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

NCT07159035 | Recruiting

• 1 other identifier: ES-2025-181
• Study Type: interventional
• Target: 640
• Locations: 1 country
• Sites: 1

Brief 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.

Conditions

Kidney Stones

Keywords

kidney stones; FANS; PCNL; RIRS; flexible ureteroscopy

Outcome Measures

Primary Outcomes (1)

• Immediate Stone-Free Rate (SFR)

  Stone-free status will be evaluated using non-contrast-enhanced computed tomography (NCCT) performed within 72 hours after surgery. Stone-free is defined as the absence of residual stone fragments or presence of clinically insignificant fragments ≤2 mm.

  72 hours after surgery

Secondary Outcomes (6)

• Final Stone-Free Rate (SFR) at 1 Month

  1 month after surgery

• Operative Time

  Intraoperative

• Postoperative Pain Level

  Within 24 hours after surgery.

• Length of Hospital Stay

  From the day of surgery until the day of discharge, assessed up to 30 days postoperatively.

• Complication Rate Within 1 Month

  1 month after surgery.

Study Arms (2)

FANS-fURS Group

EXPERIMENTAL

Patients assigned to this group will undergo flexible ureteroscopy with FANS (Flexible endoscopy-Assisted Negative-pressure Suction Sheath). The FANS facilitates direct stone visualization, fragmentation, suction, and removal under controlled pressure conditions.

Procedure: Flexible ureteroscopy with FANS

mini-PCNL Group

ACTIVE COMPARATOR

Patients in this group will receive mini-percutaneous nephrolithotomy (mini-PCNL) via less than 20 Fr percutaneous tracts.

Procedure: Mini-percutaneous nephrolithotomy (mini-PCNL)

Interventions

Flexible ureteroscopy with FANS PROCEDURE

The FANS with negative-pressure suction, enhancing intrarenal pressure control and fragment evacuation during flexible ureteroscopy.

FANS-fURS Group

Mini-percutaneous nephrolithotomy (mini-PCNL) PROCEDURE

Mini-PCNL is performed under general anesthesia with less than 20 Fr access tract, using rigid nephroscopy and stone fragmentation under direct visualization. Postoperative drainage is provided via nephrostomy or ureteral stent as per protocol.

mini-PCNL Group

Eligibility Criteria

• Age: 18 Years - 75 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Adults aged 18-75 years;
• American Society of Anesthesiology (ASA) score 1-3;
• Lower pole renal stones-single or multiple-with a maximal diameter of 1-2 cm confirmed by CT;
• Ability to provide written informed consent and adhere to trial requirements.

You may not qualify if:

• Significant urinary tract anatomical anomalies (e.g. horseshoe kidney, ileal conduit);
• Stones located within a calyceal diverticulum;
• History of open nephrolithotomy or ureterolithomy (due to resultant intrarenal anatomical distortion);
• 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;
• Inability to understand or complete trial documentation.

Sponsors & Collaborators

• The First Affiliated Hospital of Guangzhou Medical University: lead
• Shengjing Hospital: collaborator
• The Third Xiangya Hospital of Central South University: collaborator
• Saint Petersburg State University Hospital: collaborator
• Fortune Urology Clinic: collaborator
• Zhongda Hospital: collaborator
• Tongji Hospital: collaborator
• The First Affiliated Hospital Hengyang Medical School: collaborator
• First Affiliated Hospital of Ningbo University: collaborator
• The Sixth Affiliated Hospital of Guangzhou Medical University: collaborator
• The First Affiliated Hospital of Xiamen University: collaborator
• Dehong People's Hospital: collaborator
• People's Hospital of Nanhai District, Foshan: collaborator
• Huadu District People's Hospital of Guangzhou: collaborator
• Jiangmen Central Hospital: collaborator
• Baoshan No.2 People's Hospital: collaborator
• Guizhou Provincial People's Hospital: collaborator
• Xinhua Hospital, Shanghai Jiao Tong University School of Medicine: collaborator
• Tianjin Medical University Second Hospital: collaborator
• Ankara University: collaborator

Study Sites (1)

The First Affiliated Hospital of Guangzhou Medical University

Guangzhou, Guangdong, 510230, China

RECRUITING

Related Publications (2)

• Skolarikos A, Geraghty R, Somani B, Tailly T, Jung H, Neisius A, Petrik A, Kamphuis GM, Davis N, Bezuidenhout C, Lardas M, Gambaro G, Sayer JA, Lombardo R, Tzelves L. European Association of Urology Guidelines on the Diagnosis and Treatment of Urolithiasis. Eur Urol. 2025 Jul;88(1):64-75. doi: 10.1016/j.eururo.2025.03.011. Epub 2025 Apr 22.

  PMID: 40268592 BACKGROUND

• Zhu W, Zhong J, Wang K, Yin G, Leung CH, Gadzhiev N, Gokce MI, Kalathia J, Gauhar V, Zhang G, Wu G, Li M, Fang L, Zeng S, Bai P, Li J, Zhao Z, Xi M, Mai X, Duan X, Jiang K, Cao J, Meng X, Liu S, Aloyan A, Yuan P, Zhu X, Huang T, Xing J, Du J, Wu W, Ma J, Zhong W, Zhao Z, Liu Y, Ng CF, de la Rosette J, Somani B, Qi S, Zeng G, Yuen SKK. Flexible ureteroscopy with a flexible and navigable suction ureteral access sheath versus mini-percutaneous nephrolithotomy for 1-2 cm lower pole renal stones: Protocol for an international, multicentre, randomized non-inferiority trial (FLAME trial). BJUI Compass. 2025 Nov 29;6(12):e70114. doi: 10.1002/bco2.70114. eCollection 2025 Dec.

  PMID: 41323963 DERIVED

MeSH Terms

Conditions

Kidney Calculi

Condition Hierarchy (Ancestors)

Nephrolithiasis; Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urogenital Diseases; Urolithiasis; Urinary Calculi; Male Urogenital Diseases; Calculi; Pathological Conditions, Anatomical; Pathological Conditions, Signs and Symptoms

Central Study Contacts

Wei Zhu, Ph.D.

CONTACT

+8613622754991; doczw1989@126.com

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: INVESTIGATOR, OUTCOMES ASSESSOR
• Masking Details: Blinding of participants and surgeons is not feasible due to the obvious procedural differences between flexible ureteroscopy with FANS and mini-percutaneous nephrolithotomy. However, radiologists assessing postoperative CT scans will be blinded to treatment allocation. Clinical follow-up assessments will be performed by independent investigators who did not participate in the surgeries. Statistical analysis will also be conducted in a blinded manner, with group assignments concealed from the analyst until data interpretation is complete.
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Vice-president

Model Details: Participants will be randomized in a 1:1 ratio to undergo either FANS-assisted flexible ureteroscopy or mini-percutaneous nephrolithotomy for the treatment of 1-2 cm lower pole renal stones. This is a multicenter, international, randomized, non-inferiority trial.

Study Record Dates

• First Submitted: August 28, 2025
• First Posted: September 8, 2025
• Study Start: August 28, 2025
• Primary Completion: February 28, 2026
• Study Completion: March 31, 2026
• Last Updated: September 8, 2025

Record last verified: 2025-09

Data Sharing

• IPD Sharing: Will not share

Locations

CN (1)