Fig. 8

H₂O₂-enhanced 3D TRUS images of transsphincteric fistula with bilateral intersphincteric extension with two internal openings. a Red arrow demonstrates the secondary internal opening as a breach in the continuity of the epithelial layer of the rectum at the posterolateral wall b and c. The course of track shown as a hyperechoic shadow d. The red arrow demonstrates the primary internal opening inside the anal canal as a breach in the continuity of the epithelial layer at mid anal canal level