There isn't a specific test for IBS, as it doesn't cause any obvious detectable abnormality in your digestive system.
However, if you have the symptoms of IBS, your GP will usually recommend that you have a blood test to rule out other conditions that cause similar symptoms, such as an infection or coeliac disease (a stomach condition caused by gluten intolerance).
Your doctor will generally diagnose IBS by seeing if your symptoms match those that are typical of the condition.
Your doctor will suspect that you have IBS if one of the following 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.
Having at least two of the following symptoms should confirm that you have IBS:
- a change in how you pass stools, such as needing to strain, feeling a sense of urgency or feeling that you haven't 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 that you may have a more serious condition than IBS. These symptoms include:
- unexplained weight loss
- a swelling or lump in your abdomen or back passage
- bleeding from your back passage
- anaemia
Further testing may also be recommended if you have a family history of bowel or ovarian cancer, or if you are over 60 years old and you've had a change in your bowel habits that has lasted for more than six weeks.
The types of test that you may have are:
- a sigmoidoscopy – where a device called a a thin, flexible tube that is attached to a small camera and light (sigmoidoscope) is used to examine your back passage and the lower section of your bowel
- a colonoscopy – where a device similar to a sigmoidoscope, called a colonoscope, is used to examine your entire bowel
