Efficacy and safety of the Accordion stone-trapping device: in vitro results from an artificial ureterolithotripsy model.

One of the challenges of intracorporeal ureterolithotripsy is undesired stone migration. Stone-trapping devices have been designed to prevent this quite common phenomenon. These devices have to be effective in terms of ureteral obstruction and safe in terms of resistance to the action of commonly used lithotriptors. This work was conducted to evaluate the efficacy and safety of the recently approved Accordion stone-trapping device in vitro. In a rigid, submerged ureteral model with two different diameters (8 and 10 mm), artificial stones were positioned in direct contact with the engaged Accordion device. A defined number of pneumatic pulses of the LithoClast master at different performance levels was applied and the migration distance of the stone was measured after each single pulse. As a control, the same series was repeated without the stone-trapping device. Secondly, the Accordion device was exposed to a previously defined number of pneumatic or Ho:YAG-laser pulses, in direct contact with the lithotripsy probe, up to a total activation time of 2 min. At different time points, the device was controlled for damage and functionality. The mean stone migration distance without the Accordion device was between 39.2 and 52.8 mm and between 37.8 and 75.4 mm in the 8 and 10 mm tubes, respectively. In comparison, the stone or fragment travelling distance with the device was in the 0-2 mm range. This difference was highly significant. Both pneumatic and laser lithotriptor did not affect the functionality of the Accordion device. The Ho:YAG laser causes small perforations of the film without affecting the devices' stability. The Accordion device appears to be highly efficient and safe in vitro. Clinical trials will have to assess its value in endourological practice. Randomised comparative trials comparing different stone-trapping devices are needed.