title: Stone clearance after extracorporeal shockwave lithotripsy in patients with solitary pure calcium oxalate stones smaller than 1.0 cm in the proximal ureter, with special reference to monohydrate and dihydrate content.
abstract: OBJECTIVE
  The aim of this study was to assess stone-free rates following extracorporeal shockwave lithotripsy (ESWL) of pure calcium oxalate (CaOx) stones in the proximal ureter.
  
  
  METHODS
  The investigators retrospectively examined 53 patients with 5-10 mm pure CaOx stones in the proximal ureter from the medical archives of 593 consecutive patients treated with ESWL. The compositions of calcium oxalate monohydrate (COM) and dihydrate (COD) in a given stone were determined by infrared spectrometry. Stone size, attenuation number and stone-to-skin distance (SSD) were measured using plain radiography and computed tomography (CT). ESWL success was evaluated by stone-free status after the first single session.
  
  
  RESULTS
  On average, calculi were 8.0 × 5.3 mm in size, with an SSD of 11.0 cm. The mean CT attenuation value was 740.1 HU. Attenuation numbers correlated significantly with stone diameter (r = 0.49), but had no correlation with the stone content of COM or COD. A negative correlation was observed between COM and COD content (r = -0.925). With regard to patients' physical characteristics and COM and COD content, no differences were found between study subgroups with stone-free and residual status (n = 38 and 15, respectively). There were also no differences in clinical features between patient subgroups with COM- or COD-predominant stones (n = 22 and 31, respectively).
  
  
  CONCLUSIONS
  The findings indicated that the differences in COM and COD content of CaOx stones had no impact on stone clearance after ESWL and that a favorable stone-free rate of the stones treated with ESWL may be achieved independently of CaOx hydration.
authors.affiliation: Department of Urology, Faculty of Medicine, Yamagata University, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Ichiyanagi
authors.forename: Akira
authors.initials: A
authors.lastname: Nagaoka
authors.forename: Takuji
authors.initials: T
authors.lastname: Izumi
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kawamura
authors.forename: Masaaki
authors.initials: M
authors.lastname: Tsukigi
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Ishii
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ohji
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Kato
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Tomita
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002129:Calcium Oxalate / Q000032:analysis*; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008096:Lithotripsy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012720:Severity of Illness Index; D019265:Spectroscopy, Near-Infrared / Q000379:methods; D014057:Tomography, X-Ray Computed; D014514:Ureteral Calculi / Q000737:chemistry* / Q000000981:diagnostic imaging / Q000601:surgery
chemical_list: D002129:Calcium Oxalate