The dimension of the anal fissure is elliptical and follows the course of the anal canal. In 90% of the cases the ulcer is located at the midline posteriorly in the anal canal, only in 10% they are located anteriorly.
In case of multiple fissures or fissures that are located lateral it could be a hint for a specific disease (e.g. tuberculosis, Crohn’s disease, syphilis).
A flat ulcer where the edges are hard to determine characterizes the acute anal fissure. At the base of the fissure are fibers of the muscularis mucosa visible.
In the chronic anal fissure is typical a tag of skin at the edge of the anus (sentinel pile), proximal a hypertrophic anal papilla and at the fissure base are fibers of the internal anal sphincter muscle visible.
There might be also a abscess or fistula present.
