title: Impact of renal anatomy on shock wave lithotripsy outcomes for lower pole kidney stones: results of a prospective multifactorial analysis controlled by computerized tomography.
abstract: OBJECTIVE
  We evaluated which variables impact fragmentation and clearance of lower pole calculi after shock wave lithotripsy.
  
  
  METHODS
  We prospectively evaluated patients undergoing shock wave lithotripsy for a solitary 5 to 20 mm lower pole kidney stone between June 2012 and August 2014. Patient body mass index and abdominal waist circumference were recorded. One radiologist blinded to shock wave lithotripsy outcomes measured stone size, area and density, stone-to-skin distance, infundibular length, width and height, and infundibulopelvic angle based on baseline noncontrast computerized tomography. Fragmentation, success (defined as residual fragments less than 4 mm in asymptomatic patients) and the stone-free rate were evaluated by noncontrast computerized tomography 12 weeks postoperatively. Univariate and multivariate analysis was performed.
  
  
  RESULTS
  A total of 100 patients were enrolled in the study. Mean stone size was 9.1 mm. Overall fragmentation, success and stone-free rates were 76%, 54% and 37%, respectively. On logistic regression body mass index (OR 1.27, 95% CI 1.11-1.49, p = 0.004) and stone density (OR 1.0026, 95% CI 1.0008-1.0046, p = 0.005) significantly impacted fragmentation. Stone size (OR 1.24, 95% CI 1.07-1.48, p = 0.039) and stone density (OR 1.0021, 95% CI 1.0007-1.0037, p = 0.012) impacted the success rate while stone size (OR 1.24, 95% CI 1.04-1.50, p = 0.029), stone density (OR 1.0015, 95% CI 1.0001-1.0032, p = 0.046) and infundibular length (OR 1.1035, 95% CI 1.015-1.217, p = 0.015) impacted the stone-free rate. The best outcomes were found in patients with a body mass index of 30 kg/m(2) or less, stones 10 mm or less and 900 HU or less, and an infundibular length of 25 mm or less. The coexistence of significant unfavorable variables led to a stone-free rate of less than 20%.
  
  
  CONCLUSIONS
  Obese patients with higher than 10 mm density stones (greater than 900 HU) in the lower pole of the kidney with an infundibular length of greater than 25 mm should be discouraged from undergoing shock wave lithotripsy.
authors.affiliation: Division of Urology, Hospital das Clinicas, University of São Paulo Medical School, São Paulo, Brazil; Stevan B. Streem Center for Endourology and Stone Disease, Glickman Urological and Kidney Institute (MM), Cleveland Clinic, Cleveland, Ohio. Electronic address: fabio.torricelli@hotmail.com.
authors.forename: Fabio C M
authors.initials: FC
authors.lastname: Torricelli
authors.affiliation: Division of Urology, Hospital das Clinicas, University of São Paulo Medical School, São Paulo, Brazil; Stevan B. Streem Center for Endourology and Stone Disease, Glickman Urological and Kidney Institute (MM), Cleveland Clinic, Cleveland, Ohio.
authors.forename: Giovanni S
authors.initials: GS
authors.lastname: Marchini
authors.affiliation: Division of Urology, Hospital das Clinicas, University of São Paulo Medical School, São Paulo, Brazil; Stevan B. Streem Center for Endourology and Stone Disease, Glickman Urological and Kidney Institute (MM), Cleveland Clinic, Cleveland, Ohio.
authors.forename: Fernando I
authors.initials: FI
authors.lastname: Yamauchi
authors.affiliation: Division of Urology, Hospital das Clinicas, University of São Paulo Medical School, São Paulo, Brazil; Stevan B. Streem Center for Endourology and Stone Disease, Glickman Urological and Kidney Institute (MM), Cleveland Clinic, Cleveland, Ohio.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Danilovic
authors.affiliation: Division of Urology, Hospital das Clinicas, University of São Paulo Medical School, São Paulo, Brazil; Stevan B. Streem Center for Endourology and Stone Disease, Glickman Urological and Kidney Institute (MM), Cleveland Clinic, Cleveland, Ohio.
authors.forename: Fabio C
authors.initials: FC
authors.lastname: Vicentini
authors.affiliation: Division of Urology, Hospital das Clinicas, University of São Paulo Medical School, São Paulo, Brazil; Stevan B. Streem Center for Endourology and Stone Disease, Glickman Urological and Kidney Institute (MM), Cleveland Clinic, Cleveland, Ohio.
authors.forename: Miguel
authors.initials: M
authors.lastname: Srougi
authors.affiliation: Division of Urology, Hospital das Clinicas, University of São Paulo Medical School, São Paulo, Brazil; Stevan B. Streem Center for Endourology and Stone Disease, Glickman Urological and Kidney Institute (MM), Cleveland Clinic, Cleveland, Ohio.
authors.forename: Manoj
authors.initials: M
authors.lastname: Monga
authors.affiliation: Division of Urology, Hospital das Clinicas, University of São Paulo Medical School, São Paulo, Brazil; Stevan B. Streem Center for Endourology and Stone Disease, Glickman Urological and Kidney Institute (MM), Cleveland Clinic, Cleveland, Ohio.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Mazzucchi
mesh_terms: D006801:Humans; D007668:Kidney / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D007669:Kidney Calculi / Q000000981:diagnostic imaging* / Q000628:therapy*; D008096:Lithotripsy; D015999:Multivariate Analysis; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
keywords: anatomy; kidney; lithotripsy; obesity; tomography; x-ray computed