Ureteroscopy for stone treatment using new 270 degrees semiflexible endoscope: in vitro, ex vivo, and clinical application

Abstract

Background and purpose: The use of flexible ureteroscopy for diagnosis and management of upper urinary tract diseases is limited both by loss of maximum active deflection through the inserted working probes and a high frequency of damage with consequent costs. A newly developed ureteroscope (Flex-X, Karl Storz) with a maximized angle of deflection was introduced to overcome these problems. The aim of our study was to compare this new ureteroscope with an established device in vitro, ex vivo, and in a clinical approach.

Materials and methods: Angles of maximum active deflection and maximum irrigation flow were measured for both scopes in vitro with an empty working channel and after introduction of different lithotripsy and stone extraction probes. In addition, the loss of maximum active deflection and broken optical fibers of the scopes were assessed after 100 flexible ureteroscopies in an ex-vivo pig cadaver model. The clinical performance of both ureteroscopes was evaluated in 32 patients for management of lower pole stones.

Results: The new ureteroscope displays highly improved deflection compared with the standard scope; deflection angles as much as 270 degrees with an empty working channel were achieved. Thin probes did not inhibit maximum deflection. Durability in ex vivotrials was high. Only minimal loss of maximum deflection and three broken optical fibers were observed. In clinical usage, a stone-free rate of 100% was achieved after 4 weeks. In three patients, the opening mechanism of a basket did not work with maximum deflection because of high friction.

Conclusion: The new ureterorenoscope facilitates retrograde stone management and might diminish repair intervals. Further development of comparable devices will support flexible ureterorenoscopy as a standard stone management procedure.