title: Accuracy of hydrogen peroxide enhanced endoanal ultrasonography in assessment of the internal opening of an anal fistula complex.
abstract: BACKGROUND
  The aim of this study was to evaluate the accuracy of hydrogen peroxide-enhanced ultrasound in localizing the internal opening of the anal fistula.
  
  
  METHODS
  A retrospective review of all patients with anal fistula who underwent hydrogen peroxide-enhanced ultrasound was performed. The results of hydrogen peroxideenhanced ultrasound and intraoperative findings on the basis of operative reports were correlated.
  
  
  RESULTS
  A total of 57 patients (47 men) of mean age of 45.7 (range, 21-77) years underwent hydrogen peroxide-enhanced ultrasound with a diagnosis of anal fistula; 36 patients underwent surgery. The intraoperative internal opening correlated with the hydrogen peroxide-enhanced ultrasound report in 22 of 36 patients (61.1%). In 5 patients, the hydrogen peroxide-enhanced ultrasound yielded false-positive information with a positive predictive value of 84%. Four of the 7 patients with falsenegative hydrogen peroxide-enhanced ultrasound findings had supra- and extrasphincteric fistulas.
  
  
  CONCLUSIONS
  There is a 61.1% correlation between hydrogen peroxide-enhanced ultrasound and surgical findings of the internal opening with a positive predictive value of 84%. If no internal opening was seen on hydrogen peroxide-enhanced ultrasound, it strongly suggests the possibility of a supralevator or extrasphincteric fistula.
authors: Department of Colorectal Surgery, Cleveland Clinic Florida, 2950 Cleveland Clinic Blvd, Weston, FL 33331, USA.
authors: I
authors: I
authors: Moscowitz
authors: M K
authors: MK
authors: Baig
authors: J J
authors: JJ
authors: Nogueras
authors: E
authors: E
authors: Ovalioglu
authors: E G
authors: EG
authors: Weiss
authors: J J
authors: JJ
authors: Singh
authors: S D
authors: SD
authors: Wexner
mesh_terms: D000328:Adult; D000368:Aged; D003287:Contrast Media; D005260:Female; D006801:Humans; D006861:Hydrogen Peroxide; D008297:Male; D008875:Middle Aged; D012003:Rectal Fistula / Q000000981:diagnostic imaging* / Q000601:surgery; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014463:Ultrasonography
chemical_list: D003287:Contrast Media; D006861:Hydrogen Peroxide