Diagnostic Tests and Procedures
Currently, there is no single test that can be used to diagnose inflammatory bowel disease (IBD). The diagnostic process involves gathering various types of information about the patient’s condition, using a range of different tests and procedures. These may include:
Which laboratory blood and stool tests are commonly used to help diagnose inflammatory bowel disease?
Blood tests and stool tests can be used to detect signs of IBD and help to determine if a patient’s symptoms are linked to Crohn's disease (CD), ulcerative colitis (UC), or to some other cause.1-3 If a physical examination suggests that a person’s symptoms may be caused by IBD, then both blood and stool tests are usually recommended by healthcare providers.
These tests can both be used to check if there is active inflammation present in a person’s body, although the tests cannot tell for certain the cause of that inflammation. Elevated levels of proteins called “calprotectin” and “lactoferrin” in a stool sample can indicate the presence of inflammation. Blood tests used to detect inflammation include:
- The level of white blood cells
- C-reactive protein test (CRP)
- Erythrocyte sedimentation rate (ESR or “sed rate”)
Anemia (low red blood cells) is a common complication of IBD; blood testing can determine whether a person has anemia and if so, what the cause of the anemia is. Dehydration is very often caused by persistent diarrhea, a common symptom of IBD. It can be detected using a blood test to measure a person’s electrolyte levels.
One of the most important functions of laboratory stool testing is to find out whether a patient’s symptoms are the result of a serious infection or other condition, such as colorectal cancer. Fecal occult blood testing and stool culture, ova, and parasite testing are often used for this purpose.
How can diagnostic endoscopy procedures help to diagnose IBD?
Endoscopy procedures allow for the visual examination of the inside of the digestive tract.1,2 These tests use a tiny camera and light that are attached to the end of a thin, flexible tube that is inserted into the body through the mouth or the rectum.
A colonoscopy is the most common procedure used to diagnose IBD. This is because it allows viewing of the entire colon and the end of the small intestine, which are areas often affected by IBD. Upper endoscopy allows the upper part of the digestive tract to be examined, while flexible sigmoidoscopy focuses on the rectum and lower part of the colon.
Capsule endoscopy is a new technology in which a patient swallows a tiny camera that captures thousands of images as it travels through the small intestine, an area of the digestive tract that most other types of endoscopy cannot access.
What types of diagnostic imaging and scanning are used?
Together with laboratory testing and diagnostic endoscopy procedures, imaging and scanning can provide further information to give a clearer picture of a patient’s symptoms and their causes.1,2 Common types of diagnostic imaging for IBD are:
- Contrast radiography (small bowel series and barium enema)
- Computed tomography (CT) scan
- Magnetic Resonance Imaging (MRI)
These kinds of imaging tests can be used to identify the location and severity of inflammation in the patient’s digestive tract, as well as complications that may be caused by IBD.
How effective are diagnostic tests in diagnosing inflammatory bowel disease?
Generally, research suggests that using pairs of tests, rather than individual tests, are more effective and accurate in diagnosing active CD or UC.4,5 For example, one study reports that capsule endoscopy testing on its own is very accurate, but it is extremely accurate when combined with a colonoscopy. Similarly, capsule endoscopy and CT enterography are relatively good at detecting active CD as individual tests, but they are more sensitive when the two tests are combined.4