title: How can the assessment of fistula-inano be improved?
abstract: OBJECTIVE
  Fistula-in-ano anatomy and its relationship with anal sphincters are important factors influencing the results of surgical management. Preoperative definition of fistulous track(s) and the internal opening play a primary role in minimizing iatrogenic damage to the sphincters and recurrence of the fistula.
  
  
  METHODS
  Physical examination and endoanal ultrasound (performed with a 10 MHz endoprobe), either conventionally or with an injection of hydrogen peroxide, were performed in 26 consecutive patients. Results were matched with surgical features to establish their accuracy in preoperative fistula-in-ano assessment.
  
  
  RESULTS
  Accuracy rates of clinical examination endoanal ultrasound, and hydrogen peroxide-enhanced ultrasound were 65.4, 50, and 76.9 percent for primary tracks, 73.1, 65.4, and 88.5 percent for secondary tracks, and 80.8, 80.8, and 92.3 percent for horseshoe extensions, respectively. Compared with physical examination and endoanal ultrasound, accuracy of hydrogen peroxide-enhanced ultrasound was higher for transsphincteric and intersphincteric primary tracks and horseshoe extensions. Both endoanal ultrasound and hydrogen peroxide-enhanced ultrasound displayed a significantly higher accuracy in detecting the internal openings (53.8 and 53.8 percent, respectively) compared with clinical evaluation (23.1 percent; P = 0.027).
  
  
  CONCLUSIONS
  Our data suggest that hydrogen peroxide-enhanced ultrasound can be very reliable and useful in the definition of fistula anatomy, its relationship with anal sphincters, and, hence, surgical strategy. It also improves identification of secondary extensions, particularly horseshoe tracks. This method, besides being safe, economic and reputable, both preoperatively and postoperatively, could be helpful in checking operative results and recurrence.
authors.affiliation: Department of Clinica Chirugica, Catholic University, Rome, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Ratto
authors.forename: E
authors.initials: E
authors.lastname: Gentile
authors.forename: M
authors.initials: M
authors.lastname: Merico
authors.forename: C
authors.initials: C
authors.lastname: Spinazzola
authors.forename: G
authors.initials: G
authors.lastname: Mangini
authors.forename: L
authors.initials: L
authors.lastname: Sofo
authors.forename: G
authors.initials: G
authors.lastname: Doglietto
mesh_terms: D000328:Adult; D001003:Anal Canal / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D006801:Humans; D006861:Hydrogen Peroxide; D008297:Male; D008875:Middle Aged; D010808:Physical Examination; D011300:Preoperative Care; D012003:Rectal Fistula / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D012008:Recurrence; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D014463:Ultrasonography
chemical_list: D006861:Hydrogen Peroxide