title: Accuracy of hydrogen peroxide-enhanced ultrasound in the identification of internal openings of anal fistulas.
abstract: OBJECTIVE: This prospective study was designed to assess the accuracy of hydrogen peroxide-enhanced ultrasound in the identification of internal openings of anal fistulas, with surgical findings as the golden standard. PATIENTS AND METHODS: A total of 143 consecutive patients (102 men; mean age, 45 years) with fistula-in-ano were assessed by hydrogen peroxide-enhanced ultrasound before surgery involving one radiologist. Ultrasound was performed using a B & K Diagnostic Ultrasound System trade mark with a 10-MHz rotating endoprobe. Hydrogen peroxide (3%) was infused into the fistula. All operations were perfomed by the same surgeon who was unaware of results of anal endosonography. RESULTS: In 128 (89.5%) patients, an internal opening was identified at surgery. Correct identification of an internal opening endosonographically was recorded in 80 (62.5%) patients. The internal opening was correctly identified by ultrasound in 32% (8/25) of patients with intersphincteric fistulas, in 77% (70/91) with transsphincteric fistulas, and in 17% (2/12) with suprasphincteric fistulas. CONCLUSION: The accuracy of hydrogen peroxide-enhanced anal endosonography for the identification of internal openings was still insufficient to justify pre-operative endosonography as a diagnostic method for routine use in patients with fistula-in-ano.
authors.affiliation: Unit of Coloproctology, Departments of Surgery and Radiology, Hospital Virgen del Camino, Universidad Pública de Navarra, Pamplona, Spain.
authors.forename: H
authors.initials: H
authors.lastname: Ortiz
authors.forename: J
authors.initials: J
authors.lastname: Marzo
authors.forename: G
authors.initials: G
authors.lastname: Jiménez
authors.forename: M
authors.initials: M
authors.lastname: DeMiguel