[Ultra-thin, flexible ureteropyeloscopy: a new diagnostic possibility. An animal experiment and clinical pilot study].

Recent advances in fiberoptic technology have resulted in the development of fiberscopes with an outer diameter of less than 6 F and an irrigating or working channel. The feasibility, conditions and benefit of ureteropyeloscopy with ultrathin, flexible endoscopes were evaluated in two sets of investigations: (1) in 6 pigs and (2) in 12 patients during routine retrograde pyelography. Prototypes of flexible endoscopes with a passively deflectable tip, 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 is possible through the channel under endoscopic control. At present, the lack of maneuverability and the fragility of the fiberscopes limit this method. Its use in the clinical routine, in addition to retrograde ureteropyelography, under local anesthesia is of great promise, however.