A perianal fistula is an inflammatory condition that affects the region around the anal canal with a presence of a fistulous tract across
the anal sphincters. Perianal fistula has a high tendency to recur because of undetected infection at surgery, causing significant morbidity and
often requiring repeated surgical treatments. Failure to recognize occult lesions result in recurrent fistula and convert a simple fistula into a complex fistulizing process .Once the
fistulizing process becomes complex , the chance of healing is greatly reduced. Knowledge of the anatomy of the anal sphincter complex and
surrounding spaces is crucial for image interpretation. The anal canal extends from the levatorani muscle cranially to the anal verge caudally
and is surrounded by the internal and external anal sphincters. The internal sphincter is the inferior extension of the inner circular
smooth muscle of the rectum and is primarily responsible for resting involuntary anal continence. The external sphincter is composed of
striated skeletal muscle, which is contiguous with both the levatorani and puborectalis muscles superiorly and is primarily responsible for
voluntary continence.
Last date updated on December, 2024