An observational study in Kidney Calculi (or Renal Calculi / Nephrolithiasis) and Renal Calculi, sponsored by Government Super Speciality Hospital, Shireen Bagh, Srinagar. Completed at 1 site in India. Open to participants aged 18 Years to 100 Years. Per ClinicalTrials.gov, last updated 2026-11-03.
Sponsored by Government Super Speciality Hospital, Shireen Bagh, Srinagar · Observational
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.
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.
509 studies on the registry are indexed under Kidney Calculi; 146 are open to participants now.
This study's enrollment of 688 is above the median of 160 across 96 observational studies indexed under Kidney Calculi.
Browse Kidney Calculi studies →This is the only study on the registry with Government Super Speciality Hospital, Shireen Bagh, Srinagar as lead sponsor.
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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.
Inclusion Criteria:Non-lower calyceal stones ≤15 mm OR lower calyceal stones ≤10 mm (maximum diameter on CT)
Age ≥18 years
Normal renal anatomy (no congenital anomalies, no horseshoe kidney)
Unilateral stone(s)
No prior ipsilateral RIRS within 6 months
(ASA) physical status I-III
No preoperative double-J stent
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Exclusion Criteria:
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)
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The anaesthetists’ scale of health before surgery: I is healthy, II has a mild illness that is under control, III a severe one, IV a severe illness that is a constant threat to life. V and VI are used for the critically ill and for organ donors.
ASA physical status
The anaesthetists’ scale of health before surgery: I is healthy, II has a mild illness that is under control, III a severe one, IV a severe illness that is a constant threat to life. V and VI are used for the critically ill and for organ donors.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Patients who underwent Triple-Zero Retrograde Intrarenal Surgery (TZ-RIRS), defined as zero fluoroscopy, zero ureteral access sheath (UAS), and zero preoperative stenting
Procedure: Triple-Zero Retrograde Intrarenal Surgery
Patients who underwent conventional retrograde intrarenal surgery (C-RIRS) utilizing fluoroscopy, a ureteral access sheath (UAS), and routine preoperative stenting
Procedure: Conventional Retrograde Intrarenal Surgery
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.
Also known as: Triple Zero RIRS, TZ-RIRS, Fluoroscopy-free RIRS
Standard RIRS utilizing intraoperative fluoroscopy, placement of a 9.5/11.5 Fr ureteral access sheath (UAS), and a preoperative double-J stent.
Also known as: C-RIRS, Conventional RIRS
Complete TZ-RIRS Success
Completion of the surgical procedure without intraoperative fluoroscopy, without rescue ureteral access sheath (UAS) placement, and without a preoperative stent.
Time frame: Intraoperative (during the surgical procedure)
Stone-Free Rate (≤4 mm)
Proportion of patients with no residual stone fragments greater than 4 mm on non-contrast CT.
Time frame: 3 months postoperatively
Stone-Free Rate (≤2 mm)
Proportion of patients with no residual stone fragments greater than 2 mm on non-contrast CT.
Time frame: 3 months postoperatively
Stone-Free Rate (Zero Fragments)
Proportion of patients with zero residual stone fragments on non-contrast CT
Time frame: 3 months postoperatively
Operative Time
Total duration of the surgical procedure in minutes, measured from ureteroscope insertion to completion.
Time frame: Intraoperative
Complications
Intraoperative and postoperative complications graded by the Clavien-Dindo classification system.
Time frame: Up to 3 months postoperatively
Reintervention Rate
Proportion of patients requiring a secondary surgical intervention (e.g., second RIRS, shockwave lithotripsy, or PCNL).
Time frame: 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.
Time frame: Intraoperative
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From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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