Specialised Tests for Diarrhoea Predominant IBS

Before having specialised tests for diarrhoea predominant IBS, it is important that the standard blood, stool and endoscopy tests have been done. If these are normal, you may require one or more other tests.

These include:

  • SehCAT study for bile salt malabsorption
  • Lactulose hydrogen breath test for small bowel bacterial overgrowth
  • Smart Pill physiology study for various problems including caecal malfermentation
  • Lactose hydrogen breath test for lactose intolerance

SehCAT study for Bile Salt Malabsorption

If you have on-going chronic diarrhoea, a possible cause is the inability of your body to re-absorb bile acids, a substance produced by your liver to break down the fats in the food you eat.

Normally these bile acids are released into the top of the small bowel. They are then re-absorbed back into the body at the bottom of the small bowel.

If your body can’t re-absorb these bile acids properly, they escape from the small bowel into the large bowel. This causes diarrhoea similar to that caused by IBS.

When you go for the test you will be asked to swallow a tablet, which contains a special labelled form of bile acid. One week later, you will have a scan to see how much of the label remains in the body

If the test shows that you aren’t absorbing bile acids properly, then you can be treated with drugs to help soak up the excess bile. This should stop the diarrhoea.

Lactulose hydrogen breath test for Small Intestinal Bacterial Overgrowth (SIBO)

A condition called small-bowel bacterial overgrowth (SIBO), where there is an excess of bacteria in your intestines, can mimic a lot of the symptoms of IBS, including diarrhoea, constipation and abdominal discomfort.

SIBO occurs in many people who have had abdominal surgery or cancer treatment such as radiotherapy. It can also occur without any obvious cause.

In order to rule out this easy to treat condition, your doctor may send you for a lactulose hydrogen breath test. Lactulose is a special type of sugar. It tastes sweet, but it is not absorbed through the wall of the gut into the body. It is therefore safe for anyone to use, including people with diabetes.

During the test you will be given a tablet containing the lactulose and asked to give a sample of breath every 15 minutes for 2-3 hours. If the levels of hydrogen in your breath are higher than average it is an indication that you may be suffering from small-bowel bacterial overgrowth, and you will most likely be given antibiotics to treat the condition.

The preparation for this test is very important. Before the test, you will be asked to leave out certain foods for a couple of days. This makes sure that the test result is accurate. Please always check with the doctor or nurse about which foods you should leave out before the test.

Small bowel physiology – the ‘Smart Pill’ test

Many problems with digestive health can originate in the small bowel, including malabsorption, Crohn’s disease, motility problems and IBS itself. In order to gain a better insight into how your small bowel is working, your doctor may ask you to undergo a Smart Pill test.

This is a very new test. It involves swallowing a small, disposable capsule that travels through your digestive system, sending information back to a measuring device that you carry around with you. It works wirelessly.

The test can take a total of 3-5 days, during which you go about your normal business; once the pill has passed right through your digestive system, your doctor will take a look at the recordings it has made and use them to aid their diagnosis.

The pill can relay all kinds of information about your small bowel, including intestinal motility, pH, temperature and pressure. The combination of results the pill gives will determine the most accurate diagnosis.

This test is not widely available. But if one of the London Gastroenterology Centre doctors thinks it is useful for you, we are pleased to tell you that we can organise this test very easily.

Tests for Lactose Intolerance

Lactose intolerance is an important and common cause of diarrhoea, bloating and abdominal pain. It is also easily treated.

Please remember that everyone has slightly different symptoms. You need an expert to sort out which problems you might have. Our doctors at the London Gastroenterology Centre do these specialist tests frequently so know when to do them and how to interpret them. Please feel free to make a private consultation. Phone us on 020 7183 7965.

We are available to see patients daily for private consultations

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