What IBS tests will I need?

One of the first things people ask is "what tests will I need for IBS?" Whilst this is a great question it's important to know that there isn't a specific test for IBS. Testing for IBS is a process of elimination, which helps to rule out other possible causes of gut symptoms.

Basic IBS tests

If your doctor suspects that you may be suffering from IBS they may request that you undergo some routine blood tests. These may include tests such as:

• Full blood count (FBC)
• Erythrocyte sedimentation rate (ESR) or plasma viscosity
• C-reactive protein (CRP)
• Antibody testing for coeliac disease (endomysial antibodies [EMA] or tissue transglutaminase [TTG])

These tests will likely all be performed on the same day. Usually, you won't be asked to fast before these routine tests but always double-check to be sure.

It's very important not to cut gluten from your diet before you have the antibody testing for coeliac disease. However, If you've been eating a gluten-free diet, then this test may need to be delayed for a few months. In order to take the antibody test you'll need to reintroduce gluten back into your diet under the supervision of your doctor. 

Additional IBS tests

If you're experiencing any red flag symptoms your doctor may feel that further investigations are needed. It's really important that you attend these appointments to get a clearer picture of your gut health. Above all, ruling out the cause of red flag symptoms should be done before making any self-led changes to your diet. The types of additional tests that you may be asked to do include:

• Ultrasound
• Rigid/flexible sigmoidoscopy
• Colonoscopy; barium enema
• Thyroid function test
• Faecal ova and parasite test
• Faecal occult blood
• Hydrogen breath test (for lactose intolerance and small intestinal bacterial overgrowth, SIBO).

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These additional tests are usually not required in the majority of patients with IBS in the absence of red flag symptoms.

You can hear all about my colonoscopy experience and results here.

https://youtu.be/QJnnuZ3-LmA

What do the tests show?

Typically the basic tests for IBS will look for;

• inflammation that might suggest ulcerative colitis, Crohn's or cancer
• infection that might suggest food poisoning or infectious disease
• anaemia or blood abnormalities that might suggest blood loss or cancer
• specific antibodies that might suggest coeliacs disease
• blood in stool that might suggest haemorrhoids, fissures, fistulas, polyps, ulcers, Crohn's or cancer

Generally, the additional tests for IBS will look for;

• signs of parasites
• physical abnormalities of the structure of the digestive system
• visual signs of inflammation, fissures, masses or tumours
• biopsies to microscopically test for infection, inflammation and irregularities
• tolerance to lactose
• hydrogen output that might suggest small intestinal bacterial overgrowth (SIBO)

Once you have the test results back your doctor will confirm the possible cause of your symptoms. If a diagnosis of IBS is given this generally means that your symptoms fit within the Rome IV criteria for diagnosing IBS.  It may also mean that tests for other underlying conditions were negative or inconclusive at this time.

Do you suspect you may have IBS? Could you do with some support as you navigate your tests, doctors appointments and diagnosis? We break it all down into easy to manage steps in these posts.

Have you had all the relevant tests to put your mind at ease? Share your journey in the comments below.