Crohn's disease

Crohn's disease is an inflammatory condition that affects the gastrointestinal tract. It a long-term medical condition, and as yet there is no cure.

Most cases of Crohn's disease are diagnosed between the ages of about 15 and 30. It is not common in children before puberty.


Initial symptoms of Crohn’s disease commonly include:

  • intermittent episodes of cramping abdominal pain, particularly in the bottom right-hand corner of the abdomen; and
  • diarrhoea.

Sometimes these symptoms are severe and mistaken for appendicitis or an obstruction of the intestine.

Other symptoms include:

  • fever;
  • weight loss;
  • loss of appetite;
  • tiredness;
  • blood in your stool;
  • mouth ulcers; and
  • nausea and vomiting.

Although most of the time people with the disease may feel well, when the disease flares up, any of these symptoms may appear. Some people may find infections (such as the flu), stress, some types of medications or certain foods bring on a disease flare-up.


Some of the complications of Crohn’s disease include:

  • fistulas – abnormal openings connecting the bowel to the skin surface (usually near the anus) or another organ (such as the bladder);
  • anal fissures – a small tear in the tissue around the anus that can cause pain, bleeding and itching;
  • abscesses – a collection of pus, often occurring near the anus (perianal abscess);
  • ulcers around the anus and adjoining area; and
  • obstruction of the bowel.

Sometimes, malabsorption occurs, leading to vitamin or mineral deficiencies.

Crohn's disease can also affect other parts of the body and lead to:

  • pain and swelling in the joints similar to arthritis;
  • skin rashes;
  • inflamed eyes; and inflammation of the liver or bile ducts – leading to jaundice (a yellowing of the skin).

What is the difference between Crohn's disease and ulcerative colitis?

Crohn's disease and ulcerative colitis are the 2 main types of inflammatory bowel disease. There are several differences between these 2 conditions.

Crohn's disease affects the full thickness of the bowel and can occur in any part of the gastrointestinal tract from the mouth to the anus. With Crohn's disease there may be patches of healthy bowel next to patches of diseased bowel.

The inflammation of ulcerative colitis, on the other hand, affects the innermost lining (the mucosa) of only the large bowel (the colon and rectum). There is continuous inflammation, as opposed to the patchy inflammation of Crohn's disease.

People with Crohn's disease may show different symptoms depending on which part of the bowel is involved.

What causes Crohn's disease?

The cause of Crohn's disease remains unknown, although intensive research is continuing. Doctors have proposed several theories to explain it, including:

  • the body’s immune system (which normally provides a defence against foreign matter) not recognising its own tissues and attacking itself;
  • infection by bacteria or viruses;
  • environmental factors; and
  • genetic factors — having a close relative with Crohn’s disease increases your risk of developing the disease.

Smoking can increase the risk of developing Crohn's disease, and people with Crohn's disease who also smoke are less likely to respond to treatment and more likely to have relapses.

Tests and diagnosis

Your doctor may suspect you have Crohn’s disease based on your symptoms and physical signs. Because symptoms can be similar to those of other conditions such as irritable bowel syndrome or a gastrointestinal infection, you may need a series of tests to confirm the diagnosis.


  • Blood tests may be done to test for anaemia, inflammation and mineral deficiencies.
  • Testing of stool samples may also be recommended by your doctor to help make the diagnosis.
  • To confirm the diagnosis you will need a direct examination of your bowel by flexible sigmoidoscopy or colonoscopy. Both these procedures are usually performed on a day surgery basis in a hospital, and involve a flexible tube with a light on it being inserted into your anus so the doctor can see the inside of your bowel. You will be put under light sedation to make the procedure more comfortable. The doctor may also take a tiny sample of tissue from your bowel for examination under a microscope. You may also need an upper endoscopy, where a tube is passed through the mouth to look at the upper end of your gut.
  • A small bowel X-ray may be recommended if the Crohn's disease is suspected in the upper part of the intestine. For this test you will be asked to drink a chalky liquid containing barium before X-rays are taken of your gastrointestinal tract. The liquid highlights your stomach and small bowel and helps show up any abnormalities.
  • Occasionally, a wireless capsule endoscopy may be performed. This test involves swallowing a capsule that has a tiny camera inside it. The camera takes photos of your small bowel, which are transmitted to a data recorder that you wear around your waist. The capsule is single-use only, and will exit the body painlessly in your stool after a couple of days. It can be flushed down the toilet.
  • A CT or MRI scan may also be recommended to provide images of the gastrointestinal tract and tissues outside the bowel.


1. Gastroenterological Society of Australia (GESA); Digestive Health Foundation (DHF). Information about inflammatory bowel disease (IBD); Third Edition, 2013. (accessed Oct 2015).
2. MayoClinic. Crohn’s disease (updated 13 Aug 2014). (accessed Oct 2015).
3. Gastroenterological Society of Australia (GESA); Digestive Health Foundation (DHF). Information about capsule endoscopy; Second Edition 2012. (accessed Oct 2015).