title: Does failure to visualize the ureter distal to an impacted calculus constitute an impediment to successful lithotripsy?
abstract: BACKGROUND
  A severe degree of ureteral obstruction is viewed as a predictor of poor outcome in shockwave lithotripsy (SWL). Impacted stones are often considered a contraindication to in-situ SWL.
  
  
  METHODS
  Impaction in our study was defined as failure to visualize the ureter distal to the calculus with proximal hold-up of contrast for as long as 3 hours on an intravenous urogram (IVU). We evaluated 30 patients with impacted ureteral calculi, who were compared with a second unimpacted group matched for stone size and stone location. The calculi were reorganized into < or =10-mm and >10-mm groups. The results were compared in terms of clearance rates, number of shockwaves, number of sessions, and number of days between the start of SWL and clearance.
  
  
  RESULTS
  Between January 1998 and December 2001, 30 impacted stones were treated with lithotripsy. Complete clearance rates in the impacted as well as the non-impacted group were 76.7%. There was no statistical difference in the number of shockwaves, sessions, or time to clearance. The results were poorer in lower-ureteral than upper-ureteral calculi, but this difference did not reach statistical significance. However, the differences between the < or =10-mm and >10-mm stones were statistically significant.
  
  
  CONCLUSIONS
  Impaction on an IVU does not affect the results of lithotripsy.
authors.affiliation: Department of Urology, Christian Medical College and Hospital, Vellore, Tamil Nadu, India.
authors.forename: M
authors.initials: M
authors.lastname: Sinha
authors.forename: N S
authors.initials: NS
authors.lastname: Kekre
authors.forename: K N
authors.initials: KN
authors.lastname: Chacko
authors.forename: A
authors.initials: A
authors.lastname: Devasia
authors.forename: G
authors.initials: G
authors.lastname: Lionel
authors.forename: A P
authors.initials: AP
authors.lastname: Pandey
authors.forename: G
authors.initials: G
authors.lastname: Gopalakrishnan
mesh_terms: D006801:Humans; D008096:Lithotripsy / Q000379:methods*; D011859:Radiography; D016896:Treatment Outcome; D014514:Ureteral Calculi / Q000000981:diagnostic imaging / Q000628:therapy*