Complications of Crohn’s disease

The two most common complications associated with Crohn’s disease are:

  • bowel obstruction – severe inflammation that causes sections of your bowel to narrow and harden, causing your bowel contents to become stuck in your bowel
  • fistula – a fistula is a channel that develops between the end of the bowel (anal canal) and the skin near the anus

These are discussed in more detail below.

Bowel obstruction

If your bowel becomes obstructed, you will either not be able to pass any stools, or you will only be able to pass watery stools.

Other symptoms of bowel obstruction include:

  • abdominal pain and cramping
  • being sick (vomiting)
  • bloating
  • an uncomfortable feeling of fullness in your abdomen

A bowel obstruction requires immediate medical treatment. Left untreated, there is a risk that the bowel could split (rupture). This can lead to internal bleeding and widespread infection.

If you suspect that your bowel is obstructed, contact your GP as soon as possible. If this is not possible, telephone NHS Direct on 0845 46 47.

If a bowel obstruction is suspected, it is likely that you will be admitted to hospital so that your health can be carefully monitored. In some cases, it may be possible to clear the obstruction by switching you to a liquid-only diet and using medication to reduce inflammation. However, if this does not work, surgery will be required to unblock the bowel.

Temporary colostomy or ileostomy

You may require a temporary colostomy while your bowel heals. A colostomy is an operation to divert a section of your colon and attach it to an opening in your abdominal wall. The opening is known as a stoma. A pouch is attached to the stoma to collect your stools. Once your bowel has healed, the colon can be reattached and the stoma sealed.

An ileostomy is where a section of your small bowel is diverted and attached to an opening in your abdominal wall.

If you have repeated episodes of bowel obstruction, a permanent colostomy may be recommended.


If your digestive system becomes scarred due to excessive inflammation, ulcers can develop.

Over time the ulcers develop into tunnels, or passageways, that run from one part of your digestive system to another or, in some cases, to the bladder, anus or skin. These passageways are known as fistulas.

Small fistulas do not usually cause symptoms. However, larger fistulas can become infected and cause symptoms such as:

  • a constant, throbbing pain
  • a high temperature (fever) of 38°C (100°F) or above
  • blood or pus in your faeces (stools)

If a fistula develops on your skin (usually on, or near, the anus) it may release a foul-smelling discharge.

Surgery is usually required to treat a fistula. During the operation, the surgeon will cut open the fistula while you are under general anaesthetic. They will flush out the contents of the fistula and it should then heal into a flat scar.

Read more about treating a fistula.

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