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-microm
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 degrees with an empty working channel compared with only 143 degrees 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-microm
laser fibers and the 3F basket were 115.3 degrees, 92 degrees, 46.6 degrees, and 123.3 degrees, 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-microm
laser fiber and a 3F basket in the working channel were 211 degrees, 183.3 degrees, 109 degrees, and 224 degrees, 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.