title: Assessment and classification of never operated and recurrent cryptoglandular fistulas-in-ano using hydrogen peroxide enhanced transanal ultrasound.
abstract: OBJECTIVE
  Classification and visualization of fistula-in ano is used to determine surgical treatment according to the type of fistula, predict the recurrence rate and incontinence risk and compare the results of treatment published in literature. Hydrogen peroxide enhanced transanal ultrasound (HPUS) with the peroxide introduced through the external opening of the fistula gives a clear and accurate visualization of the track in relation to the sphincters. The aim of this study was to review never operated and recurrent cryptoglandular fistulas-in-ano visualized with the aid of HPUS in order to establish the anatomical differences.
  
  
  METHODS
  Eighty-one patients with never operated (48) or recurrent (33) cryptoglandular fistulas-in-ano were assessed by clinical examination and HPUS.
  
  
  RESULTS
  Never operated fistulas were single track, trans- or inter-sphincteric fistulas in 80%. In 15%, the tracks were sinus with no connection to the pectinate line. Two patients (5%) had a transsphincteric fistula with a ramification. No supra- or extra-sphincteric fistulas were found in the never operated fistula group. In the recurrent fistula patients, 57% had a single trans or intersphincteric track, 15% of the patients had a single track supra or extrasphincteric fistula and 27% had a ramified fistula.
  
  
  CONCLUSIONS
  All never operated cryptoglandulair fistulas-in-ano were inter- or trans-sphincteric. An extra track was found in 5%. Recurrent fistulas-in-ano were supra or extrasphincteric in 15% and ramified in 27%. Therefore, never operated fistula-in-ano does not require any special investigation before surgical treatment. However, before treating recurrent fistulas, visualization by HPUS is recommended to detect supra or extrasphincteric fistulas or ramification.
authors.affiliation: Department of Gastroenterology, Vrije Universiteit Medical Centre, Amsterdam, the Netherlands.
authors.forename: C E
authors.initials: CE
authors.lastname: Sloots
authors.forename: R J
authors.initials: RJ
authors.lastname: Felt-Bersma
authors.forename: A C
authors.initials: AC
authors.lastname: Poen
authors.forename: M A
authors.initials: MA
authors.lastname: Cuesta