IBS Tests

Is It Possible To Test Irritable Bowel Syndrome?

It took me two years, from the time I started to feel unwell, to finally get an IBS diagnosis and it was mainly an elimination process.

It is not easy for a health practitioner to definitively diagnose Irritable Bowel Syndrome, because in appearance the bowel seems normal, even though it does not function normally.

Usually the diagnosis comes after the doctor is familiar with your full medical history and other conditions have been investigated and ruled out, as a lot of the IBS symptoms are common to other, often more serious, ailments.

Some of the most common IBS symptoms are:

  • Stomach bloating
  • Excessive gas (flatulence)
  • Stomach pain and cramps (often relieved by bowel movement)
  • Feeling of incomplete stool evacuation after going to the toilet
  • Straining during bowel movement
  • Feeling of urgency to evacuate stools
  • Three or more bowel movements/day (diarrhea)
  • Three or less bowel movements/week
  • Liquid or almost liquid stools
  • Hard/dry stools
  • Presence of mucus in the stools
  • Altered frequency of stool and/or altered consistency of stool

Considering the difficulties of diagnosing IBS, researchers have attempting to classify IBS symptoms by using two main criteria: the Manning Criteria and the subsequent Rome Criteria.

A lot of researchers affirm that IBS should not be a “diagnosis of exclusion” which is applied after other testing have been done, but that instead, IBS should be positively diagnosed and further testing avoided, when patients meet the Manning or Rome criteria and have no red flag symptoms.

Manning criteria

The Manning criteria, developed in 1978 to help the diagnosis of IBS, consists in a list of questions, which are asked to the patient to see if they meet at least 3 of the following criteria:

  1. Frequent bowel movements with pain associated
  2. Looser stools with pain associated
  3. Abdominal pain relieved by defecation
  4. Noticeable abdominal bloating
  5. Feeling of incomplete stools evacuation
  6. Passage of mucus

Rome criteria

A few years later, in 1988, a group of physicians in Rome defined more accurate criteria to diagnose IBS. These guidelines are known as the “Rome Criteria” and the most recent guidelines for IBS are in the Rome III category C1.

According to this criteria the symptoms of recurrent abdominal pain or discomfort and a marked change in bowel habit need to occur for at least six months, with symptoms experienced on at least three days of at least three months and two or more of the following must apply:

  • Pain is relieved by a bowel movement
  • Onset of pain is associated with a change in frequency of stool
  • Onset of pain is associated with a change in the appearance of stool 

“Red flag” signs

Patient is over the age of 50 or has:

  • Unexplained weight loss

  • Blood in stools

  • Anaemia

  • Fever

IBS Tests

In addition to the Manning and Roma Criteria, there are several tests that your doctor may recommend to rule out other illnesses, such as hydrogen breath tests, stool tests, blood tests, x-rays and CT scans. Depending on the symptoms, the doctor could also refer you to a gastroenterologist (a specialist for the digestive system). 

Hydrogen Breath Tests:

A fairly simple and painless test, the  “Hydrogen Breath Test” may measure not only the presence of hydrogen, but also the presence of methane,  because approximately 35% of people do not produce hydrogen, but actually produce methane or even a combination of the two gases. It is to be noted that some patients, who are called “Non-Responders”, don’t produce either gases and at the moment it has not been determined whether those patients may actually produce another gas. 

Hydrogen breath tests are used in the diagnosis of several conditions , by drinking a beverage containing the substance (lactose, fructose etc.) and usually every 15 minute, the patient will need to blow in a bag, where the hydrogen (and often methane) presence is tested. The test may be slightly different from country to country.

The main conditions tested with the breath hydrogen test are:

Lactose Malabsorption

Lactose is the sugar found in milk. Those who are intolerant to lactose don’t produce the enzyme lactase and therefore are unable to digest lactose, causing them cramps, bloating, diarrhea etc.

Fructose Malabsorption

Formerly named “dietary fructose intolerance” (DFI), fructose malabsorption, is a digestive disorder in which people have difficulties absorbing fructose, which is a sugar found in several food, such as onions, wheat, pears, cherries (fructose and other FODMAPs food list). The symptoms after consuming food which is high in fructose are: cramps, bloating, diarrhea etc.

Fructose malabsorption is not to be confused with hereditary fructose intolerance, a potentially fatal condition in which the liver enzymes that break up fructose are deficient.

Small Bowel Bacterial Overgrowth Syndrome (SBBOS) or Small Intestinal Bacterial Overgrowth (SIBO)

Another condition that can be diagnosed with the Hydrogen Breath Test  is the over-growth of bacteria in the small intestine. This condition can also cause cramps, bloating, diarrhea etc.

Imaging Tests:

Flexible Sigmoidoscopy or Colonoscopy

It’s a test that uses a flexible, lighted tube camera to investigate the lower part of the colon (sigmoidoscopy) or the whole colon (colonoscopy), to rule out other bowel conditions.

X-Ray (radiography)

Doctors may suggest to have an X-rays to obtain an image of the colon.

CT – Computerized Tomography scan

When suffering from abdominal pains, a CT scans of the abdomen and pelvis may help identify or rule out other causes. 

Lower GI series

This test is also done by x-RAY, to identify any problem with the large intestine. The doctor will fill the large intestine with a liquid (barium) toeasily , if there is something unusual. 

Blood tests

Blood tests can help rule out coeliac disease. 

In women a blood test looking for a protein called CA125 could identify ovarian cancer.

A full blood count can rule out anaemia, which is linked to various gut disorders.

Other tests like the Erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) – which can show if there is inflammation in the body (which does not occur with IBS).

Stool tests

A stool test is often done to look for bacteria or parasite and/or also to look for a protein called faecal calprotectin. This may be present if you have Crohn’s disease or ulcerative colitis, but is not present in IBS.





Please note that I’m not a doctor, a nutritionist, a registered dietician or other health practictioner. In this blog I am sharing my experience with IBS, food and life. This is purely my experience and research. When it comes to your health and fitness, consult your GP and do your research.

About Larah

I have been suffering from Irritable Bowel Syndrome for many years, but it took a longtime to get a diagnosis, since then I have been following a low FODMAP diet, which has changed my life for the better. This is my story and experience with IBS and the low FODMAP diet.

4 comments on “IBS Tests

  1. Again another great resource and article for IBS clients of mine to read that I will be sure to share with them.

  2. For my dad, he was actually happy when he was diagnosed with IBS. He had been suffering silently for so long that he was relieved to finally know what was causing him all of his problems. This is a great post to put out there because I think if people were more aware of the symptoms & what they could mean.. they would take steps to see a doctor sooner rather than later.
    Here is a link that you can check out as well: http://www.webmd.com/ibs/ibs-when-you-should-see-doctor

  3. Great advice. I too have been diagnosed with IBS and it took a while for that diagnoses to be made official. I also recommend seeing your GP and raise your concerns and ask for tests.

    • Thank you Robbie5 for your comment. I wish you all the best with the management of your IBS symptoms. Take care

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