title: Shockwave lithotripsy in patients with horseshoe kidney: determinants of success.
abstract: OBJECTIVE
  Horseshoe kidney (HSK) is the most common renal fusion anomaly, with a prevalence of ∼1 in 400 and an incidence of urolithiasis between 20% and 60%. The role of shock wave lithotripsy (SWL) in patients with HSK remains poorly studied.
  
  
  METHODS
  Data from all patients treated since January 1994 with a known HSK was reviewed. Analysis was restricted to all patients with a minimum follow-up of 2 weeks after SWL. Success was defined as patients who were stone-free or had asymptomatic, clinically insignificant residual fragments ≤ 4 mm.
  
  
  RESULTS
  Data from 41 patients with HSK were analyzed (61 calculi). Mean stone size was 91.3 ± 71.6 mm(2); mean body mass index was 27.1 ± 5.3 kg/m(2). At 3 months, the single-treatment success and stone-free rates were 25.0% and 9.1%, respectively. The overall treatment success rate at 3 months was 63.6%, and the stone-free rate was 39.1%. Little incremental benefit was found for more than two SWL treatments per stone. The auxiliary treatment rate was 72.7%, with an efficiency quotient of 10.5%. On multivariate analysis, stone burden (p = 0.074), other calyceal location (p = 0.026), and body mass index (p = 0.013) were found to be prognostic for SWL success.
  
  
  CONCLUSIONS
  Patients with HSK appear to have lower success and stone-free rates after SWL than patients with normal kidneys. This likely has to do with factors such as greater skin-to-stone distance (particularly for calyceal stones) and restricted urinary drainage. SWL may be offered to patients with a HSK once limitations in stone clearance have been considered.
authors.affiliation: Division of Urology, Department of Surgery, St. Michael's Hospital, University of Toronto, Toronto, Canada.
authors.forename: A Andrew
authors.initials: AA
authors.lastname: Ray
authors.forename: Daniela
authors.initials: D
authors.lastname: Ghiculete
authors.forename: R John
authors.initials: RJ
authors.lastname: D'A Honey
authors.forename: Kenneth T
authors.initials: KT
authors.lastname: Pace
mesh_terms: D003710:Demography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007668:Kidney / Q000002:abnormalities*; D007674:Kidney Diseases / Q000628:therapy*; D008096:Lithotripsy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome