Fecal Immunochemical Test

Screening for Colon Cancer and Blood in Stool with FIT

A fecal immunochemical test (FIT) is a type of fecal occult blood test that screens for colon cancer by using antibodies to detect the presence of human hemoglobin, or blood, in the stool. This blood in the stool cannot be seen by the naked eye and is therefore called occult blood. FIT is a newer technology, in the past tests such as FOBT or iFOBT have been employed, but have been largely replaced by FIT testing or colonoscopy.

Experts recommend that patients at risk for colon cancer have their stool tested regularly to ensure early detection of internal bleeding inside the GI tract. Normal frequency of fecal testing is usually defined as 1 or 2 times a year in patients over 50 years of age. Patients who have a medical history of colon polyps or colon cancer in their families should also screen regularly and might have to start at a younger age, as deemed by a medical professional. People who should not use a fecal immunochemical test include patients who are bleeding already as a result of hemorrhoids or anal fissures, patients who detect blood in their urine and women who are in the middle of their menstrual periods or have completed their menstrual periods within 3 days.

The medical facility you select to test your stool sample will give you a special kit for at-home stool collection, which includes a brush tool and collection cards. The kits are small and portable, so you’ll be able to take them with you when you leave the house. Before a bowel movement, flush the toilet to reduce the risk of false-positive results. After relieving yourself, use the brush tool provided to scrap your stool for several seconds, allowing fecal matter to be collected on the brush. You may have to gently shake the tool after collection to remove any toilet water or excess stool before applying the sample to designated area on the collection card. Instructions on how to dispose of the brush and other materials should be included in the kit. This process of at-home stool collection may need to be repeated several times before a laboratory technician can analyze the results, so be sure to store the collection cards in a safe place, preferably in a location without excess heat, light and chemicals.

Also be sure to note if you experience bleeding, diarrhea or constipation during the test period—your doctor will need this information in order to provide accurate results. Although positive results of a fecal immunochemical test do not always conclude that a person has colon cancer, negative results also fail to provide definite assurance that a person is unaffected. Thus, there are several pros and cons to FIT.

Advantages of Fecal Immunochemical Test

Much like a fecal occult blood test (FOBT), a fecal immunochemical test is relatively cheap, painless and safe. However, fecal immunochemical testing is a more modern method than the traditional fecal occult blood test, FOBT or smear test. Accordingly, the test is more sensitive than FOBT and can detect bleeding from locations higher up the GI tract, such as the stomach. The process of collecting a stool sample for a fecal immunochemical test is also different from that of FOBT and is reportedly more appealing to patients. For example, there are no dietary restrictions implemented on the patient before the collection of stool.

Disadvantages of Fecal Immunochemical Test

Unfortunately, like FOBT, fecal immunochemical testing is still not the best way to detect abnormalities present in the gastrointestinal (GI) tract. While FIT can monitor conditions such as ulcerative colitis, additional testing would be needed to detect pre-cancerous polyps or pouches in the colon. The test produces false-positive results quite often and is only a preliminary step in detecting colon cancer and other problems.

Additionally, FIT testing should never be performed as a stand alone screening test.  The recommendations from the American Society of Gastrointestinal Endoscopists (ASGE) states that patients who opt for FIT testing should have annual FIT testing and a minimal of a flexible sigmoidoscopy every 5 years in addition.