Conventional fiberoptic flexible ureteroscope versus fourth generation digital flexible ureteroscope: a critical...

Development of flexible renoureteroscopy had a significant impact on the diagnosis and management of upper urinary tract pathology. The aim of our study was to compare the performances of a fiberoptic flexible ureteroscope (FFU) with those of a digital flexible ureteroscope (DFU).

We compared the maneuverability, visibility, and fragility of a Storz 11274AA FFU and of an Olympus URF-Vo DFU. In 44 diagnostic retrograde procedures (22 with FFU and 22 with DFU), the maneuverability and visibility were evaluated with a score ranging from 1 to 5. The success of the inferior calix approach, maximal deflection, irrigation flow, and the endoscopes' fatigability were also compared.

FFU and DFU received mean scores of 3.64 vs 4.27 for maneuverability and 3.27 vs 4.68 for visibility. In four cases, acute infundibulopelvic angle and long infundibulum prevented the inferior calix approach with FFU. In two cases, the approach of the narrow infundibulum was impossible using DFU. The normal/pressure irrigation flow through FFU and DFU was 54/144 vs 60/150 mL/min with an empty working channel, decreasing to almost 0 mL/min with 3F instruments inserted. The maximal deflection loss of FFU and DFU ranged between 8% to 50.6% vs 0% to 21.1%, depending on the accessory instrument inserted through the working channel. After 22 procedures, the deflection loss was 10 degrees for the FFU and 0 degrees for the DFU.

DFU proved to have superior maneuverability and visibility, which may translate into improved performances. The larger tip of the DFU may decrease its accessibility, especially in narrow segments of the upper urinary tract.