At a glance
Also known as
FOB; FOBT; Faecal occult blood
Why get tested?
Faecal occult blood testing (FOBT) is used to screen for bleeding from the gut/intestine, which may be an indicator of bowel cancer
When to get tested?
FOBT is offered as a screening test for the early detection of bowel cancer in patients without symptoms of bowel cancer. The National Health and Medical Research Council (NHMRC) recommend screening with FOBT for people from the age of 50, every 2 years. Patients with symptoms of bowel cancer should speak to their doctor regarding the most appropriate further investigations (e.g. colonsocopy)
One or more stool/faecal samples. Usually two samples less than two days apart
What is being tested?
The faecal occult blood test (FOB) checks for small amounts of blood (not visible by eye) in your stool. Normally, there will not be enough blood lost through the gastrointestinal tract (stomach and intestines) to turn an FOB positive or for you to notice it by looking.
A positive FOB will tell your doctor that you have bleeding occurring somewhere in your gastrointestinal tract. This blood loss could be due to ulcers, diverticulosis, bleeding polyps, inflammatory bowel disease, haemorrhoids (piles), from swallowed blood due to bleeding gums or nosebleeds, or it could be due to or .
Anything that sticks out into the intestine, like a polyp or tumour, and is rubbed against by the faeces as it passes through, has the potential to bleed now and again. Often this small amount of blood is the first, and sometimes the only, of early bowel cancer, making the FOB a valuable screening tool.
How is the sample collected for testing?
Older types of FOB tests (Guaiac test) required dietary restrictions prior to testing (e.g. avoidance of red meat). These tests have largely been replaced with so-called immunochemical tests. These tests are more sensitive and specific (less and ) than the guaiac method and do not not require dietary restrictions. Be careful to follow you doctor’s instructions or the instruction included with the collection kit.
Your doctor or laboratory will give you a collection kit. You collect a separate sample from two different stools, preferably no more than 2 -3 days apart. The FOB test kit includes an instruction sheet that should be carefully followed on how to collect and store the samples. Usually you will collect all samples then return all of them to your doctor/laboratory at the same time, or by posting them in a package provided in the kit.