Crohn's disease

What is Crohn's disease?

Crohn's disease is an inflammatory condition that affects the gastrointestinal tract. It is called a chronic condition because it lasts a long time and is a long-term medical condition. As yet there is no cure.

What happens in Crohn's disease?

Crohn's disease causes changes in the bowel wall, which can range from mild redness to a severe state in which all the layers of the bowel wall become inflamed and so become thickened, deeply ulcerated and deformed. Fistulas (abnormal openings connecting the bowel to the skin surface near the anus) can develop, and obstruction of the bowel can occur.

How does it progress?

Although most of the time people with the disease may feel well, the disease can flare up from time to time and result in an attack of symptoms that can be extremely debilitating, including chronic diarrhoea, abdominal pain and bloating.

Who is affected?

Most cases of Crohn's disease are diagnosed between the ages of about 15 and 35. It is not common in children before puberty.

What is the difference between Crohn's disease and inflammatory bowel disease?

Crohn's disease is one of a group of conditions known as inflammatory bowel disorders, which are more common in Western societies than in other parts of the world. Crohn's disease and ulcerative colitis are the best-known of these diseases and because they share similarities, the two conditions are often grouped together and called inflammatory bowel disease (IBD).

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 the diseased bowel.

The inflammation of ulcerative colitis, on the other hand, affects the innermost lining (the mucosa) of the large bowel (the colon and rectum) and is a continuous inflammation, as opposed to the patchy inflammation of Crohn's disease. About 15 per cent of people affected with ulcerative colitis will have pan-colitis where the whole colon is affected, and 85 per cent will have less extensive involvement of the colon, where only the rectum or the rectum and some of the adjacent colon is affected.

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

What are the symptoms of Crohn's disease?

Intermittent episodes of abdominal pain, particularly in the bottom right-hand corner of the abdomen, and diarrhoea are often the earliest signs. Sometimes these symptoms are severe and mistaken for appendicitis or an obstruction of the intestine.

There may also be sores, ulcers, cracks or skin tags (which can look like haemorrhoids) around the anus and adjoining area, as well as blood in the stool.

Other symptoms include:

  • fever;
  • weight loss;
  • loss of appetite;
  • tiredness;
  • a feeling of fullness in the abdomen;
  • pain on passing bowel motions if the anus is affected;
  • itching around the anus (if the anus is affected);
  • vomiting; and
  • rarely, skin rashes, inflamed eyes or jaundice (a yellowing of the skin).

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

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 changes in diet bring on an attack.

The inflammation in Crohn's disease can also affect other parts of the body and lead to pain and swelling in the joints similar to arthritis, or in the spine or lower back. Rarely, the inflammation can affect the liver, bile ducts, or eyes.

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 chemicals; and
  • genetic factors — the disease does tend to run in families although there doesn’t seem to be a clear cut pattern to explain why.

Although many people who have the disease find their symptoms are worse when they are under emotional stress, doctors don’t believe stress plays a part in causing the disease — it just acts as a trigger to set off attacks.

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 early relapses.

How is it diagnosed?

Your doctor may suspect you have the disease by your description of the 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 or stool tests may be done to test for anaemia and infection. You may also need a direct examination of your bowel by 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 the gut.

Other outpatient procedures that may help in the diagnosis of Crohn's disease are a barium enema or small bowel X-rays. A small bowel X-ray will 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 internal organs and helps show up any abnormalities.

A barium enema will highlight abnormalities in the lower part of the intestinal tract. A white chalky liquid containing barium will be run into your bowel via the anus and X-ray pictures taken.

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.

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