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Anal fistulas are small tunnels that can develop from the anal canal to the skin around the bottom. This article takes a look at some of the causes of anal (perianal) fistulas.
Beverley shares her story of living with complex anal fistulas.
Anal fistulas (also known as perianal fistulas) can be caused by a number of different things.
The causes of an anal fistula include:
One of the most common causes of an anal fistula is having an anal abscess. An anal abscess happens when an anal gland, a small gland around the anus (where poo comes from) that produces fluid, becomes blocked and infected which causes pus to build up, becoming an abscess.
When an anal abscess bursts a tunnel can form from the anal gland where the abscess was exiting at the skin.
Up to 50% of people with an anal abscess will develop a fistula1.
Certain conditions can cause your intestines to become inflamed and anal fistulas can be a complication of this.
Conditions which cause this type of inflammation include:
They are common in people who have Crohn’s disease, with up to 50% of people with Crohn’s disease developing some form of fistula at some point in the 20 years after diagnosis3.
Sometimes developing a fistula will be the first sign that someone has inflammatory bowel disease (IBD).
The exact reasons why they are so common in people with Crohn’s disease isn’t known, but the fact that the inflammation in Crohn’s disease affects every layer of the intestine is thought to play a part. In ulcerative colitis it is only the top layer of the intestine that is affected.
Other causes include:
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