Diagnosing IBS

What causes IBS?

Doctors don’t know why some people get IBS and others don’t.

What is known is that people with IBS have an extra-sensitive nerve response in the gut and abnormalities in the rhythm of the muscular contractions. Because of the hypersensitivity of the nerves, the muscular contractions are easily upset - too fast and it may cause diarrhoea, too slow and it may cause constipation.

Many factors may contribute to the development of IBS including:

  • Infection – in up to 25% of cases, symptoms of IBS start soon after an attack of gastroenteritis, commonly seen as diarrhoea. During the infection, toxins that are released may damage nerve fibres in the gut, leading to disordered contraction of the bowel muscle.
  • Food intolerance – some people may be sensitive to certain foods. Impaired absorption of sugars, such as lactose and fructose, is the most common dietary trigger for IBS.
  • General diet – some cases of IBS occur because the diet is poor. Low fibre diets, for example, can cause constipation. Some people find spicy or sugary foods cause problems.
  • Emotional stress – stress seems to play a significant role in IBS. As the contractions in the bowel are controlled by nerves, anything that affects these nerves can disturb bowel function. This is why many people get diarrhoea when they are nervous.
  • Genetic factors – it is not unusual for IBS to occur within a family.
  • Medications – certain drugs (such as antibiotics, antacids and painkillers) can lead to constipation or diarrhoea.

How is IBS diagnosed?

A diagnosis of IBS is based on the symptoms as there is no specific test for IBS.

Your doctor will ask you about your symptoms, take a medical history and may perform a physical examination as well as some tests just to rule out the possibility of other problems.

Some of the diagnostic tests your doctor may request include:

  • Blood tests
  • Stool tests
  • Examination of the stomach (endoscopy)
  • Investigation of the bowel (colonoscopy or sigmoidoscopy)

If you suspect you have Irritable Bowel Syndrome, it is important to seek medical advice to make sure your symptoms are not caused by any other illness, such as diverticulitis, inflammatory bowel disease or polyps. Gluten intolerance (a protein found in wheat and other grains) and lactose intolerance to dairy products may produce many of the same symptoms
as IBS.

This quiz can help you decide if you should see a doctor about your symptoms.
Question 1 of 6
Do you have recurrent abdominal pain?
YES
NO
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