A blindfolded endoscope traveling past a few patches of inflamed intestine walls.

Can Crohn’s Disease and Ulcerative Colitis Be Missed on a Colonoscopy?

The 2 most common forms of inflammatory bowel disease (IBD) are Crohn’s disease and ulcerative colitis (UC). Your doctor may perform a few different tests to determine which disorder you may have.

UC and Crohn's are usually easily distinguished from each other. However, there are times when the diagnosis may be more complicated. Sometimes, UC and Crohn's may look alike.

They may also look like other diseases such as chronic colitis or diverticulitis. In these cases, it may take longer to be correctly diagnosed.1

How are Crohn's and colitis diagnosed?

Gastroenterologists have many different techniques to determine if you have a type of IBD or another disorder. A very common procedure is endoscopy. This is when the doctor will use a very small but long camera to look at your digestive tract.

This allows the doctor to see if there is any damage to your digestive organs and even take small samples of tissue to later examine under a microscope.2

What is the PillCam?

The GI tract is very long and intricate. Because of this, it can be difficult to use an endoscope to see the tract from start to finish. Engineers created a technique called wireless video capsule endoscopy (also known as the PillCam).

It consists of a very small camera the size of a pill that you can swallow. It can capture images of the entire GI tract for the doctor to examine later. This allows your doctor to see areas of your digestive tract that classic endoscopy or imaging cannot show.2

Doctors may also use CT imaging and blood tests. All of these techniques are used together with your symptoms to make a final diagnosis.2

Can Crohn's or UC be missed on a colonoscopy and other tests?

It is very important to have the right diagnosis so you can be treated correctly. However, IBD diagnosis can be complex.

Any tissue samples taken during endoscopy will be sent to a pathologist. The pathologist will examine the tissue with and without a microscope, looking for signs of IBD.1

The tissue changes seen in UC and Crohn's can be seen in other diseases. IBD may look like other types of less common chronic colitis, like collagenous colitis and lymphocytic colitis. It may also be confused for diverticulitis or diversion colitis. Bacterial or parasitic infections may also mimic IBD patterns.1

It is possible to have multiple GI disorders at once. It can be more difficult to diagnose your symptoms if you have a secondary infection like cytomegalovirus or a C. difficile infection. Your doctor may have to run more tests in this case.1

The inflammation caused by UC is limited to the large intestine (colon). Different types of Crohn’s disease affects different areas of the digestive tract, including the parts of the small intestine, stomach, and colon.

In some cases, the inflammation is patchy, meaning it only affects certain areas of the colon. This can happen in children or in those living with mild IBD. It may be difficult to see or biopsy these patches of colon, so it may take longer to diagnose IBD because it can be missed on colonoscopy.1

What is indeterminate colitis?

In about 10 percent of IBD cases, it is not clear if the diagnosis is UC or Crohn's disease. This can occur if you are not currently experiencing a flare-up.

It can also occur in the very early stages of IBD or in chronic IBD. You may be diagnosed with indeterminate colitis (IC) at that time. Your doctor may then order blood tests, antibody panels, and more imaging such as an MRI to determine a more specific diagnosis.3

If you have more questions about your diagnosis, speak to your primary care doctor or gastroenterologist.

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This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The InflammatoryBowelDisease.net team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.

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