Development and validation of a novel in vitro porcine model for impacted ureteral stones based on objective pressure gradient assessment.

To establish and validate an isolated model of upper impacted ureteral stone(IUS) in pigs for clinical research on this common disease. Take two sets (4 sides) of urinary system organs from healthy adult pigs. Insert two lumbar spinal anesthesia needles into the renal collecting system and connect them to pressure measurement pipelines and methylene blue solution perfusion pipelines respectively. Make an incision at the upper part of the pig’s ureter and place a certain volume of stones into the ureter. Suture and narrow the ureteral lumen above and below the stones to cause ureteral stenosis above and below the stones. Finally, gradually increase the perfusion pressure of the methylene blue solution. Use a ureteroscope to observe the perfusion pressure when the methylene blue solution passes through the stones to verify whether the model is successful.The appearance shows that the diameters of the upper and lower ureters at the incarcerated site of the ureteral calculi are significantly narrowed. When the perfusion pressures were 31 cm, 42 cm, 48 cm and 59 cm H₂O respectively, Meilan fluid was seen passing beneath the stones. By inserting stones and creating a narrow passage, a successful model of upper IUS in pigs can be established. This method is simple to operate, has a high success rate, and basically conforms to the anatomical and physiological characteristics of upper IUS. It is a relatively practical clinical model for studying upper ureteral strangulated calculi.