Regarding flexible ureteroscopes the following is true:
A. They are routinely used in the treatment of patients with lower ureteric stonesAnswer D
Most distal ureteric stones can be accessed with a rigid ureteroscope where surgical treatment is indicated. Flexible ureteroscopes facilitate the treatment of stones in the proximal ureter and pelvicalyceal system of the kidney. On the other hand, for distal ureteric stones flexible ureteroscopes are unwieldy and may easily slip out of the ureteric orifice.
Technological advances over recent years have led to the development of increasingly thin ureteroscopes that also provide exceptionally high resolution images. For example, the Stortz Flex-X® shaft is 8.5 F which tapers to 7.5 F at the tip. A single lever control allows 270° active deflection of the tip in both upwards and downwards directions. The Olympus URF-P5® has a very slender tip that measures only 5.3 F. It has a maximal upward deflection of 180° and downward deflection of 275° to aid access to the lower pole. The working channels for most flexible ureteroscopes are 3.6 F.
The new digital flexible ureteroscope incorporates a distal video sensor and LEDs for illumination and therefore do not rely on fibre optics for light and image transmission. This results in better image quality although the shaft size and tip size are relatively larger. Furthermore, because of this digital ureteroscopes have limited manoeuvrability of the distal tip compared to fibre-optic flexible ureteroscopes. Single-use flexible ureteroscopes have been on the market since 2015, and are made by a number of companies. There are digital single-use ureteroscopes available.