Exaggerated primary endoscope deflection: initial clinical experience with prototype flexible ureteroscopes

OBJECTIVE: To increase the clinical usefulness of the actively deflectable flexible ureteroscope by making sequential changes in design and then using these prototypes clinically; and to develop a clinical series using the optimum prototype and contrast it with an extensive database of patients treated with the traditional flexible ureteroscope. METHODS: A series of prototypic flexible ureteroscopes was developed and used clinically. The active deflection of the prototype ureteroscope was evaluated with and with no accessories in the working channel, and compared with a standard 7.5 F ureteroscope. Clinical data were then accrued and compared with a previously published database. RESULTS: The progression of prototypes led to a final version which incorporated > 300 degrees primary active deflection, shaft miniaturization (8.4 F) and an increase in endoscope shaft stiffness. The prototype flexible ureteroscope had significantly greater active deflection than the standard ureteroscope, especially when working channel accessories were used. In all, 115 endoscopic procedures were carried out, the indications for which included endoscopic lithotripsy for distal calculi (51), treatment of upper tract urothelial carcinoma (27), diagnostic endoscopy (26) and retrograde endopyelotomy (three). No guidewire was required to place the flexible ureteroscope into the upper urinary tract in 27% of patients. Active intramural dilatation for access was only required in 3% of the procedures. All lower pole calyces were accessed with this instrument. CONCLUSIONS: Adding exaggerated deflection is a timely advance in flexible ureteropyeloscopy. This and the other changes in design facilitated complex retrograde endoscopic procedures and increased the therapeutic potential of the instrument.