Ultrathin flexible endoscopes for ureteroscopy. A preliminary experimental and clinical study

Recent advances in fiberoptic technology have resulted in the development of endoscopes with an outer diameter of less than 6 F, including an irrigating or working channel. After preliminary testing of these ultrathin fiberscopes for ureteroscopy on 6 pigs, 17 patients were examined during routine retrograde pyelography. Prototypes of flexible endoscopes without an actively deflectable tip and an outer diameter of 5.5 F (= 1.8 mm) and a 1.5 F (= 0.5 mm) channel were used. Fine-needle aspiration cytology was obtained through the channel. The feasibility, performance and benefits of ureteroscopy with ultrathin, flexible endoscopes were evaluated. At present the lack of maneuverability and the fragility of the fiberscopes limit this method. Yet its routine clinical use, in addition to retrograde ureteropyelography under local anesthesia, shows great promise.