Clinical Trial of VISOR vs fURS for Upper Urinary Tract Stone

• Study Background and Rationale

Urolithiasis is a highly prevalent urological disease, ranking first among inpatient admissions in urology departments. It is characterized by high incidence and recurrence rates. In China, the incidence ranges from 1% to 5%, with higher rates in the eastern and southern regions, reaching 5-10% in the south. Approximately 150-200 new cases per 100,000 people require hospitalization each year, with a rising trend establishing China as one of the world's three high-risk regions for stones.

The primary surgical treatments for renal stones are flexible ureteroscopy (fURS) and percutaneous nephrolithotomy (PCNL). fURS, utilizing the natural urinary tract, is minimally invasive with fewer complications but is limited by lower lithotripsy efficiency, making it guideline-recommended for stones <2cm. PCNL, while highly efficient for stones >2cm, carries higher risks, including significant bleeding and potential injury to adjacent organs.

There is a growing trend to use fURS for larger stones (>2cm), yet several challenges remain:

Low Lithotripsy Efficiency: Small working channels limit laser fiber size, requiring dusting, which clouds the visual field.

Difficulty in Stone Retrieval: Incomplete clearance, especially in the lower pole, leads to residual fragments, increasing the risk of obstruction and recurrence.

Uncontrolled Intrarenal Pressure (IRP): Obstruction of the ureteral access sheath (UAS) can cause elevated IRP, leading to fluid absorption and life-threatening urosepsis. Current suction techniques are inefficient at pressure control.

Multiple Procedures: The above issues often necessitate multiple surgeries, increasing patient burden.

While technological advances like high-power lasers and the "dusting" technique have expanded fURS applications, the fundamental problems of fragment clearance and IRP control persist. The novel Vortex Intelligence Stone Optimized Removal System(VIROS) is designed to address these limitations by integrating irrigation-suction, pressure monitoring-regulation, and lithotripsy-evacuation into a single platform. This study aims to rigorously evaluate whether this system can improve stone-free rates while maintaining a safer intraoperative pressure profile compared to standard single-use fURS.

• Study Objectives

Primary Objective: To compare the postoperative immediate stone-free rate (SFR) at 24 hours between the experimental system and the single-use fURS.

Secondary Objectives: To compare the two groups regarding:

SFR at 3 months postoperatively. Intraoperative parameters (ureteroscopy operation time, lithotripsy time, total laser energy).

Safety outcomes (Traxer ureteral injury grade, postoperative complications per Clavien-Dindo classification, postoperative fever rate).

Postoperative pain scores (VAS).

• Study Design

Design: Prospective, randomized, controlled, single-blind (outcome assessor), parallel-group clinical trial.

Sample Size: 100 participants. Randomization: 1:1 allocation to experimental or control group using a computer-generated randomization schedule. Opaque sealed envelopes will be used to conceal allocation until intervention.

Blinding: Due to the nature of the devices, surgeons and patients cannot be blinded. However, radiologists assessing the primary outcome (CT scans for stone clearance) and data analysts will be blinded to group assignment.

• Study Population

Inclusion criteria

Adults (≥18 years) with upper urinary tract stones (cumulative diameter ≤3cm) scheduled for fURS holmium laser lithotripsy, who can provide informed consent.

Exclusion criteria

Key exclusions include need for bilateral surgery, significant hydronephrosis (≥4cm), previous renal/ureteral surgery, active infection/fever, pregnancy, severe comorbidities (ASA≥3), renal anatomical anomalies, coagulation disorders, and concurrent participation in another trial.

• Interventions

Experimental Group: Surgery will be performed using the Vortex-Assisted Stone Removal Ureterorenoscopy System (Double-channel pressure-measuring electronic ureterorenoscope, Model: XY-MU-12-620S) through a 14Fr UAS. The system's integrated suction and pressure monitoring functions will be utilized throughout the procedure.

Control Group: Surgery will be performed using a standard single-use electronic ureterorenoscope (Model: XY-S650A) through a 14Fr UAS, following conventional surgical protocols without the integrated suction/pressure control of the experimental system.

All other surgical, anesthetic, and perioperative care protocols will be identical for both groups.

• Study Procedures and Timeline

Screening (Day -14 to 0): Informed consent, eligibility assessment, collection of baseline demographics and medical history, and pre-operative tests (lab tests, ECG, NCCT).

Treatment (Day 0): Randomized surgery. Intraoperative data (times, laser energy, Traxer grade) and adverse events are recorded.

Post-op 24 Hours: Pain assessment (VAS), temperature monitoring, complication assessment, and NCCT to evaluate the primary outcome (immediate SFR). Blood tests (CRP, IL-6, PCT) are repeated to monitor for infection.

Follow-up 1 (21 ± 7 days): Clinical review, decision on stent removal based on post-op Day 1 CT findings, recording of adverse events and unplanned readmissions.

Follow-up 2 (90 ± 14 days): Final NCCT to determine secondary outcome (3-month SFR), assessment of hydronephrosis, and recording of any late adverse events or re-interventions.

• Outcome Measures

Primary Endpoint: Immediate Stone-Free Rate (SFR), defined as the absence of residual fragments ≥4mm on NCCT within 24 hours post-surgery.

Secondary Endpoints:

SFR at 90 days (residual fragments <4mm). Ureteroscopic operation time (from scope entry to exit). Total lithotripsy time and total laser energy (Joules). Intraoperative ureteral injury (Traxer grading scale, 0-4). Postoperative pain (Visual Analog Scale, 0-10). Incidence of postoperative fever (body temperature ≥38.0°C). Postoperative complication rate and severity (Clavien-Dindo Classification).

• Data Analysis

Statistical analyses will be performed using appropriate software (e.g., SPSS, R). The difference in the primary outcome (immediate SFR) between groups will be analyzed using Chi-square or Fisher's exact test. Continuous variables (e.g., operation time, pain scores) will be compared using Student's t-tests or Mann-Whitney U tests depending on data distribution. A p-value of <0.05 will be considered statistically significant.

Inclusion criteria

• Patients with upper urinary tract stones and a cumulative stone diameter ≤3 cm;
• Patients scheduled to undergo "flexible ureteroscopic holmium laser lithotripsy";
• Age ≥18 years;
• Patients without psychiatric disorders or language dysfunction, capable of understanding the study and providing informed consent.

Exclusion criteria

• Patients requiring bilateral lithotripsy in a single-stage ureteroscopic procedure;
• Ipsilateral hydronephrosis with >4 cm renal pelvic separation;
• Patients with a history of open or laparoscopic renal and/or ureteral surgery;
• Fever (body temperature ≥38°C) due to urinary tract infection or other causes within one week prior to surgery;
• Pregnant women;
• Patients with severe systemic diseases, cardiac diseases, pulmonary insufficiency, or vital organ failure unable to tolerate anesthesia or surgery (ASA score ≥3);
• Patients with anatomical abnormalities such as polycystic kidney, horseshoe kidney, or ectopic kidney;
• Patients with coagulation disorders (e.g., INR >2.0 or platelet count <80×10⁹/L);
• Patients currently participating in other device or drug clinical trials;
• Patients deemed ineligible for the trial by the investigator.