Preventing stone retropulsion during intracorporeal lithotripsy.

Several studies of ureteroscopic treatment for ureteral stones have reported that most stone clearance failures can be attributed to stone fragment retropulsion. Stone retropulsion can result in increased operative time and cost-resulting from the need to change from the semi-rigid ureteroscope to a flexible instrument to chase migrated calculi-and additional procedures to treat residual migrated fragments are often required. The degree of migration depends mainly on the energy source used for lithotripsy; pneumatic and electrohydraulic lithotripters are associated with a greater degree of retropulsion than lasers. Different stone-trapping strategies and devices have been developed to minimize stone migration. Novel devices include the Lithovac(®) suction device, the Passport(™) balloon, the Stone Cone(™), the PercSys Accordion(®), the NTrap(®), and stone baskets such as the LithoCatch(™), the Parachute(™), and the Escape(®). Some authors have also reported on the use of lubricating jelly and BackStop(®) gel (a reverse thermosensitive polymeric plug); these devices are instilled proximal to the stone prior to the application of kinetic energy in order to prevent retrograde stone migration.