title: Transperineal ultrasonography in perianal Crohn's disease and recurrent cryptogenic fistula-in-ano.
abstract: OBJECTIVE
  Successful anal fistula care is aided by specialized imaging accurately defining the site of the internal opening and fistula type. Imaging techniques are complementary, designed to answer specific anatomical questions. There are limited data concerning the clinical value of transperineal ultrasound (TP-US) in both cryptogenic fistula-in-ano and perianal Crohn's disease (PACD). The aim of the study was to assess the accuracy of TP-US compared with operative findings in patients with perirectal sepsis.
  
  
  METHODS
  Patients with recurrent cryptogenic anal fistula and PACD referred for sonography were examined using TP-US by a single examiner blinded to the operative results. Fistulae were categorized by the Parks classification predicting the site of the internal fistula opening. Ancillary horseshoe collections, abscesses and secondary tracks were defined.
  
  
  RESULTS
  Fourteen patients with PACD and 27 patients with recurrent cryptogenic fistula-in-ano were analysed with comparative images and operative data. Correlation of fistula type for cryptogenic and PACD patients respectively was 23/27 (85.2%) and 12/14 (85.7%), with a correlative internal opening site (when found at surgery) of 16/22 (72.3%) and 12/14 (85.7%). Misclassification of fistula type in cryptogenic cases occurred in the presence of ancillary abscesses with associated acoustic shadowing. In PACD patients, TP-US was used when anal stenosis precluded endoanal ultrasonography, assisting in the diagnosis of recto-vaginal fistulae.
  
  
  CONCLUSIONS
  TP-US is a useful complementary technique to assess fistula-in-ano and has special advantage when there is anal canal distortion, complex fistula type or suspicion of a recto-vaginal fistula.
authors.affiliation: Department of Surgery and Transplantation, Tel Hashomer Hospital, Ramat Aviv, Israel.
authors.forename: A
authors.initials: A
authors.lastname: Nevler
authors.forename: M
authors.initials: M
authors.lastname: Beer-Gabel
authors.forename: A
authors.initials: A
authors.lastname: Lebedyev
authors.forename: A
authors.initials: A
authors.lastname: Soffer
authors.forename: M
authors.initials: M
authors.lastname: Gutman
authors.forename: D
authors.initials: D
authors.lastname: Carter
authors.forename: A P
authors.initials: AP
authors.lastname: Zbar
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001003:Anal Canal / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D003424:Crohn Disease / Q000000981:diagnostic imaging* / Q000601:surgery; D019160:Endosonography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012003:Rectal Fistula / Q000000981:diagnostic imaging* / Q000601:surgery; D012006:Rectovaginal Fistula / Q000000981:diagnostic imaging*; D012008:Recurrence; D012189:Retrospective Studies
keywords: Transperineal ultrasound; fistula-in-ano; perianal Crohn's disease