How Is Crohn’s Disease Diagnosed?

Crohn’s disease is a form of inflammatory bowel disease (IBD) that causes inflammation in your gastrointestinal (GI) tract that can affect the small and large intestines. This inflammation results in symptoms like diarrhea, abdominal pain, weight loss, and anemia, among others.

Diagnosing Crohn’s disease can sometimes be difficult. This is because the condition can mimic symptoms of other digestive conditions, like ulcerative colitis—a condition that causes inflammation of the colon. That said, healthcare providers may use a variety of tests to rule out other conditions and confirm a Crohn’s disease diagnosis.

Common testing measures for Crohn’s disease include a physical exam, imaging tests, blood tests, and an analysis of your stool sample. A gastroenterologist, or a doctor who specializes in the digestive system, will usually perform these tests. They may also work with a radiologist, or a doctor with expertise in medical imaging techniques.

Physical Exam

During your initial appointment with a healthcare provider, you will likely undergo a physical exam. While a physical exam alone cannot diagnose you with Crohn’s disease, it can give your provider a better understanding of your symptoms and how to move forward with testing. 

As part of your physical exam, your healthcare provider may: 

• Ask if you have been experiencing fatigue or weakness
• Monitor your vitals (e.g., heart rate, temperature, blood pressure)
• Make note of any sudden, unintentional weight loss 
• Press on your abdomen for signs of bloating, pressure, or pain 
• Check your right lower quadrant of the abdomen for tenderness or masses

Your healthcare provider may also ask about your personal and family medical history, eating habits, and lifestyle to learn more about your symptoms. 

Endoscopies

An endoscopy is a type of imaging test that allows healthcare providers to take a closer look at the inside of your esophagus, stomach, and intestines. This test requires the use of an endoscope—a thin, long tube that is attached to a tiny camera and light. Currently, an endoscopy is the most accurate diagnostic tool healthcare providers have to diagnose Crohn’s disease.

There are different types of endoscopies, which include:

• Upper endoscopy and enteroscopy: During an upper endoscopy, your healthcare provider will insert the tube in your mouth and down your throat to view the upper end of your GI tract, including your esophagus, stomach, and small intestine. Your medical care team will usually give you an anesthetic liquid to drink to help numb your GI tract and make it easier for the tube to move down your esophagus. 
• Colonoscopy: A colonoscopy looks at the other end of your GI tract. During this procedure, your healthcare provider will insert the endoscope into your anus to look at your large intestine, which includes the colon, rectum, and anus. At this time, your healthcare provider may also take a biopsy or small tissue samples by scraping the surface of your intestines for further testing. 
• Capsule endoscopy: This procedure uses a different type of camera to show footage of your GI tract. Rather than the insertion of a tube, your healthcare provider will give you a small pill-sized capsule that contains a camera inside to swallow. As the capsule moves through your GI tract, the camera will take images of your digestive system and send it to an external receiver where your healthcare provider can look at the photos. If your provider uses this test, they will ask you to refrain from eating and drinking before your appointment. 

Other Imaging Tests

Other imaging tests can help your healthcare providers evaluate your intestines in a less invasive way than endoscopies. Alternatives for endoscopies include: 

• Small bowel magnetic resonance enterography (MRE): Rather than the insertion of a camera to take photos, this procedure uses a magnetic resonance imaging (MRI) machine to take detailed images of your intestines and check for signs of inflammation. Before the test begins, your medical team will give you a contrast solution mixed with colored dye to drink. They will also hook you up to an IV to give you fluids and more contrast solution. The contrast solution helps your provider clearly see inflammation on the images that the MRE produces.
• Computed tomography enterography (CTE) scan: A CTE scan is a type of X-ray healthcare providers use to produce images of your intestines. For small intestine CTE scans, your healthcare provider will give you contrast solutions, which are given by mouth and injected intravenously through an IV. Just like an MRE, the contrast solution helps your provider look for inflammation, as well as bleeding or other damage to your intestines.
• Upper GI and small bowel series: A type of X-ray imaging test that uses chalky white liquid made of barium to help coat the walls of your intestines. The coating helps the X-ray machine detect your intestines and allows your provider to see how the barium moves through your GI tract. It can take anywhere from two to five hours for the barium to move through your digestive system. During this time, the X-ray machine will take images of your intestines, which can help your provider look for signs of inflammation.

Blood Tests

Your healthcare provider may order blood tests to check for changes in red and white blood cells. Blood tests don’t detect Crohn’s disease by themselves, but can help your provider understand if you have any underlying health concerns of if and how Crohn’s disease is affecting your body. Complete blood counts, or CBC tests are the most common type of blood tests your provider may use.

In some cases, your provider may elect to order a blood test that checks for C-reactive protein (CRP)—a type of protein that is made by your liver and later released into your blood which can measure the amount of inflammation you have in your body. People with Crohn’s disease typically have high levels of CRP.

Stool Tests

Stool tests can be useful to detect the presence of blood, bacteria, and proteins in your intestines and rule out other digestive conditions. In most cases, you will collect your stool specimen at home and then drop it off at a lab, or you will collect and submit your stool at a lab. 

Your healthcare provider can perform one or both of these types of stool tests:

• Inflammatory marker testing: The most common type of inflammatory stool test is the fecal calprotectin test, which checks for calprotectin—a protein that activates in your white blood cells when your intestines become inflamed. 
• Pathogen testing: Pathogen testing looks for bacteria and parasites. This test can help your provider rule out bacterial or parasitic infections as the cause of your symptoms. 

Screening for Related Conditions

Other digestive-related conditions can also produce symptoms of Crohn’s disease, such as stomach pain or difficulty using the restroom. For this reason, your provider may also test for the following conditions during your diagnostic process:

• Ulcerative colitis
• Infectious colitis
• Diverticular colitis
• Celiac disease
• Irritable bowel syndrome
• Lactose intolerance
• Appendicitis
• Bowel cancer 
• Stomach flu and other viral infections

A Quick Review

Crohn’s disease is a chronic inflammatory bowel disease that affects your intestines and causes uncomfortable symptoms like diarrhea, abdominal pain, and weight loss. Receiving a diagnosis of Crohn’s disease can be difficult at first, especially because symptoms can mimic other conditions. 

If you suspect you have symptoms of Crohn’s disease or a similar digestive issue, it’s good practice to get tested. Your healthcare provider can use a variety of tests including a physical exam, several types of endoscopies, other imaging tests, blood tests, and stool tests to rule out other conditions or confirm a Crohn’s disease diagnosis. 

Getting tested early can help minimize frustrating symptoms and get you started on treatment sooner. In doing so, you may also notice an improvement in your quality of life.