Abstract
PURPOSE: The purpose of this study is to present a new standard classification of fistulas to clarify the low intersphincteric fistula and posterior complex fistula.
PERINEOPELVIC SPACES: The perineopelvic spaces are classified as follows: subcutaneous and submucous spaces (IL and IH, the boundary is the dentate line), low and high intersphincteric spaces (IIL and IIH, the boundary is the dentate line), perianal space (IIL), ischiorectal fossa (III) and the supralevator space (IV). Because we identified a septum of connective tissue, including vessels and nerves in the ischiorectal fossa (we named the septum as the septum of ischiorectal fossa). The fossa is separated into two spaces: lower and higher (IIIL and IIIH). Furthermore, we identified two important spaces in the mid posterior anal region: the posterior deep space (IIIP) and the space of Courtney (IIICourtney). The anterior border of the posterior deep space is the internal sphincter, the superior border is the inferior surface of the puborectalis, while the inferior and lateral borders are the anterior surfaces of the external sphincter. The anterior border of the space of Courtney is the posterior surface of the deep external sphincter, while the superior and inferior borders are the superficial external sphincter.
CLASSIFICATION: Anal fistulas are classified based on the extension form of the fistula tract. The types of fistulas are as follows: subcutaneous fistula, submucous fistula, low and high intersphincteric fistulas, posterior deep fistula, low and high ischiorectal fistulas, and supralevator fistula.
