Does Failure to Visualize the Ureter Distal to an Impacted Calculus Constitute an Impediment to Successful Lithotripsy?

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. PATIENTS AND 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. CONCLUSION: Impaction on an IVU does not affect the results of lithotripsy.