Flexible ureteroscopy has advanced modern stone management; however, lower pole renal stones remain a challenge due to suboptimal ureteroscope deflection and navigation using conventional flexible and navigable suction ureteral access sheaths (FANS). The SCULPT trial is designed to assess whether the novel steerable FANS—which enables active controlled deflection—can improve the success rate of lower pole access during flexible ureteroscopy.

This multicentre, prospective, single-blinded, randomised controlled superiority trial will recruit 400 adult patients (aged 18–75 years) with solitary lower pole renal stones ≤2 cm diagnosed by CT from 20 high-volume urological centres in China. Participants will be randomised 1:1 to undergo flexible ureteroscopy with either steerable or conventional FANS. The primary outcome is the success rate of navigating into the lower pole calyx (defined as successful direct stone visualisation, laser lithotripsy and aspiration without adjunct use). Secondary outcomes include immediate and 1 month stone-free rates, operative time, complication profiles (graded by Clavien–Dindo), instrument damage rates, quality-of-life assessments and cost analysis. Statistical analysis will be performed using appropriate tests for continuous and categorical data, with their significance set by prespecified superiority margins.

The study protocol has been designed in accordance with the Declaration of Helsinki and ICH-GCP guidelines. Ethical approval was centrally granted by the Institutional Review Board of The First Affiliated Hospital of Guangzhou Medical University and adopted by all participating centres following local feasibility review. The trial results will be disseminated via peer-reviewed publication and presentation at international conferences.

NCT06898216.