It can be a challenge to get a Crohn’s disease diagnosis. There isn’t a single test that can confirm Crohn’s.
Your primary care physician and gastroenterologist will examine family history, special tests, and more to try and confirm a Crohn’s disease diagnosis. However, even with a full battery of tests, it can be impossible to distinguish Crohn’s from diseases with similar symptoms, such as ulcerative colitis. In these instances, it is possible to have a diagnosis of: indeterminate colitis.
In addition to confirming a Crohn’s disease diagnosis, the doctors will work to determine which parts of the digestive tract are impacted.
Tests used to get a Crohn’s disease diagnosis
In addition to reviewing your medical and family history and performing a physical exam, your doctor may use a combination of tests to determine if you have Crohn’s. Some require samples, such as blood or stool, while others are invasive (performed inside your body).
If you believe that you are, or may become, pregnant, it is important to inform your physician.
Blood tests are a common part of a traditional “work-up” and are considered routine. Typically drawn through a vein in the arm (venipuncture), blood can be drawn in the practice or at an outside laboratory.
When analyzing blood, clinicians are looking for signs of inflammation or anemia. If inflammation is detected, clinicians will schedule other tests to try and determine the reason. Anemia is a condition where the blood does not have enough red blood cells – leading to reduced oxygen flow. Among Crohn’s patients, anemia is commonly caused by blood loss (which leads to an iron deficiency) or vitamin B12 deficiency (usually caused by ileal disease).
A common blood test is a complete blood count (CBC). In addition to providing information on anemia and inflammation, it can identify infection and monitor certain medications. It is often conducted regularly over time.
Stool (feces) tests are often used to rule out other diseases and to monitor for blood that may be difficult to detect.
Other gastrointestinal infections with similar symptoms that can be ruled out are:
- C. difficile
- E. coli
You may be familiar with x-rays if you have broken a bone (or seen any medical shows on television). X-rays use a bit of radiation to present images of the inside of a human body. However, they are limited because they typically “look through” soft tissues. This is why bones show up so clearly but organs do not. To overcome this, CT scans may be used, which are series of X-rays taken from many angles and then pieced by together to a view of the body.
If a traditional X-ray or CT scan is not clear, it is also common to use barium to improve the image quality. In a traditional X-ray, the GI tract would not be clearly visible as the X-rays would penetrate the structures. Barium helps with this.
X-rays may be done on the upper portion of the GI tract (called an “upper GI series”) – which requires a person to take by mouth a chalky fluid that contains barium. It is also possible to administer the barium fluid through the rectum (called a barium enema) to examine to lower portion of the GI tract.
How it works: As it passes through the intestine, the X-ray is conducted. The barium makes the intestines appear white on the X-ray film so doctors may examine the GI tract. With this test, a clinician may be able to see ulcers, portions of the intestine that are narrow, fistulae (“tunnels between” organs), and more.
Endoscopy & Biopsy
An endoscopy is a virtually painless, invasive test that uses modern technology to provide a view of the inside of the gastrointestinal (GI) tract. Endoscopies are often performed during outpatient visits.
A doctor will get views of the GI tract by using a small camera that is mounted on the end of a lighted tube. Often times, the tool will also have a method of gathering a small tissue sample, called a biopsy. Additional tests can be conducted on the cell tissue to hep with a diagnosis. There are different kinds of endoscopies based on what is being examined. 4 common ones for getting a Crohn’s disease diagnosis are:
- Goal: Examine the colon, the lowest part of the large intestine – looking for polyps or changes
- Method: Insert medical device through the anus
- Goal: Similar to a colonoscopy – looking for early or flat polyps that could be removed
- Method: Similar to colonoscopy except that a blue, liquid dye is used to help detect slight changes in the intestine lining.
- Goal: Examine the colon and rectum
- Method: Similar to a colonoscopy, through the anus, but with a shorter scope tool
- Upper Endoscopy
- Goal: Examine the mouth, esophagus, stomach, duodenum, and/or the beginning of the small intestine
- Method: Insert medical device through the mouth
New technologies are providing more comfortable methods for scoping the GI tract. One example of this is PillCam, a capsule that is equipped with a light and a camera. Taken by mouth, it captures images as it basses through your system. Some challenges of Crohn’s, such as narrow intestines or obstructions, may necessitate other options to avoid having issues with a capsule.
This is not an exhaustive list of tests to diagnose Crohn’s. Additional laboratory tests and imaging studies, including MRIs and fluoroscopic exams, are common.
For additional information, the Crohn’s and Colitis Foundation of America has valuable information on diagnosing Crohn’s and IBD.