Fecal Immunochemical Test (FIT)
The fecal immunochemical test (FIT), also called an immunochemical fecal occult blood test (iFOBT), is a newer kind of stool test that also detects occult (hidden) blood in the stool. This detection is important because it can be a sign of precancerous polyps or colon cancer. Blood vessels at the surface of larger polyps or cancers are often fragile and easily damaged by passing stool. The damaged blood vessels usually release a small amount of blood into the stool, but only rarely is there enough bleeding to be visible in the stool, which is why these tests are helpful.
The FIT is done essentially the same way as the traditional guaiac FOBT, though some people may find it easier since there are no drug or dietary restrictions. Since vitamins and foods do not affect the FIT, sample collection may take less preparation. There are many varieties of FIT tests with varying levels of sensitivity, and depending on which you have, it may require as few as one stool sample, instead of three, like a guaiac FOBT. This test is also less likely to react to bleeding from parts of the upper digestive tract, such as the stomach, which is beneficial in increasing accuracy.
Part of the beauty of this test is that there is no preparation needed. You simply need to get the kit from your doctor and take the sample!
We realize this test isn’t going to be the most enjoyable experience. But there are a few ways to make your testing a little easier. First, have all of your supplies ready and in one place. Supplies will include a test kit, test cards, long brushes, waste bags and a mailing envelope. The kit will give you detailed instructions on how to collect the stool specimen. Always follow the instructions on your kit, but typically your test will instruct you to:
- Flush the toilet before beginning. After your bowel movement, place used toilet paper in the waste bag from the kit, not in the toilet.
- Brush the surface of the stool with one of the brushes and then dip the brush in the toilet water. Dab the end of the brush onto one of the slots in the test card or slide.
- Close the slot and put your name and the date on the test kit.
- Repeat the test on your next bowel movement, if instructed. Most tests require collecting more than one sample from different bowel movements. This improves the accuracy of the test because many cancers don't bleed all of the time, and blood may not be present in all stool samples.
- Place the test kit in the mailing envelope provided and return it to your doctor or lab as soon as possible (but within 14 days of taking the first sample).
For the FIT, a positive result indicates abnormal bleeding in the lower digestive tract. Since this test detects only human blood, other sources of blood, such as from the diet, do not cause a positive result.
For more information about FIT, please call the Colon Cancer Alliance’s Toll-free Helpline at (877) 422-2030.