Are new-generation flexible ureteroscopes better than their predecessors?

OBJECTIVE: To compare two newly designed flexible ureteroscopes with their respective predecessors, to determine whether design advances have overcome the limitation of tip deflection, which may interfere with diagnosis and treatment of lower pole renal pathology. MATERIALS AND METHODS: Two new-generation flexible ureteroscopes, the DUR-8 Elite (ACMI, Southborough, MA, USA) and 11278AU (Karl Storz Endoscopy, Culver City, CA, USA) were compared with their previous models, the ACMI DUR-8 and the Storz 11274AAU. Active tip deflection and irrigation flow rates with and without various endoscopic tools were assessed. Specifications, purchase prices and repair costs were obtained from each manufacturer. The field of view and screen image size of each ureteroscope were also compared. RESULTS: The ACMI DUR-8 Elite and the Storz 11278AU had improvements of 79° and 144°, respectively, from their respective older models. Although the tip deflection of all ureteroscopes was compromised by inserting different endoscopic tools, these new instruments were less affected. With a 3 F basket inside the working channel, the ACMI DUR-8 Elite and the Storz 11278AU had only 0.7% and 2.8% loss of upward tip deflection, compared with their older models, at 9.6% and 5.0%, respectively. However, the flow rates of these new instruments were decreased. CONCLUSION: The new flexible ureteroscopes have significantly better active tip deflection than previous models, both with and without endoscopic instrumentation inserted. However, improved flexibility is at the expense of decreased flow rates and higher purchase costs.