Figure 3.

Procedure of the modified transanal opening of the intersphincteric space. A: An arc-shaped incision was made at the posterior median intersphincter groove of the perianal area, and the sphincter space was opened; B: The probe was inserted into the sphincter space to identify the internal opening; C: The probe was passed through the internal opening; D: A small part of the internal sphincter and connective tissues inferior to the internal opening were incised, and the edges of the incision were ligated and trimmed; E: A circular incision was made at the external incision, and then tunnel-like fistulectomy of the fistulas at the lateral side of the external sphincter was performed; F: Intact skin on and beneath the external sphincter was preserved.