How is IBD Diagnosed?

The path to receiving a Crohn’s disease or ulcerative colitis diagnosis can be overwhelming and even frightening at times. The best thing you can do during this time is be educated and prepared. We can help you understand the process of diagnosing inflammatory bowel disease (IBD), and the common tests and procedures your healthcare team may recommend you undergo. 

There is no single test to confirm a Crohn’s disease or ulcerative colitis diagnosis. Your healthcare providers should evaluate your current medical history and use information from diagnostic testing to exclude other potential causes of your symptoms, since IBD symptoms are often similar to other conditions. This may take time, but here is some helpful information and tips to better understand the testing and evaluation process.

Initial testing and evaluation

The first step to diagnosis and treatment is a standard physical exam of your body. Your doctor will speak to you and ask questions about your overall health, diet and nutrition, family history, and your daily routine.

Communication tips:

Daughter hugging senior mother; working on laptop together
  • If you have any previous labs/tests or medical records from previous consultations, it would be helpful to share that with your provider.
  • Consider bringing a trusted family member or close friend to your appointments. This may help ease your stress and help you later remember information from your doctor. You may also want to bring a notepad to jot down new terms, or the sequence of events laid out by your doctor.
  • Write down your symptoms and bring it to your appointments, so you don’t have to worry about forgetting anything important.
  • Contact your insurance to understand coverage and potential out-of-pocket costs. Each insurer is different, so your doctor may not know which tests your insurer will cover.

What tests are used to diagnose IBD?

  • Your doctor may order diagnostic tests to look for signs of IBD and rule out other possible medical conditions.
  • Your first tests will likely include laboratory tests of your blood and stool.
  • Further testing could include X-rays of the upper and lower gastrointestinal (GI) tract. Your doctor may recommend a test that uses a contrast chemical that helps your doctors see a clearer and more detailed picture of your GI tract.  

These tests are explained in greater detail below.

Blood and stool laboratory tests

Scientist handling blood samples

Physicians commonly use blood tests as part of your diagnostic work-up. Blood tests involve a blood draw from a vein in your arm. However, some tests (particularly for pediatrics) may be done from a fingerstick. 

To collect a stool sample, your healthcare provider will give you a stool collection kit along with specific instructions. 

Blood and stool analysis can determine if there is inflammation in the body. Although these tests will not reveal what’s causing the inflammation, they do serve as an indicator that the physician needs to perform other types of tests to identify the inflammation’s source. 

Proteins found in blood and stool, also called biomarkers, are measurable indicators of disease and may be useful tests for detecting inflammation. Biomarker tests may be more helpful for detecting flares and for guiding the right course of treatment and testing than for diagnosing IBD.

Blood biomarkers include C-reactive protein (CRP) and Erythrocyte sedimentation rate (ESR) which help detect systemic inflammation.

Fecal biomarkers include:

  • Fecal calprotectin is a protein that comes predominantly from neutrophils, a type of white blood cell that accumulate into intestines during inflammation. Measurement of fecal calprotectin is a useful marker of gastrointestinal inflammation that happens during IBD flare.
  • Fecal lactoferrin is another important but different protein than neutrophils. Measurement of fecal lactoferrin is a useful marker of gastrointestinal inflammation that happens during IBD flare.

Endoscopy and imaging

Surgeon holding endoscopy tool

Your doctor may recommend additional testing to look inside your GI tract. While these tests are more invasive and may sound scary, your healthcare providers will be careful to minimize any discomfort.

Your doctor may recommend an endoscopy – a procedure used to look inside the body – to get a detailed look at the inside of your colon using a small camera mounted to the end of a lighted tube. This is often performed in an outpatient setting. An endoscopy helps your physician see if inflammation is present, where it is located, assess its severity, and obtain biopsies to confirm your diagnosis. Endoscopies help monitor the effectiveness of your treatment; healing of the lining of the intestine (mucosal healing), which can be seen during an endoscopy, is a sign that your treatment is effective.

Endoscopies used in IBD testing include:

  • colonoscopy allows doctors to examine the colon, or large intestine, by inserting a flexible, lighted tube through the opening to your anus. The tube runs through the entire length of the colon and the end of the small intestine (terminal ileum). Typically, you will receive sedation prior to the procedure to minimize discomfort. 
  • An upper endoscopy lets doctors see the gastrointestinal tract from the top down, using a flexible, lighted tube that’s inserted through your mouth, down the esophagus, into your stomach and as far down as the duodenum (the first section of your small intestine). It is used in suspected or established Crohn’s disease cases to evaluate a wide variety of symptoms including, but not limited to, upper abdominal pain, nausea, vomiting, and difficulty swallowing.
  • A sigmoidoscopy allows doctors to examine the left side of the colon or rectum by inserting a flexible, lighted tube through the opening to your anus. A sigmoidoscopy can be a good diagnostic test to confirm the disease and to monitor your response to therapy. Because it is a very short procedure, it can be performed without sedation and is associated with less discomfort than a colonoscopy. Sometimes providers perform a sigmoidoscopy to evaluate the rectum for Crohn’s with a fistula near the anus.
  • A pouchoscopy is an exam used to evaluate the ileal (small bowel) pouch created after colon surgery in ulcerative colitis.
  • A video capsule endoscopy is performed by swallowing a small, pill-sized camera, which takes pictures of the small intestine and bowel as it travels through your GI tract. These pictures are stored in a recorder that you wear at the time of the pill ingestion until the study is complete which could be eight or 12 hours. The camera is later expelled during a bowel movement.

Certain endoscopies require bowel preparation. Talk to your healthcare team about ways to prepare and tips for making this preparation easier. Before your test, you will typically drink a preparation fluid that removes stool and debris by causing diarrhea. Follow the directions from the pharmacy closely. The preparation fluid may have an unpleasant taste. The colon preparation is time-consuming and can be uncomfortable; however, the result will be a clean intestine, with an unobstructed view of the intestinal lining.


Your doctor may take biopsies of your colon or another area of your GI tract while performing a colonoscopy or endoscopy. During the biopsy, a small piece of tissue is removed from the inside of the intestine for further testing.

  • Your biopsied tissue will be analyzed (reviewed) in a pathology laboratory and screened for disease. Biopsies are also used for colorectal cancer screening.
  • While a biopsy sounds scary, medical advances have made this procedure virtually pain-free.


Your doctor may want to use a chromoendoscopy during a colonoscopy to look for polyps or precancerous changes. A chromoendoscopy involves spraying a blue liquid dye into the colon to highlight and detect slight changes in the lining of your intestine, such as polyps (small clumps of cells). Polyps can then be removed and/or biopsied. It is common to have blue bowel movements following this procedure. 

Radiology scans or diagnostic imaging

Healthcare professionals examining scans on a screen

Traditional upper endoscopy and colonoscopy will not be able to reach about two-thirds of the small intestine. Therefore, in addition to capsule endoscopy, radiologic exams or diagnostic imaging are performed to evaluate these segments of intestines as well as to evaluate areas outside the bowel.


X-rays are the oldest way of imaging the inside of the body. X-rays are cost-effective and useful for detection of blockages in the small or large intestine. Patients with Crohn’s disease, for example, can have inflammation and/or scarring of the small bowel that narrows the intestine and prevents the easy passage of stool and air.

Barium Contrast Studies

Barium studies use contrast material (barium) with traditional X-ray technology. Barium is a chalky/milky liquid that the patient drinks prior to the procedure. A series of X-rays are taken to observe the material flowing through the digestive system. These studies include:

Upper gastrointestinal (GI) series examines the esophagus, stomach, and first part of the small bowel (duodenum) for patients with Crohn’s disease 

Small bowel series and small bowel enteroclysis examines the entire small bowel. For a small bowel series, you will drink several cups of barium, and then have an X-ray taken every 15–30 minutes as the barium travels down the small intestine and enters the large intestine. The time required is variable, but may be take four to five hours. An enteroclysis is similar, except that the barium is placed directly into the small intestine through a tube in the nose or mouth. 

Lower GI series involves inserting the contrast material directly into the rectum (barium enema) and provides images of the colon or large intestine. During the exam, the colon is distended with air to provide better images. 

Cross-sectional imaging

Cross-sectional imaging is comprised of computed tomography scanning (CT scan) and magnetic resonance imaging (MRI). These techniques are extremely helpful in diagnosing and managing IBD. They can evaluate the entire thickness of the bowel wall and can detect inflammation and complications such as fistulas, abscesses, and obstructions.

CT scan, also known as a CAT scan, takes simultaneous X-rays from several different angles to reconstruct a realistic image of the internal organs. The CT scan is used to rule out complications of IBD, such as intra- abdominal abscesses, strictures, small bowel obstructions or blockages, fistulas, and bowel perforation. 

CT enterography (CTE) is a variation of a CT scan. During this exam, a special oral and/or intravenous contrast agent is given to better outline the intestines. In addition, CTE reconstructs images in 3-D to better visualize the small bowel in relation to other organs. The physician may suggest this exam to identify areas of inflamed bowel and more subtle obstructions or blockages.

Magnetic resonance enterography (MRE) is a special MRI study that looks more closely at the small intestine. An MRE is different than the CTE because it doesn’t involve radiation. During the MRE, you will be asked to drink contrast that helps distend the small intestine. You will also be given a contrast agent through an IV. Both the oral and IV contrast help determine if inflammation or changes are old versus new, if narrowing (strictures) are present, if abnormal connections are present (fistulas), or if there are abscesses. The MRE can also help clarify the length, extent, and severity of small bowel disease.

Magnetic resonance cholangiopancreatography (MRCP) is a specialized MRI exam that provides a view of the bile ducts, gall bladder, liver, and pancreas. This test is helpful in diagnosing primary sclerosing cholangitis (PSC) in IBD patients, a condition characterized by severe inflammation and scarring in the bile ducts.

Managing inflammatory bowel disease

Managing IBD requires proactive care. Successful disease management begins with receiving an accurate diagnosis. Diagnostic testing will help your healthcare provider identify the extent of disease as well as its precise location in the gastrointestinal tract to help select the most effective therapies for your IBD. For more information about diagnosis and monitoring, view our comprehensive brochure, Diagnosing and Monitoring IBD. You can also check out our Newly Diagnosed page for tips and resources.