title: Endosonographic evaluation of perianal fistulas and abscesses: comparison of two instruments and assessment of the role of hydrogen peroxide injection.
abstract: OBJECTIVE
  The aims of this study were to compare the performance of a mechanical radial endosonoscope and an endorectal electronic probe and to evaluate the value of hydrogen peroxide (H(2)O(2)) injection in the diagnosis of perianal fistulas.
  
  
  METHODS
  Sixty-one patients underwent clinical and endosonographic studies for suspected perianal fistulas or abscesses. Endosonography was performed using two instruments: a mechanical radial endosonoscope (Olympus GF-UM20) and an electronic endorectal probe (Hitachi EUP-R53). The patients were re-examined during and following H(2)O(2) injection using both systems.
  
  
  RESULTS
  Thirty-seven fistulous tracts were visualized with the electronic endorectal probe versus only 9 with the mechanical radial endosonoscope. Four patients had anal stenosis, precluding the use of the larger electronic probe. Three fistulas were detected in these patients using the mechanical radial endosonoscope. H(2)O(2) injection was not feasible in 26 patients (43%). Visualization of 11 (31%) fistulas improved after administration of H(2)O(2). Six fistulous tracts not detected before H(2)O(2) administration were clearly visualized during injection and for several minutes thereafter.
  
  
  CONCLUSIONS
  Work-up of perianal fistula should be preferably performed using the endorectal electronic probe. However, the mechanical radial endoscope is preferred in patients with anal stricture. H(2)O(2) injection should become an integral part of every sonographic study of perianal fistulas.
authors.affiliation: Department of Gastroenterology and Hepatology and Department of Surgery, Sheba Medical Center, Tel-Hashomer, Israel.
authors.forename: Yaakov
authors.initials: Y
authors.lastname: Maor
authors.forename: Yehuda
authors.initials: Y
authors.lastname: Chowers
authors.forename: Moshe
authors.initials: M
authors.lastname: Koller
authors.forename: Oded
authors.initials: O
authors.lastname: Zmora
authors.forename: Simon
authors.initials: S
authors.lastname: Bar-Meir
authors.forename: Benjamin
authors.initials: B
authors.lastname: Avidan
mesh_terms: D000038:Abscess / Q000000981:diagnostic imaging*; D000293:Adolescent; D000328:Adult; D000368:Aged; D001004:Anus Diseases / Q000000981:diagnostic imaging*; D019160:Endosonography / Q000295:instrumentation*; D005260:Female; D006801:Humans; D006861:Hydrogen Peroxide / Q000008:administration & dosage; D015552:Injections, Intralesional; D008297:Male; D008875:Middle Aged; D012003:Rectal Fistula / Q000000981:diagnostic imaging*
chemical_list: D006861:Hydrogen Peroxide