title: A new era: performance and limitations of the latest models of flexible ureteroscopes.
abstract: OBJECTIVE
  To comparatively study 3 of the latest models of flexible ureteroscopes using both subjective and objective parameters.
  
  
  METHODS
  Three models of flexible ureteroscopes (Karl Storz Flex-Xc, Olympus URF-Vo, and Wolf Cobra) were evaluated during 90 procedures. For each model, 20 procedures were therapeutic for pyelocaliceal lithiasis and 10 were diagnostic. The maneuverability and visibility were scored and compared, and the irrigation flow and maximal deflection were measured in an ex vivo setting, with an empty working channel and with accessory instruments in place. Instrument durability was also reviewed.
  
  
  RESULTS
  All models demonstrated good maneuverability, with a slight advantage for the Flex-Xc. During the diagnostic procedures, failure to access the entire pyelocaliceal system occurred in 2 cases with the URF-Vo, both because of a thin caliceal infundibulum, and in 1 case with the Cobra, because of complex caliceal architecture. Regarding visibility, although the performance of the digital models was relatively similar, the fiberoptic Cobra achieved a lower score. Loss of deflection and irrigation when using the various ancillary instruments was similar for all 3 endoscopes, but the Cobra offered supplementary flow through a secondary channel. The mean deflection loss was 5% for the URF-Vo, 9% for the Flex-Xc, and 10% for the Cobra. The visual quality of the 2 digital models remained unchanged during the study; however, in the fiberoptic ureteroscope, 58 optic fibers were broken.
  
  
  CONCLUSIONS
  The latest models of flexible ureteroscopes have proved to be effective instruments for upper urinary tract endoscopic interventions. There is still room for improvement, already made possible by the technological advances.
authors.affiliation: Department of Urology, Saint John Emergency Clinical Hospital, Bucharest, Romania. Electronic address: razvanmultescu@yahoo.com.
authors.forename: Razvan
authors.initials: R
authors.lastname: Multescu
authors.forename: Bogdan
authors.initials: B
authors.lastname: Geavlete
authors.forename: Petrisor
authors.initials: P
authors.lastname: Geavlete
mesh_terms: D004867:Equipment Design; D005336:Fiber Optic Technology; D006801:Humans; D007669:Kidney Calculi / Q000601:surgery; D008422:Materials Testing; D020709:Ureteroscopes / Q000639:trends