Endosonographic criteria for an internal opening of fistula-in-ano

Abstract

These combined criteria would be of particular help in performing preoperative location of an internal opening with endosonography.

Contrast‐Enhanced endosonography for the diagnosis of anal and anovaginal fistulas

“…The presence of an internal opening was defined on the basis of the following 3 accepted criteria: hypoechoic area in the intersphincteric plane, a defect of the IAS, and a subepithelial breach connected with the intersphincteric tract through the IAS. 2,4,5 Using a soft Silastic catheter (10F Nelaton; Galmed, Bydgoszcz, Poland) introduced into the fistulaÕs tract through the external orifice, about 1 ml of 3% hydrogen peroxide solution was injected slowly into the fistulaÕs tract. After about 15 seconds, scanning of the anal canal was repeated, and the initial non-contrast study was compared with the contrast-enhanced study with regard to the type of fistula, presence of ramifications, and location of the internal opening.…”

“…4 Currently, the location of an internal opening has to be inferred from the following findings: the presence of a hypoechoic defect in the normally hyperechoic intersphincteric plane, a focal defect of the IAS, and a hypoechoic subepithelial breach connected with the intersphincteric tract through the IAS. 2,4,5 Using these criteria in our study, we identified 6 internal openings on non-contrast AES. However, after hydrogen peroxide injection and at surgery, only 3 of them appeared to be correctly identified [3 (27%) of 11].…”

Three-dimensional endoanal ultrasonographic assessment of an anal fistula with and without H2O2enhancement

“…Fistula tracks were visualized as tube-like, hypoechoic lesions. The internal fistula opening was identified as a hypoechoic area in the intersphincteric plane, as a defect in the internal anal sphincter, or as a subepithelial breach that connected to the fistulous tract through an internal sphincter defect [7] . After the pre-enhanced data set was saved, H2O2-enhanced sonography was performed as previously described, with some modifications [8] .…”

Endosonographic evaluation of perianal fistulas and abscesses: comparison of two instruments and assessment of the role of hydrogen peroxide injection

“…The internal opening was identified on the basis of the 3 accepted criteria: hypoechoic area in the inter-sphincteric plane, a defect of the internal anal sphincter, and a subepithelial breach connected with the inter-sphincteric tract through the internal sphincter. 2,7 The presence of abscesses and their size and location in respect to the levator ani muscle were also reported. After the completion of endosonographic evaluation, a cannula was introduced through the external openings and a solution of 3% H 2 O 2 was injected.…”

“…1,3,[5][6][7] Currently, there is an increased availability of mechanical radial endosonoscopes for the diagnosis of upper gastrointestinal tract and pancreato-biliary diseases, and many practitioners use the same equipment for anorectal indications including the diagnosis of perianal fistulas. 8,9 However, a direct comparison of the two examination techniques has not been reported.…”