Anal fistula 

Introduction 

Digestive health

Find out how to beat common digestive problems like bloating and indigestion

An anal fistula is a small channel that develops between the end of the bowel, known as the anal canal, and the skin near the anus.

The end of the fistula can appear as a hole in the skin around the anus. The anus is the opening where waste leaves the body.

Anal fistulas are usually classed as either:

  • simple or complex – depending on whether there is a single fistula tract or interlinking connections
  • low or high – depending on its position and how close it is to the sphincter muscles (the rings of muscles that open and close the anus)

When should I see my GP?

The common symptoms of an anal fistula include:

  • skin irritation around the anus
  • a throbbing, constant pain that may be worse when you sit down, move around, have a bowel movement or cough
  • a discharge of pus or blood when having a bowel movement (rectal bleeding)

You should see your GP if you have any of these symptoms. You may be referred to a specialist in bowel conditions, known as a colorectal surgeon, for further investigation.

Read more about diagnosing an anal fistula.

What causes an anal fistula?

An anal fistula usually develops after an anal abscess (a collection of pus) bursts, or when an abscess has not been completely treated.

A fistula can also be caused by conditions that affect the intestines, such as inflammatory bowel disease (IBD) or diverticulitis.

An anal fistula affects:

  • as many as 50% of people with Crohn's disease
  • up to 30% of people with HIV (a virus that attacks the body's immune system)
  • approximately 30-50% of people with an anal abscess (this is slightly more common in women than men)

Read more information about the causes of an anal fistula.

Treating an anal fistula

Most anal fistulas require surgery because they rarely heal if they are not treated. Several surgical methods are available, depending on where the fistula is and whether it is classed as simple or complex.

You may be able to go home on the day of surgery. However, you may need to stay in hospital for a few days if the fistula is difficult to treat. 

Read more information about treating an anal fistula and recovering from anal fistula surgery.

There is a risk of complications after anal fistula surgery, including:

For example, after the most common type of surgery for a fistula (known as a fistulotomy), the risk of an anal fistula coming back is around 21%.

The risks vary depending on the type of procedure. You can discuss this with your surgeon.

Page last reviewed: 20/06/2014

Next review due: 20/06/2016

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The 2 comments posted are personal views. Any information they give has not been checked and may not be accurate.

Teififisher said on 09 August 2014

I would be really grateful for any recommendations about things to do to relieve pain caused by an anal fistula that I was informed I had last Thursday. A brief history of my problems:
I've had months of problems with back passage pain /haemorrhoids etc and have been advised by my GP to eat plenty of bran, vegetables etc to keep things soft. This has helped as also has some cream (Anoheal) that he gave me. I had a THD done for the haemorrhoids in February and have since had spells of relatively painfree days and others where things have been very sore and stinging, especially after going to the loo.
Last Thursday, I went into hospital to have a rectal examination under anaesthetic following another painful few days, and have now been told I have a fistula which will be removed by surgery that I'll get an appointment for eventually.
My first trip to the loo following this was this morning (two days afterwards) and it was a painful experience - I suppose due to the effects of the anaesthetic and painkillers making me somewhat constipated. The pain was however nothing compared with the agony I was in an hour or so later - really stabbing pains and stinging burning sensation. Paracetamol+ tramadol has eased this gradually during the morning.
More than anything else, I would like to know what things can be recommended to ease the pain and discomfort when this happens. Thanks for any suggestions you may have.

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Teififisher said on 09 August 2014

I had an examination of my back passage under anaesthetic last Thursday after many months of discomfort / pain / problems with haemarrhoids , etc. I have now been told I have a fistula and will be given an appointment for further surgery to have it removed. My first visit to the loo following this was this morning (two days later) and was a painful experience and also produced some bleeding. 30 minutes after this I was in agony with the pain, and painkillers (paracetamol and tramadol) have gradually kicked in.
I think what I would find especially helpful to know is any things others with a similar problem have done to relieve the pain. I have followed my doctor's advice over the past few weeks and had regular Allbran + prunes / prune juice which has kept stools soft. He has also supplied me with Anoheal which has helped. But I still get times when passing motion is painful and then sheer agony between 30 minutes and an hour after visiting the loo.
Any other suggestions please re providing relief?

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