title: Utility and limitation of cumulative stone diameter in predicting urinary stone burden at flexible ureteroscopy with holmium laser lithotripsy: a single-center experience.
abstract: OBJECTIVE
  To retrospectively assess the clinical utility in ureteroscopy (URS) planning of cumulative stone diameter (CSD), which does not account for stone width or depth, as a predictor of URS outcome and compare it with stone volume.
  
  
  METHODS
  Patients with renal stones treated at a single institute by flexible URS were retrospectively evaluated. To assess the clinical utility of CSD, relationships between stone-free (SF) status and stone burden (CSD and volume) were analyzed using the area under the receiver operating characteristics (AUROC) curve. To identify stone number impact on CSD, the AUROC of CSD divided by stone number was evaluated. Correlation coefficients of CSD and stone volume were also calculated for groups by stone number.
  
  
  RESULTS
  In cases with CSD <20.0 mm, CSD and stone volume revealed equal ability to predict SF status. In cases with CSD ≥20.0 mm, stone volume showed higher predictive ability. The ROC curves for cases with ≥4 stones showed that CSD was less predictive of SF status than stone volume. The correlation coefficients of CSD and stone volume by stone number were 0.922 for 1 stone, 0.900 for 2-3 stones, and 0.661 for ≥4 stones.
  
  
  CONCLUSIONS
  In cases with CSD ≥20.0 mm or ≥4 stones, we should evaluate stone volume for a more predictive stone burden, and pretreatment non-contrast CT seems sufficient. In cases with CSD <20.0 mm or 1-3 stones, CSD was as valid a predictor of preoperative stone burden as stone volume, so preoperative kidney-ureter-bladder (KUB) films may be sufficient.
authors.affiliation: Department of Urology, Ohguchi East General Hospital, Yokohama City, Japan. pug_daikichi@yahoo.co.jp
authors.forename: Hiroki
authors.initials: H
authors.lastname: Ito
authors.forename: Takashi
authors.initials: T
authors.lastname: Kawahara
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Terao
authors.forename: Takehiko
authors.initials: T
authors.lastname: Ogawa
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yao
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Kubota
authors.forename: Junichi
authors.initials: J
authors.lastname: Matsuzaki
mesh_terms: D005260:Female; D006695:Holmium; D006801:Humans; D017602:Lithotripsy, Laser; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D018666:Ureteroscopy; D014545:Urinary Calculi / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery / Q000628:therapy*
chemical_list: D006695:Holmium