What is an anal fistula?
An anal fistula is a small tunnel that connects an abscess, an infected cavity in the anus, to an opening on the skin around the anus.
The anus is the external opening through which feces are expelled from the body. Just inside the anus are a number of small glands that make mucus. Occasionally, these glands get clogged and can become infected, leading to an abscess. About half of these abscesses may develop into a fistula.
What causes an anal fistula?
The leading causes of an anal fistula are clogged anal glands and anal abscesses. Other, much less common, conditions that can cause an anal fistula include:
- Crohn’s disease (an inflammatory disease of the intestine)
- Radiation (treatment for cancer)
- Sexually transmitted diseases
- Diverticulitis (a disease in which small pouches form in the large intestine and become inflamed)
What are the symptoms of an anal fistula?
The signs and symptoms of an anal fistula include:
- Frequent anal abscesses
- Pain and swelling around the anus
- Bloody or foul-smelling drainage (pus) from an opening around the anus. The pain may decrease after the fistula drains.
- Irritation of the skin around the anus from drainage
- Pain with bowel movements
- Fever, chills and a general feeling of fatigue
You should see your doctor if you notice any of these symptoms.