What's in this article?
What is Anus?
The anus is the opening where the gastrointestinal tract ends and exits the body. The anus starts at the bottom of the rectum, the last portion of the colon (large intestine). The anorectal line separates the anus from the rectum.
Tough tissue called fascia surrounds the anus and attaches it to nearby structures.
Circular muscles called the external sphincter ani form the wall of the anus and hold it closed. Glands release fluid into the anus to keep its surface moist.
A plate-like band of muscles, called the levator ani muscles, surround the anus and form the floor of the pelvis. A network of veins lines the skin of the anus.
Anus Disorders
- Anal cancer
- Anal fissure
- Anal itching
- Anorectal abscess
- Anorectal fistula
- Foreign objects in the anus and rectum
- Hemorrhoids
- Levator syndrome
- Pilonidal disease
- Proctitis
- Colorectal cancer
- Rectal prolapse
Anus Tests
- Physical examination: A doctor may inspect the outside of the anus, and insert a gloved finger to feel for abnormal areas on the inside of the anus.
- Sigmoidoscopy: An endoscope (flexible tube with a lighted camera on its tip) is inserted into the anus and moved into the colon. Sigmoidoscopy can only reach part of the colon for viewing.
- Colonoscopy: An endoscope is inserted into the anus, and the entire colon is viewed to look for problems.
- Fistulography (fistulogram): A liquid that helps improve image contrast is injected into an abnormal opening in or near the anus, and X-ray films are taken. Fistulography can detect an abnormal connection (fistula) between the anus and skin.
Anus Diagnosis
- A doctor’s evaluation
- Anoscopy or sigmoidoscopy
- Possibly barium enema
Next, a doctor looks into the anus and rectum with a 3- to 10-inch (about 7- to 25-centimeter) rigid viewing tube (anoscope or proctoscope). A longer, flexible tube (sigmoidoscope) may then be inserted so that the doctor can observe as much as 2 or more feet of the large intestine. An anoscopy or sigmoidoscopy is generally uncomfortable but not painful. However, if the area in or around the anus is painful because of an abnormal condition, the doctor may give a local, regional, or even general anesthetic before proceeding with the examination. Sometimes a cleansing enema to rid the lower part of the large intestine of stool is given before sigmoidoscopy. Tissue and stool samples for microscopic examination and cultures may be obtained during sigmoidoscopy. A barium enema x-ray may also be done.
