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

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.

NCT Number	NCT07159035
Lead Sponsor	The First Affiliated Hospital of Guangzhou Medical University Collaborators: Shengjing Hospital, The Third Xiangya Hospital of Central South University, Saint Petersburg State University Hospital, Fortune Urology Clinic, Zhongda Hospital, Tongji Hospital, The First Affiliated Hospital Hengyang Medical School, First Affiliated Hospital of Ningbo University, The Sixth Affiliated Hospital of Guangzhou Medical University, The First Affiliated Hospital of Xiamen University, Dehong People's Hospital, People's Hospital of Nanhai District, Foshan, Huadu District People's Hospital of Guangzhou, Jiangmen Central Hospital, Yunnan Baoshan Second People's Hospital, Guizhou Provincial People's Hospital, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Tianjin Medical University Second Hospital, Ankara University
Conditions	Kidney Stones
Enrollment	640 participants
Start Date	2025-08-28
Primary Completion	2026-05-01 (estimated)
Study Completion	2026-06-10 (estimated)
Updated on ClinicalTrials.gov	2026-07-07