title: Contrast-enhanced endosonography for the diagnosis of anal and anovaginal fistulas.
abstract: OBJECTIVE
  We assessed whether contrast-enhanced anal endosonography (AES) with hydrogen peroxide improves the identification of anal fistulas and their internal openings compared with non-contrast AES.
  
  
  METHODS
  The study group comprised 12 patients who had various types of anal fistulas with visible external openings. AES was performed before and about 15 seconds after injection of 1 ml of 3% hydrogen peroxide into the fistula tract through the external opening.
  
  
  RESULTS
  Both contrast and non-contrast AES revealed 7 transsphincteric, 2 intersphincteric, 1 suprasphincteric, and 2 anovaginal fistulas. Simple tracts were found in 8 cases and complex tracts in 4 cases on non-contrast AES. Contrast-enhanced AES revealed 9 simple and 3 complex fistulas. One fistula that appeared complex on the non-contrast study appeared simple after contrast agent administration. Contrast-enhanced AES demonstrated more internal openings than non-contrast AES did. Surgery confirmed 11 of the fistulas; an internal opening could not be located surgically for the other tract.
  
  
  CONCLUSIONS
  Contrast-enhanced AES appears to be superior to non-contrast AES in the preoperative assessment of anal and anovaginal fistulas and in demonstrating and locating their internal openings.
authors.affiliation: Imaging Diagnostics Department, II Medical Faculty, Medical Academy, Kondratowicza 8, 03-285 Warsaw, Poland.
authors.forename: Iwona
authors.initials: I
authors.lastname: Sudoł-Szopińska
authors.forename: Wiesław
authors.initials: W
authors.lastname: Jakubowski
authors.forename: Marek
authors.initials: M
authors.lastname: Szczepkowski
mesh_terms: D000293:Adolescent; D000328:Adult; D001004:Anus Diseases / Q000000981:diagnostic imaging* / Q000601:surgery; D003287:Contrast Media; D019160:Endosonography / Q000379:methods*; D005260:Female; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011856:Radiographic Image Enhancement / Q000379:methods*; D012003:Rectal Fistula / Q000000981:diagnostic imaging* / Q000601:surgery; D012006:Rectovaginal Fistula / Q000000981:diagnostic imaging / Q000601:surgery; D012016:Reference Values; D012680:Sensitivity and Specificity; D014623:Vaginal Diseases / Q000000981:diagnostic imaging* / Q000601:surgery
chemical_list: D003287:Contrast Media; D006861:Hydrogen Peroxide