Ex Vivo Porcine Kidney Model for Evaluating Flow-Pressure Dynamics and Stone Retrieval in Suction-Assisted Retrograde Intrarenal Surgery.

Retrograde intrarenal surgery (RIRS) using a suction ureteral access sheath (UAS) has become an effective approach for renal stone management. However, standardized experimental models capable of simultaneously controlling and evaluating relevant parameters, including irrigation pressure, suction pressure, and the ratio of endoscope-sheath diameter (RESD), remain limited. The aim of this study is to propose an ex vivo porcine kidney model designed to enable controlled and repeatable evaluation of flow-pressure conditions with suction UAS. The protocol utilized fresh cadaveric porcine kidneys placed in a fixed container system, with the suction UAS positioned at the upper pole calyx, and artificial stones mimicking calcium oxalate monohydrate introduced into the collecting system. An automated pressure-control pump system enabled precise regulation of irrigation and suction pressures. Intrarenal pressure (IRP) was continuously recorded for 1 min, and pull-out time (POT) was measured repeatedly under each RESD and pressure setting. The coefficient of variation (CV) and intraclass correlation coefficient (ICC) were calculated to assess measurement variability and reliability. The model demonstrated distinct IRP responses across different RESD and pressure conditions, including values exceeding 40 mmHg. POT measurements varied according to pressure settings, reflecting sensitivity to changes in flow-pressure conditions. CV analysis showed relatively narrow variability across most conditions, while ICC analysis demonstrated moderate reliability for single measurements and high reliability for averaged repeated measurements. Overall, this ex vivo porcine kidney model provides a standardized ex vivo reference for RIRS by presenting objective and reliable repeated measurement data using a suction UAS and a flexible ureteroscope.