title: Shock wave lithotripsy success for renal stones based on patient and stone computed tomography characteristics.
abstract: OBJECTIVE
  To determine the patient and noncontrast computed tomography (NCCT) stone characteristics that predict either of 2 extracorporeal shock wave lithotripsy (ESWL) outcomes: stone-free (SF) status or ESWL success.
  
  
  METHODS
  The records of 200 consecutive patients with nephrolithiasis treated with ESWL were reviewed. Patient age, sex, stone laterality, body surface area, body mass index, maximal stone dimension, mean stone Hounsfield units (HU), stone Hounsfield density, skin-to-stone distance (SSD), and intrarenal stone location were studied as potential predictors. Patients with no calcifications on postoperative kidneys, ureters, and bladder (KUB) at 6 weeks were defined as SF. ESWL success was defined as SF or remaining stone fragments less than 4 mm.
  
  
  RESULTS
  Intrarenal stone location was found to be the only predictor of SF status. Renal pelvic/ureteropelvic junction (UPJ) stones cleared better than calyceal stones, and upper/middle calyceal stones cleared better than lower calyceal stones. Stone size, mean HU, and location predicted ESWL fragmentation success. Smaller stones and stones with lower mean HU levels were more successfully fragmented. Higher SF and ESWL success rates were found with a shorter SSD among calyceal stones when renal pelvic/UPJ stones were excluded from analysis.
  
  
  CONCLUSIONS
  Stone location is the most important factor in achieving SF status after ESWL. NCCT stone characteristics such as stone size, mean HU, and intrarenal location are important predictors of ESWL success.
authors.affiliation: Department of Urology, Wilford Hall Medical Center, Lackland Air Force Base, Texas 78236, USA. Kyle.weld@lackland.af.mil
authors.forename: Kyle J
authors.initials: KJ
authors.lastname: Weld
authors.forename: Claudio
authors.initials: C
authors.lastname: Montiglio
authors.forename: Michael S
authors.initials: MS
authors.lastname: Morris
authors.forename: Anneke C
authors.initials: AC
authors.lastname: Bush
authors.forename: R Duane
authors.initials: RD
authors.lastname: Cespedes
mesh_terms: D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000000981:diagnostic imaging* / Q000628:therapy*; D008096:Lithotripsy; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome