Diagnosis of IBS
Everyone has a bout of abdominal pain and diarrhea or constipation now and then. That’s not unusual. It is unusual when the symptoms persist or keep coming back. When that happens, it’s time to see a doctor to find out why.
Making the Diagnosis
There are no tests that identify IBS (like standard blood tests, x-rays, scopes, or scans). Instead, IBS is diagnosed based on defined patterns of signs and symptoms.
A doctor will start by asking about symptoms and health history, and then do a physical exam and limited tests. Your doctor may suggest a blood test to check for Celiac disease if you are experiencing diarrhea or diarrhea and constipation (a positive test should be confirmed by a biopsy). Unless there are "warning" signs this is generally all that is needed to diagnose IBS.
Warning Signs and Symptoms
Warning signs and symptoms are not typical of IBS. The doctor may want to run extra tests if you have any of the following:
- anemia and other abnormal blood tests,
- blood in the stool,
- unexplained weight loss,
- fever, or
- a family history of inflammatory bowel disease or other diseases of the colon
IBS Signs and Symptoms
The typical signs and symptoms of IBS are...
- pain or discomfort in the belly (abdomen),
- that happens several days or more per month over at least the last 3 months, and
- is related to changes in the way your bowel moves, meaning the pain/discomfort…
- gets better after a bowel movement, and/or
- happens when bowel movements become more often or less often, and/or
- when stools are getting harder or softer
Other Common Digestive Symptoms
The signs and symptoms listed above are distinguishing features of IBS. But other symptoms are also often felt by persons with IBS - digestive symptoms such as...
- Bloating
- Heartburn
- Early feeling of fullness
- Nausea
- Upper belly discomfort or pain that comes and goes (dyspepsia)
- Feelings of urgency (the need to find a restroom fast)
- Passage of mucus in the stool
- Feeling of "incomplete" bowel emptying
Some Symptoms Aren't Digestive
And symptoms that don't seem related to the digestive tract such as...
- Fatigue
- Muscle pain
- Sleep disturbances
- Sexual dysfunction
- Low back pain
- Headache
Biological Markers?
There currently is no consistent biological marker of IBS that can be used to make the diagnosis. Research interest is underway to find a biological marker, or set of markers. They include use of a blood test, stool sample, or tissue sample from the colon. These would enhance the diagnostic accuracy of symptom criteria.
Tests
If you have the typical symptoms of IBS, and your doctor says, "Your tests are negative" it means that you don't have some other disease. Tests look for other things, not for IBS.
At this point your doctor might also say something like, "Based on your symptoms and exam, you have IBS." Your signs and symptoms fit the standard for diagnosing IBS. The next step is to learn all you can about IBS and work with your doctor on a treatment plan that fits you.
IBS is a problem with the way a system works. There is no visible evidence that shows up on a test. That's not the same thing as "nothing is wrong." People have painful headaches, but nothing shows up on tests. It's the same with IBS.
What if you have a test result that is positive? It may be a minor problem. You may have something else along with your IBS, or you may have something else entirely. A doctor will help you sort this out.
The Bottom Line
A doctor familiar with IBS will likely be able to make a diagnosis based on your symptoms, a history and physical exam, and few basic tests to rule out something else. Once you have a diagnosis you can start finding ways to best manage and treat your IBS.
Discover more about IBS:
The Rome III Diagnostic Criteria*
The Rome criteria are a system for making diagnosis based on symptoms. For IBS this includes recurrent abdominal pain or discomfort** at least 3 days per month in the last 3 months associated with 2 or more of the following:
- Improvement with defecation
- Onset associated with a change in frequency of stool
- Onset associated with a change in form (appearance) of stool
* Criterion fulfilled for the last 3 months with symptom onset at least 6 months prior to diagnosis.
** "Discomfort" means an uncomfortable sensation not described as pain.