Diagnosing IBS

There are no specific tests for IBS, as it does not cause any obvious detectable abnormalities in your digestive system.

If you have the symptoms of IBS, your GP will not always need to order blood tests to help diagnose you.

However, in a few cases they may recommend blood tests to rule out other conditions that cause similar symptoms, such as an infection or coeliac disease (a stomach condition caused by gluten intolerance).

IBS is usually diagnosed by carrying out a physical examination and checking whether your symptoms match those typical of the condition.

Your GP will suspect you have IBS if one of the following criteria applies to you.

  • you have abdominal pain or bloating that is relieved when you pass a stool
  • you have abdominal pain or bloating associated with episodes of diarrhoea or constipation
  • you are passing stools more frequently than normal

If you have at least two of the following symptoms, a diagnosis of IBS will be confirmed:

  • a change in how you pass stools, such as needing to strain, feeling a sense of urgency or feeling you have not emptied your bowels properly
  • bloating, hardness or tension in your abdomen
  • your symptoms get worse after eating
  • you pass mucus from your back passage

Further tests

Further tests are usually only needed when you have certain “red flag” symptoms that indicate you may have another serious condition. These symptoms include:

  • unexplained weight loss
  • a swelling or lump in your abdomen or back passage
  • bleeding from your back passage
  • anaemia (a lack of red blood cells)

Further testing may also be recommended if you have a family history of bowel cancer or ovarian cancer, or if you are over 60 years of age and you have had a change in your bowel habits that has lasted for more than six weeks.

Tests you may have include:

  • sigmoidoscopy  where a sigmoidoscope (a thin, flexible tube with a small camera and light at one end) is used to examine your back passage and the lower section of your bowel
  • colonoscopy  where a device similar to a sigmoidoscope, called a colonoscope, is used to examine your entire bowel

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