Symptoms of an anal fistula 

There are several common symptoms of an anal fistula.

Symptoms include:

  • skin irritation around the anus (the opening where waste leaves the body)
  • 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 you have a bowel movement – read more information about rectal bleeding

If your fistula was caused by an abscess that you still have, you may have:

  • a high temperature of 38ºC (100.4ºF) or over
  • fatigue
  • a general feeling of being unwell

If your fistula was caused by inflammation of the intestines (part of your digestive system) – for example, because of a condition such as Crohn's disease – you may also have:

Read more information about the causes of an anal fistula.

Types of fistula

An anal fistula is usually classified as:

  • 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 sphincter muscles are two rings of muscles that open and close the anus. They are known as the internal and external sphincter muscles.

The most common types of anal fistula are:

  • intersphincteric fistula – the fistula tract (channel) crosses the internal sphincter and opens on the surface of the skin next to the anus
  • transsphincteric fistula – the fistula tract passes through both the internal and external sphincters and opens on the surface of the skin next to the anus

Other types of anal fistula can:

  • begin at a different part of the colon (large intestine)
  • extend in a different direction so the fistula does not open next to the anus
  • develop in a horseshoe shape, with two open ends either side of the anus

Page last reviewed: 20/06/2014

Next review due: 20/06/2016