Reviewed by: HU Medical Review Board | Last Reviewed: January 2018. | Last updated: November 2021
Stool tests are an important tool for assisting healthcare providers in determining if a person’s symptoms are being caused by inflammatory bowel disease (IBD), such as Crohn’s disease (CD) or ulcerative colitis (UC). Stool tests provide useful information, but they cannot be used alone to diagnose IBD. For this reason, results of stool tests are used together with the results of physical examination, blood tests, and diagnostic procedures including endoscopy and imaging.
What happens during a stool test?
To carry out a stool test, patients are asked to provide a stool sample for analysis.1-3 Healthcare providers will advise patients about the best way to go about collecting the sample. Usually, a collection container is sent home and is returned by the patient to the lab. After the sample is collected, a small smear of the stool is examined under a microscope.
What kinds of information can a stool test provide?
Stool tests can play different roles in helping healthcare providers make a diagnosis of IBD.3,4 The results of the tests can signal the presence of bleeding or inflammation in a person’s digestive tract, which may be caused by IBD. Another important way the tests are used is to find out if a person’s symptoms, such as diarrhea, are being caused by something other than IBD.
Common types of stool tests used to aid in diagnosing IBD are:
- Fecal occult blood test
- Stool culture
- Ova and parasites test
What is a fecal occult blood test?
A fecal occult blood test is used to detect hidden blood in the stool that is not easily visible.5 The presence of blood in the stool indicates that there is some type of bleeding occurring in the colon, but there are many conditions that can cause bleeding in the digestive tract, including diverticulitis, polyps (small growths), colon cancer, hemorrhoids or ulcers. Polyps and colorectal cancer can cause some of the same symptoms as CD and UC, such as:
For this reason, healthcare providers often use fecal occult blood testing as an early screening technique for colorectal cancer. Fecal occult blood tests are also used in the process of diagnosing other conditions, like IBD.5
What is a stool culture?
Stool culture tests can reveal intestinal infections that have similar symptoms to IBD. For example, a certain type of bacteria called the “Clostridium dificile” (or C. diff for short) toxin causes a major intestinal infection with symptoms including:6,7
- Loss of Appetite
- Abdominal pain or tenderness
How can stool tests detect signals of inflammation?
Stool tests can also detect certain proteins that can signal the presence of active inflammation in the digestive tract.3 These proteins are called “calprotectin” and “lactoferrin.” If the results of a stool test show an elevated level of these proteins, it suggests that there is inflammation that may be caused by IBD. To find out more, healthcare providers will usually suggest further diagnostic testing to determine the specific cause.
What is an ova and parasites test?
The ova and parasites stool test is another type of stool test is used to rule out different types of infections as the cause of a person’s symptoms, particularly diarrhea.2,3 The test is used to detect the presence of parasites or eggs (ova) that can be signs of intestinal infections with symptoms that are similar to those of IBD.2