title: Safety and efficacy of using the stone cone and an entrapment and extraction device in ureteroscopic lithotripsy for ureteric stones.
abstract: OBJECTIVE
  To assess the safety and efficacy of using a stone cone and an entrapment and extraction device (N-Trap®, Cook Urological, Bloomington, IN, USA) to avoid stone retropulsion during ureteroscopic lithotripsy for ureteric stones.
  
  
  METHODS
  This retrospective comparative study included 436 patients treated with ureteroscopic lithotripsy for a single ureteric stone from February 2011 to January 2014. The diagnosis of a stone was confirmed by plain spiral computed tomography in all cases. Patients were divided according to the ureteric occlusion device applied to avoid stone retropulsion during pneumatic lithotripsy into three groups; group 1 (156) had no instruments used, group 2 (140) in whom the stone cone was applied, and group 3 (140) in whom the N-Trap was used. Patient demographics, stone criteria, operative duration and complications, and success rates (complete stone disintegration with no upward migration) were reported and analysed statistically.
  
  
  RESULTS
  The stone was in the lower ureter in >55% of patients in all groups. The mean (SD) of maximum stone length was 9.8 (2.5), 10.4 (2.8) and 9.7 (2.9) in groups 1-3, respectively. The use of the stone cone or N-Trap did not significantly increase the operative duration (P = 0.13) or complication rates (P = 0.67). There was a statistically significant difference (P < 0.001) favouring groups 2 and 3 for retropulsion and success rates, being 83.3% in group 1, 97.1% in group 2 and 95.7% in group 3.
  
  
  CONCLUSIONS
  The stone cone and N-Trap gave high success rates in preventing stone retropulsion during ureteric pneumatic lithotripsy. Both devices caused no increase in operative duration or complications when used cautiously.
authors.affiliation: Zagazig University, Faculty of Medicine, Urology Department, Zagazig, Sharkia, Egypt.
authors.forename: Waleed
authors.initials: W
authors.lastname: Shabana
authors.affiliation: Zagazig University, Faculty of Medicine, Urology Department, Zagazig, Sharkia, Egypt.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Teleb
authors.affiliation: Zagazig University, Faculty of Medicine, Urology Department, Zagazig, Sharkia, Egypt.
authors.forename: Tamer
authors.initials: T
authors.lastname: Dawod
keywords: Lithotripsy; MSL, maximum stone length; Retropulsion; Stone cone; URS, ureteroscopy; Ureteroscopy