Anorectal fistulas are common among people who have an anorectal abscess, Crohn disease, or tuberculosis.
Anorectal fistulas can cause pain and produce pus.
The diagnosis is based on an examination and other viewing techniques.
Treatment nearly always involves surgery, but some less invasive alternatives now exist.
The rectum is the section of the digestive tract above the anus where stool is held before it passes out of the body through the anus. The anus is the opening at the end of the digestive tract where stool leaves the body. (See also Overview of the Anus and Rectum Overview of the Anus and Rectum The anus is the opening at the end of the digestive tract where stool leaves the body. The rectum is the section of the digestive tract above the anus where stool is held before it passes out... read more .)
The Digestive System
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Most fistulas begin in a deep gland in the wall of the anus or rectum. Sometimes fistulas occur after drainage of an anorectal abscess Anorectal Abscess An anorectal abscess is a pus-filled cavity caused by bacteria invading a mucus-secreting gland in the anus and rectum. Bacteria infect a blocked gland in the anus or rectum and create an abscess... read more , but often the cause cannot be identified. Fistulas are more common among people with Crohn disease Crohn Disease Crohn disease is an inflammatory bowel disease where chronic inflammation typically involves the lower part of the small intestine, the large intestine, or both and may affect any part of the... read more 
or tuberculosis Tuberculosis (TB) Tuberculosis is a chronic contagious infection caused by the airborne bacteria Mycobacterium tuberculosis. It usually affects the lungs. Tuberculosis is spread mainly when people breathe... read more 
. They also occur in people with diverticulitis Diverticulitis Diverticulitis is inflammation of one or more balloon-like sacs (diverticula). Infection may or may not develop. Diverticulitis usually affects the large intestine (colon). Left lower abdominal... read more 
, cancer, or an anal or rectal injury. A fistula in an infant is usually a birth defect and is more common among boys than girls.
Fistulas that connect the rectum and vagina (called rectovaginal fistulas) may result from radiation therapy, cancer, Crohn disease, or an injury to a mother during childbirth.
Symptoms of Anorectal Fistula
An infected fistula may be painful and may discharge bloody pus.
Diagnosis of Anorectal Fistula
A doctor's evaluation
Sometimes anoscopy, sigmoidoscopy, or colonoscopy
A doctor can usually see one or more openings of a fistula or can feel the fistula beneath the surface.
A probe may be inserted to determine its depth and direction. By looking through an anoscope (a short, rigid tube) inserted into the rectum and exploring with the probe, the doctor may locate the internal opening of the fistula. Inspection with a sigmoidoscope (see Endoscopy Endoscopy Endoscopy is an examination of internal structures using a flexible viewing tube (endoscope). Endoscopy can also be used to treat many disorders because doctors are able to pass instruments... read more ), which is a much longer viewing scope, also helps the doctor locate the internal opening of the fistula and helps the doctor determine whether the problem is being caused by cancer, Crohn disease, or another disorder. Colonoscopy is done if the doctor suspects Crohn disease (see diagnosis of Crohn disease Diagnosis Crohn disease is an inflammatory bowel disease where chronic inflammation typically involves the lower part of the small intestine, the large intestine, or both and may affect any part of the... read more ).
Treatment of Anorectal Fistula
Surgical procedures
For fistulas caused by Crohn disease, drugs
Previously, the only effective treatment was surgery to open the fistula (fistulotomy). During surgery, sometimes the sphincter is partially cut. If too much of the sphincter is cut, the person may have difficulty controlling bowel movements. Newer surgical procedures use advancement flaps (flaps are stretched over the opening of the fistula) or other procedures to close the fistula tract. Biologic plugs and fibrin glue instillations are alternatives to fistulotomy.
If the person has diarrhea or Crohn disease, which may delay wound healing, surgery usually is not done. Drugs used to treat Crohn disease Treatment Crohn disease is an inflammatory bowel disease where chronic inflammation typically involves the lower part of the small intestine, the large intestine, or both and may affect any part of the... read more can help a fistula close.
