What's a FIT test?
Fecal Immunochemical Test, or FIT, tests for microscopic traces of blood in your stool. It's a new and highly accurate test, and has two main purposes. The first is in bowel cancer screening, where you have no symptoms, and the second is to diagnose a condition based on bowel symptoms, for example, in inflammatory bowel disease (IBD) like Crohn's disease or ulcerative colitis (UC), or symptoms that could be bowel cancer. There can be lots of other causes for bleeding in the gut – some serious, some less so.
A positive test – that there is bleeding coming from somewhere in your gut – is used to then order further investigations that can pinpoint the cause of your symptoms, or determine whether this may be an early sign of bowel cancer.
It's important to emphasize that this is not a test for cancer or any other disease – it only tests for blood in the gut, and this could also be from hemorrhoids, a tear in the anus, a polyp, diverticular disease, or even bleeding from high up in the gut, like a stomach ulcer. It needs further investigations within context before a diagnosis can be made.
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What does the test involve?
You will receive a home test kit by mail, at your doctor's office, or from the pharmacy.
A small sample of poop is collected, placed in a container, and mailed to a lab for testing. Newer kits even provide results at home within minutes. Each kit has its own instructions, and many offer online support.
What does the result mean in bowel cancer screening?
A negative result makes bowel cancer, otherwise called colorectal cancer, highly unlikely. You will await your next screening test in one year, but if you have concerning symptoms in the meantime – a change to your bowel habits, new persistent diarrhea or constipation, weight loss, feeling very tired, or any iron deficiency anemia – then you should book an appointment with your doctor. Don't wait until your next screening.
With a positive result, your doctor will send you on a fast-track pathway to investigate this – you will be seen at the hospital within a couple of weeks. This team will likely order a blood test and a colonoscopy, where a tube with a camera is inserted into the rectum to visualize the bowel and take any tissue samples.
What does the result mean if I have symptoms?
As there will be a specific reason why your doctor requested this, it's best to catch up with them to explain the results and any next steps. A negative result simply means that no bleeding was detected in your bowel. Negative or positive, your doctor may suggest further investigations to determine the cause of your symptoms, or a trial of treatment.
Your doctor may suggest a blood test or a colonoscopy. For IBD, they may suggest another stool test, called a calprotectin test.
If your symptoms could be due to bowel cancer, even with a negative test, they may decide to refer you on the fast-track pathway anyway. They will use their clinical judgment.
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