title: Predicting calyceal access for percutaneous nephrolithotomy with computed tomography multiplanar reconstruction.
abstract: OBJECTIVE
  Objective parameters in computed tomography (CT) scans that could predict calyceal access during percutaneous nephrolithotomy have not been evaluated. These parameters could improve access planning for percutaneous nephrolithotomy. We aimed to determine which parameters extracted from a preoperative multiplanar reconstructed CT could predict renal calyceal access during a percutaneous nephrolithotomy.
  
  
  METHODS
  From January 2009 through April 2011, 230 patients underwent 284 percutaneous nephrolithotomies at our institution. Sixteen patients presented with complete staghorn calculi, and 11 patients (13 renal units) were analyzed. Five parameters were extracted from a preoperative reconstructed CT and compared with the surgical results of percutaneous nephrolithotomy.
  
  
  RESULTS
  Fifty-eight calyces were studied, with an average of 4.4 calyces per procedure. A rigid nephroscope was used to access a particular calyx, and a univariate analysis showed that the entrance calyx had a smaller length (2.7 vs. 3.98 cm, p=0.018). The particular calyx to be accessed should have a smaller length (2.22 vs. 3.19 cm, p=0.012), larger angles (117.6 vs. 67.96, p<0.001) and larger infundibula (0.86 vs. 0.61 cm, p=0.002). In the multivariate analysis, the only independent predictive factor for accessing a particular calyx was the angle between the entrance calyx and the calyx to be reached (OR 1.15, 95% confidence interval [CI], 1.053-1.256, p=0.002).
  
  
  CONCLUSIONS
  The angle between calyces obtained by multiplanar CT reconstruction is the only predictor of calyx access.
authors.affiliation: Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Division of Urology, São Paulo/SP, Brazil.
authors.forename: Giuliano B
authors.initials: GB
authors.lastname: Guglielmetti
authors.forename: Alexandre
authors.initials: A
authors.lastname: Danilovic
authors.forename: Fabio C M
authors.initials: FC
authors.lastname: Torricelli
authors.forename: Rafael F
authors.initials: RF
authors.lastname: Coelho
authors.forename: Eduardo
authors.initials: E
authors.lastname: Mazzucchi
authors.forename: Miguel
authors.initials: M
authors.lastname: Srougi
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D007670:Kidney Calices / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009403:Nephrostomy, Percutaneous / Q000379:methods*; D009929:Organ Size; D011237:Predictive Value of Tests; D012016:Reference Values; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014545:Urinary Calculi / Q000000981:diagnostic imaging* / Q000601:surgery; D055815:Young Adult