What are the symptoms?

The main symptoms are diarrhoea and abdominal pain. There may be some blood or mucus in the faeces, especially when the lowest part of the gut is affected. The pain is usually caused by digested food or faeces building up in narrowed or inflamed areas often coming on an hour or so after eating. Sometimes, there is a tight blockage in the intestine causing severe, griping abdominal pain after eating, with swelling of the abdomen and vomiting. Losing weight is common when there is a lot of inflammation and many people with the condition feel excessively tired. Some people also have a temperature or sweats at night. There may also be sore, red eyes, swollen painful joints and skin rashes.

How is it diagnosed?

When someone visits their doctor with symptoms of persistent diarrhoea and abdominal pain, he or she will try to decide whether special tests are needed to look for the possibility of Crohn’s disease and ulcerative colitis. There are many causes of diarrhoea in young adults including the irritable bowel syndrome (IBS), and infection (for example after travel abroad). The doctor will listen to the symptoms and ask about any of the related symptoms described above and also whether there is anyone in the family with Crohn’s disease or ulcerative colitis. An examination will then find out if there are any signs of inflammation (such as tenderness in the abdomen or a lump) and whether there are any general signs of illness such as looking pale or underweight. Finally, a blood test might be arranged to see if there are changes in the blood which suggest inflammation. If the doctor suspects that Crohn’s disease is a possibility, a referral will be made to a specialist for further tests.

Which tests are used to diagnose Crohn’s disease?

The most frequent test used to diagnose Crohn’s disease is a colonoscopy. This involves the passage of a tube with a videocamera at the end around the colon and, where possible, into the last part of the small intestine. Laxative preparation is needed before the examination to clear the bowel and allow good views of the lining of the intestine. In most cases, sedation is given through a vein at the start of the procedure to minimise some feelings of discomfort associated with passage of the tube along the colon. By doing this test, doctors can get very accurate pictures of the state of the lining if the intestine and take samples for examination in the laboratory. If the colon nd last part of the small intestine are seen to be normal, Crohn’s disease is very unlikely to be present.

In some cases, other tests are also needed. For example, a barium follow through test allows images to be taken of the whole of the small intestine (by swallowing special liquid barium which shows up on xrays taken at intervals during the test). Scans such as ultrasound or CT scanning may also be needed, especially if anabscess or problems on the outside of the intestine are suspected.