Anal fistula

An anal fistula is a tunnel that develops between your bottom (anus) and your back passage (rectum). An anal fistula is also referred to as a perianal fistula.

By Wallace Health I Medically reviewed by Adrian Roberts.
Page last reviewed: October 2018 I Next review due: October 2021

What is an anal fistula?

An anal fistula can either be a single tunnel or, occasionally, a network of tunnels. It’s usually caused by an infection near the anus.

An anal fistula is a painful and often unpleasant long-term (chronic) condition. Symptoms include discharge, skin irritation, anal discharge and, in some cases, bowel incontinence.

You’re more likely to develop an anal fistula if you’ve had an anal abscess, including a perianal abscess. About one in every two people with an anal abscess also develops an anal fistula.

An anal fistula requires fistula treatment, usually anal fistula surgery.

How to tell if you have an anal fistula

The main symptoms of an anal fistula are:

  • Red, itchy, irritated skin around your anus
  • Throbbing, constant anal pain and swelling around your anus
  • Pus or anal bleeding when you pass a stool
  • Unpleasant discharge from the area around your anus
  • Problems controlling your bowel movements (bowel incontinence)
  • A small hole in the skin near your anus

Talk to your doctor if you’re concerned about symptoms

You can book an appointment with a Spire private GP today.

Book an appointment

Diagnosis and tests for anal fistula

See your GP if you’re regularly experiencing any of the symptoms of an anal fistula. Your GP will ask about your symptoms and your general health, including any history of bowel conditions. Your GP may examine your anus.

If your GP diagnoses - or suspects - an anal fistula, they’ll refer you to a consultant called a colorectal surgeon. At your first appointment, your consultant may refer you for further investigations, including:

  • A proctoscopy – to check the inside of your rectum using a proctoscope, a special telescope with a light on the end
  • A sigmoidoscopy – a flexible tube with a camera on the end which takes images of your rectum and bowel
  • An ultrasound scan, MRI scan and/or CT scan – to provide a detailed picture of inside your rectum

Causes of anal fistula

An anal fistula is often the result of an anal abscess (perianal abscess). As the abscess drains, it creates a tunnel through the skin tissues between the rectum and the anus.

An anal fistula can also be caused by long-term (chronic) bowel conditions, including Crohn’s disease and diverticulitis. Very occasionally, tuberculosis (TB) and HIV infection can cause an anal fistula.

Common treatments for anal fistula

Anal fistula treatment almost always involves anal fistula surgery to close the tunnel. This allows an anal fistula to heal without affecting your bowel continence.

Your consultant will discuss your options with you but these may include:

  • Fistulotomy – opening the anal fistula so it closes and heals as a flat scar
  • Seton techniques – placing a thin silicone thread in the anal fistula, enabling it to drain and heal, a procedure which can be carried out several times
  • Covering the entrance hole to the anal fistula with tissue from your rectum
  • Using special glue to close the anal fistula – this is the only non-surgical treatment currently available for anal fistulas, although a general anaesthetic is still required

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