#1492

Effect of Irrigation Flow Rate, UAS Type and Size, and Extraction Method on the Dissolution and Retrieval Efficiency of Medinik® Hydrogel: An Ex Vivo Study

K. Tan¹, C. Castillo¹, R. Arada¹, R. Kalbit¹

¹Philippines

Introduction:

Medinik® is a two-component hydrogel designed to encapsulate and assist in the retrieval of residual stone fragments during retrograde intrarenal surgery (RIRS). The clinical utility of Medinik® relies on its ability to fully dissolve and facilitate the removal of stone fragments, thereby preventing postoperative complications such as ureteral obstruction and renal colic. Several technical parameters—including irrigation flow rate, ureteral access sheath (UAS) type (conventional vs. Flexible and Navigable Suction UAS [FANS]), UAS size, and retrieval method (basket vs. suction)—may influence hydrogel behavior. Prior studies support the role of suction-enabled UAS in reducing intrarenal pressure (IRP) and enhancing stone fragment. Encapsulation-based approaches, such as the glue-clot method, further underscore the potential of hydrogel-based solutions.

Material and methods:

A custom-made, ex vivo, 3D-printed model of the human pelvocalyceal system was constructed using transparent resin to allow direct visualization. Medinik® hydrogel was applied according to the manufacturer’s protocol. A 7.5 Fr flexible ureteroscope was used for all procedures. Two UAS types—conventional and FANS—in sizes 10/12F and 11/13F were evaluated. Irrigation flow rates were set at 30, 50, 80, and 100 mL/min. A negative pressure suction system calibrated to 30 kPa was employed in the FANS and suction trials. The primary endpoint was hydrogel dissolution time. Secondary outcomes included retrieval time, residual hydrogel, and overall removal efficiency. Retrieval was performed using either suction or a stone basket.

Results:

No complete dissolution of Medinik® hydrogel was observed within 25 minutes under any irrigation flow setting. However, faster and more efficient removal was achieved at an irrigation rate of 100 mL/min, particularly when using FANS. Compared to conventional UAS and basket extraction, FANS enabled superior clearance of the hydrogel under direct endoscopic visualization.