Flexible Ureteroscopy With a Flexible and Navigable Suction Ureteral Access Sheath Versus Mini-Percutaneous Nephrolithotomy for 1-2 cm Lower Pole Kidney Stones

Last updated: September 5, 2025
Sponsor: The First Affiliated Hospital of Guangzhou Medical University
Overall Status: Active - Recruiting

Phase

N/A

Condition

Kidney Stones

Treatment

Flexible ureteroscopy with FANS

Mini-percutaneous nephrolithotomy (mini-PCNL)

Clinical Study ID

NCT07159035
ES-2025-181
  • Ages 18-75
  • All Genders

Study Summary

This study, known as the FLAME Trial (Flexible ureteroscopy for Lower pole stones And Mini-pErcutaneous nephrolithotomy), is an international, multicenter, randomized, non-inferiority trial. It aims to compare the effectiveness and safety of flexible ureteroscopy using a flexible and navigable suction ureteral access sheath (FANS) versus mini-percutaneous nephrolithotomy (mini-PCNL) in the treatment of 1-2 cm lower pole kidney stones.

A total of 640 eligible adult patients will be enrolled across 20 high-volume urology centers in China, Russia, Turkey, and India. Participants will be randomly assigned to undergo either FANS-assisted flexible ureteroscopy or mini-PCNL. The primary outcome is the immediate stone-free rate (SFR) assessed by non-contrast CT within 72 hours after surgery. Secondary outcomes include SFR at 1 month, operative time, pain score, length of hospital stay, complication rates, and changes in health-related quality of life.

The goal of this trial is to determine whether the less invasive FANS-assisted approach is non-inferior to mini-PCNL in terms of efficacy, while potentially offering advantages in postoperative recovery and safety.

Eligibility Criteria

Inclusion

Inclusion Criteria:

  1. Adults aged 18-75 years;

  2. American Society of Anesthesiology (ASA) score 1-3;

  3. Lower pole renal stones-single or multiple-with a maximal diameter of 1-2 cmconfirmed by CT;

  4. Ability to provide written informed consent and adhere to trial requirements.

Exclusion

Exclusion Criteria:

  1. Significant urinary tract anatomical anomalies (e.g. horseshoe kidney, ilealconduit);

  2. Stones located within a calyceal diverticulum;

  3. History of open nephrolithotomy or ureterolithomy (due to resultant intrarenalanatomical distortion);

  4. Absolute contraindications to either FANS-f-URS or mini-PCNL, including:

  • Uncorrectable coagulopathy;

  • Active, uncontrolled urinary tract infection;

  • Severe cardiopulmonary disease precluding safe general anesthesia (e.g.decompensated heart failure, refractory COPD);

  • Pregnancy;

  • Inability to tolerate lithotomy or prone positioning;

  1. Inability to understand or complete trial documentation.

Study Design

Total Participants: 640
Treatment Group(s): 2
Primary Treatment: Flexible ureteroscopy with FANS
Phase:
Study Start date:
August 28, 2025
Estimated Completion Date:
March 31, 2026

Study Description

The FLAME Trial (Flexible ureteroscopy for Lower pole stones And Mini-pErcutaneous nephrolithotomy) is an international, multicenter, prospective, randomized, controlled, non-inferiority study that aims to evaluate the safety and efficacy of flexible ureteroscopy assisted by a Flexible and Navigable Suction Ureteral Access Sheath (FANS) compared with mini-percutaneous nephrolithotomy (mini-PCNL) in the treatment of 1-2 cm lower pole renal stones.

This trial will enroll 640 patients from 20 urology centers with substantial experience in endoscopic stone surgery, including hospitals in China, Russia, Turkey, and India. Eligible participants will be randomly assigned in a 1:1 ratio to either the FANS-assisted flexible ureteroscopy group or the mini-PCNL group. All patients will undergo preoperative imaging, intraoperative standardization, and postoperative follow-up according to the study protocol.

The primary endpoint is the stone-free rate (SFR) within 72 hours postoperatively, evaluated by non-contrast-enhanced computed tomography (NCCT). Secondary endpoints include SFR at 1 month, operative time, length of hospital stay, postoperative pain (measured by VAS score), complication rates (graded by Clavien-Dindo classification), changes in renal function, and health-related quality of life (HRQoL).

The FANS, developed to improve irrigation control and active stone fragment suction during flexible ureteroscopy, may provide better visualization, reduce intrarenal pressure, and shorten operative time. By directly comparing FANS-assisted fURS with mini-PCNL, the trial seeks to determine whether a less invasive method can achieve comparable outcomes in terms of stone clearance and complication rates.

Connect with a study center

  • The First Affiliated Hospital of Guangzhou Medical University

    Guangzhou 1809858, Guangdong 1809935 510230
    China

    Active - Recruiting

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