ureteral access sheath (UAS), and zero preoperative stenting |
| C-RIRS Cohort | – | Procedure: Conventional Retrograde Intrarenal SurgeryPatients who underwent conventional retrograde intrarenal surgery (C-RIRS) utilizing fluoroscopy, a ureteral access sheath (UAS), and routine preoperative stenting |
Who may qualify
- Ages
- 18 to 100 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Adult patients (≥18 years) with unilateral renal stones who were scheduled to undergo retrograde intrarenal surgery. The study included a prospective cohort of patients treated with the Triple-Zero technique and a retrospective cohort treated with conventional RIRS. Patients with complex anatomy, active infection, or those requiring preoperative stenting were excluded.
Key inclusion criteria (0 listed)
Key exclusion criteria (8 listed)
- Pregnancy
- Active urinary tract infection at the time of RIRS
- Ureteral stricture or concomitant ureteral stone not resolved
- Staghorn or partial staghorn calculi
- Multiple stones exceeding the size criteria
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Triple-Zero Retrograde Intrarenal SurgeryAlso: Triple Zero RIRS, TZ-RIRS, Fluoroscopy-free RIRSA fluoroscopy-free, sheathless RIRS technique performed using an Olympus URF-V2R digital flexible ureteroscope and a 30-watt Karl Storz Holmium:YAG laser, without preoperative stenting. | Procedure or surgery | TZ-RIRS Cohort |
| Conventional Retrograde Intrarenal SurgeryAlso: C-RIRS, Conventional RIRSStandard RIRS utilizing intraoperative fluoroscopy, placement of a 9.5/11.5 Fr ureteral access sheath (UAS), and a preoperative double-J stent. | Procedure or surgery | C-RIRS Cohort |
Primary outcome
Complete TZ-RIRS Success
Time frame: Intraoperative (during the surgical procedure)
Completion of the surgical procedure without intraoperative fluoroscopy, without rescue ureteral access sheath (UAS) placement, and without a preoperative stent.
7 secondary outcomes
Stone-Free Rate (≤4 mm)
Time frame: 3 months postoperatively
Stone-Free Rate (≤2 mm)
Time frame: 3 months postoperatively
Stone-Free Rate (Zero Fragments)
Time frame: 3 months postoperatively
Operative Time
Time frame: Intraoperative
Complications
Time frame: Up to 3 months postoperatively
Reintervention Rate
Time frame: Up to 3 months postoperatively
Radiation Exposure
Time frame: Intraoperative
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 3 Nov 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Waseem ASHRAF, MBBS, MS, MCh principal investigator
Government Super Speciality Hospital, Shireen Bagh, Srinagar
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Kidney Calculi (or Renal Calculi / Nephrolithiasis) and Renal Calculi, run by Government Super Speciality Hospital, Shireen Bagh, Srinagar at 1 site in India.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 0 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 3 Nov 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in India. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Complete TZ-RIRS Success (time frame: Intraoperative (during the surgical procedure)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 3 Nov 2026.