How is IBD Diagnosed?

Jan 21, 2017 by

You can have me read this article to you instead of reading it yourself…

Or you can read it the old-fashioned way below…

It doesn’t do much good to talk about what IBD is and what symptoms it can cause if we don’t have a way of confirming whether or not someone has it, right?

Well, that’s not exactly true, but it is helpful to understand how this condition can be diagnosed, because a diagnosis is your clearest path to understanding what is happening and how to deal with it.

There are a number of tests and studies that are conducted for people that are thought to have some form of IBD.  In fact, for those that have already been diagnosed, you may even have some of these studies conducted multiple times.  So it is very important to understand what they entail and when/why they are being completed.

I promise that the “Chelsey Take” below is quite different than what you have found elsewhere.  Hopefully this whole series has been worth your reading thus far!

Blood Tests

There are some markers in the blood that can help your doctor to see if the cause of the symptoms you are experiencing is related to inflammation.  This can be used at the stage of diagnosis, and also during phases of remission and relapse to provide information about what is going on in your body.  These tests look for markers of inflammation, such as counts of your blood cells and something called C-reactive protein (CRP).

There are also some newer tests available that can help to distinguish between ulcerative colitis and Crohn’s disease.  These tests look for specific antibodies, which are products produced by the immune system that direct its attack on the tissues in the intestine.  These antibodies occur differently with these two classes of IBD, so this test can be helpful in clarifying which one is actually the cause of your symptoms.  However, they are not a diagnosis – they typically need to be used in addition to the more invasive tests we will discuss in a minute in order to confirm what is going on.

Stool Tests

Your doctor will want to collect samples of your stool to evaluate what is going on in your intestine.  These samples will typically be very watery because you are experiencing diarrhea, and that is fine.

The most common test is simply to look for the presence of blood.  It is often quite obvious that your stools are bloody, but sometimes, if the blood is from higher up in the intestine, it will not look the same or be as clear to the naked eye that there is blood in the stool.

There are also other factors that can be evaluated in stool tests.  These include calprotectin, a protein that has a correlation with the inflammation in IBD.  It is also an opportunity to test for specific infectious agents that might be causing the symptoms.  It is always very important for a doctor to rule out a severe infection before diagnosing someone with IBD, and this provides an opportunity to look for this possible cause.


Endoscopy involves the use of a small tube that has a camera attached to it in an effort to visualize the GI tract.  It can be conducted in a number of ways, which we will break down below.


This is both an exploratory and diagnostic test that allows the doctor to obtain a better understanding for the state of your lower GI tract.  This is often the first place that a doctor will start to determine if your symptoms are caused by inflammation and where that inflammation is occurring.  It is helpful for both Crohn’s disease and ulcerative colitis, as the doctor will be looking for factors that differentiate the two classes.

With this test, the doctor will place a camera up through your rectum and into your colon, allowing him to examine your colon and lower small intestine.  He is also able to look for any concerns in addition to characteristic inflammation, such as ulcers and blockages.  Another important function of this test is that it allows the doctor to take biopsies of your intestine.  Biopsies of affected tissue allow for better understanding of what kind of inflammation is occurring and to what extent.

Prior to having this procedure completed, you will be asked to ‘clean out’ your lower GI tract for the doctors.  This is typically accomplished by drinking a large quantity of a laxative that goes by a variety of names.  The main ingredient is called polyethylene glycol, but it can come in different packages, which include names like GoLytely and MoviPrep (really clever, right?).  These basically cause you to evacuate the contents of your intestine through pretty significant diarrhea.

For the average person, colonoscopies are done to check for signs of colon cancer at specific ages.  The preparation is considered an unpleasant nuisance.  However, when a colonoscopy is done for someone experiencing the symptoms of IBD, the preparation can be much more uncomfortable.  If you are experiencing diarrhea consistently, the doctor may ask you to prepare for the test in a different way, including through the use of an enema.

This procedure requires a small amount of sedation.  Luckily that sedation also causes amnesia, so you don’t have to remember the experience once it is over.  But that also means you might repeat yourself a few times as you come out of the haze!

One more final point before I get off this unpleasant topic.  Colonoscopies may need to be conducted at different points in time so that the doctor can evaluate the state of your disease (is it better, worse, the same, etc).  So while it might initially be used to diagnose you, it may continue to be used to assess your condition.


A sigmoidoscopy may also be called a flexible sigmoidoscopy or a flex sig.  This is similar to a colonoscopy in that it is conducted using a camera that enters through the rectum.  However, it only looks at the rectum and the sigmoid colon, which is the portion of the colon closest to the rectum (the lower colon).  As you can imagine, this test would typically only be conducted for people that have inflammation limited to this one area.

With a sigmoidoscopy, enemas are more commonly used as preparation because only a smaller part of your intestines must be cleared out to conduct the test.  However, there may be times when the doctor will ask you to do a full ‘clean out’.  Feel free to ask him to explain why if you find yourself silently wondering!  He may recognize that in this case it is overkill, and enemas alone would be adequate.  It does happen!

Again, the state of the colon can be evaluated and biopsies can be taken.  The major difference with this test is that you typically are NOT sedated.  So it might result in some additional discomfort that you were apt to forget about with a colonoscopy.  For instance, you will remember the insertion of the tube.  You may also experience some discomfort when the intestine is inflated with air for better viewing.  It is not a painful experience, but it is one that is forgotten thanks to the sedation used with colonoscopies.

Upper Endoscopy

This is both an exploratory and diagnostic test that allows the doctor to obtain a better understanding for the state of your upper GI tract.  This will typically only be done for those with Crohn’s disease to evaluate the extent of the disease and where it is occurring throughout the GI tract.

With this test, the doctor will place a camera down your throat to examine your esophagus, stomach, and the upper part of the small intestine.  He is also able to take biopsies of the tissue and to look for any concerns in addition to characteristic inflammation, such as ulcers, hernias, and blockages.

No preparation is required for this test other than some fasting beforehand.  This procedure does utilize sedation, much like with a colonoscopy, so you will not have to remember the experience once it is over.

Barium Testing

Barium is a very interesting product because even though it is used for imaging, it is not actually radioactive.  Instead, it is a substance that x-rays cannot pass through, which makes it stand out loud and clear on scans.  In this case, it coats the walls of the GI tract, allowing the doctor to visualize the flow and shape of your GI tract.

When used for IBD, this test is typically chosen for exactly the reason just stated – to visualize the flow and shape of the GI tract.  This will allow the doctors to see if there are any very constricted areas of the intestine where the passageway has become very small (string sign) or any other structural concerns.

If your small intestine is being evaluated, then you will be asked to swallow a lot of barium, which is a kind of chalky, milky substance.  When you pass the barium in your stool, it will appear pale and white, which can be concerning if you are not prepared for it.

If your large intestine is being evaluated, then the barium may be administered as an enema.  As you can imagine, you will have to prepare for this test by clearing out your large intestine.  This may be accomplished through the use of enemas, as well as through a more robust ‘clean out’ regimen as we already discussed.

CT Scan (Computerized Tomography)

This is a scan in which multiple x-rays are taken at one time from a variety of angles to produce a ‘clear’ picture of the area of interest.  In this case, the pictures would be taken of your GI tract, and the whole area is of interest, because this test might allow the doctor to identify causes of symptoms other than IBD.  Within the intestine, this test may identify abscesses, fistulas, and intestinal blockages.

The preparation for this test usually involves fasting beforehand.  You will be asked to drink radiologic contrast (the stuff that lights up on scans) when you arrive, which often does not taste particularly delicious.  It can also cause diarrhea – something to be aware of if you are currently already experiencing a lot of diarrhea as a symptom.

Other Tests

Leukocyte Scintigraphy

This is a newer, less commonly used test that basically tracks where your white blood cells are going.  Because white blood cells pour into sites of inflammation, this is helpful for identifying sites of inflammation within the GI tract.

The test requires a blood draw, in which your white blood cells are collected and then tagged with a radioactive substance.  These same cells are then injected back into you and a scan will look at where the radioactive cells ran to in your body, hopefully highlighting areas of activity and inflammation.

Endoscopic Ultrasound

This is also a newer, less common test that basically attaches an ultrasound to the probe that is used in different types of endoscopy.  This permits the doctor to visualize all of the layers of the GI tract, allowing them to see fistulae and identify where they have attached to in the body.

Interested in more information on IBD?

Next: How is IBD Treated?

Or refer back to the IBD Info Hub.


Trivia and Terminology:

Upper Endoscopy is also called EGD, which stands for Esophagogastroduodenoscopy

A combination of the tests discussed in this section are typically required for an accurate diagnosis

Fissures  are caused by inflammation that eats away through all of the layers of the intestinal tissue, top to bottom

Fistulas occur when fissures cause that tissue to latch on to other areas of tissue, which could be the intestine or other parts of the body

Abscesses form when a fistula latches onto an open area, such as the abdomen or the outside skin

String Sign is a term used to describe a result on a barium test that shows that the intestine has become so thick in areas that there is barely a ‘string’ of movement through it

Pseudopolyps are the little pieces of intestinal tissue that are trying to heal from inflammation, so they bulge upwards in comparison to the rest of the tissue that is still inflamed

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