Improved Functional Deflection with a Dual-Deflection Flexible Ureteroscope

Purpose: To compare the maximal active deflection capabilities of a newly designed dual-deflection ureteroscope with those of a standard flexible ureteroscope. Materials and Methods: The dual-deflection ureteroscope is similar in design to single-deflection ureteroscopes with the addition of a second, more proximal unidirectional deflection point, which is controlled with the index finger on the contralateral side of the instrument. We evaluated the maximal deflection angles achieved with this ureteroscope with no inserted devices as well as with 200-, 365-, and 550-μm laser fibers and a 3F Nitinol wire basket in the working port. We compared these angles with those obtained with the Dur-8 single-deflection ureteroscope. Results: The dual-deflection ureteroscope allowed a superior maximum active deflection angle of 234.3° with an empty working channel compared with only 143° for the standard single-deflection ureteroscope. Instruments in the working channel dampened the active deflection of both ureteroscopes. The average maximum upward angles achievable with the single-deflection ureteroscope with the 200-, 365-, and 550-μm laser fibers and the 3F basket were 115.3°, 92°, 46.6°, and 123.3°, respectively. The average deflection angles with the dual-deflection endoscope deflected at the distal point were similar to those obtained with the single-deflection ureteroscope. In contrast, the average maximum deflection angles obtained with the dual-deflection endoscope deflected at both points with a 200-, 365-, and 550-μm laser fiber and a 3F basket in the working channel were 211°, 183.3°, 109°, and 224°, respectively. The degree of dampening by larger instruments was greater in the single-deflection than the dual-deflection ureteroscope. Conclusions: The double-deflection ureteroscope can achieve superior active deflection compared with a standard ureteroscope. The second active angle allows the use of larger instruments in the working port with a smaller impact on overall deflection. The double-deflection ureteroscope should be beneficial in the management of difficult-to-treat lower-pole renal calculi and may allow some patients who would have required percutaneous nephrolithotomy to undergo ureteroscopic management of their stone disease.