When a tubular organ or blood vessel becomes excessively narrow such that it can no longer perform as nature intended, it is a condition referred to by physicians as stenosis. Anal stenosis, also known as an anal stricture, is the narrowing of the anal canal, located just before the anal sphincter. The anal sphincter is a complex part of the body that maintains a seal that can be opened to discharge body waste. It is strong enough to restrict the passage of any fecal material but sensitive enough to differentiate between solid, liquid, and gas. There are actually two anal sphincter muscles … internal and external. The internal anal sphincter is a thin, white muscle wrapped around the anal canal. The internal sphincter contracts during rest and sleep, and keeps small amounts of liquid and gas from escaping unexpectedly.

The external anal sphincter or sphincter ani externus is a flat plane of skeletal muscle fibers, elliptical in shape and intimately adherent to the skin surrounding the margin of the anus. In a considerable proportion of cases the fibers decussate in front of the anus, and are continuous with the superficial transverse perineal muscle. Posteriorly, they are not attached to the coccyx, but are continuous with those of the opposite side behind the anal canal.

Your doctor will ask questions about your condition and perform a physical exam that usually includes a visual inspection of your anus. A probe may be used to examine this area for nerve damage. Normally, this touching causes your anal sphincter to contract and your anus to pucker.