About the FOB test  

The FOB test is a home test kit offered to all 60-74 year olds in England. It checks for the presence of blood in a stool sample, which could be an early sign of bowel cancer. If you are 75 or over, you can ask for this test by phoning 0800 707 60 60.

FOB stands for "faecal occult blood" ("occult blood" means "hidden blood"). It can detect tiny amounts of blood in your poo that you cannot normally see.

Why does the NHS offer FOB testing?

Regular bowel cancer screening using the FOB test has been shown to reduce the risk of dying from bowel cancer by 16%.

When are you offered the test?

Men and women in England are offered an FOB test every two years from the age of 60 to 74. As long as you’re registered with a GP and your GP has your home address, you should automatically be sent the home test kit by post.

People aged 75 and older can still be screened for bowel cancer. They can request an FOB screening kit by calling the freephone helpline on 0800 707 60 60.

What does it involve?

You carry out the FOB test in the privacy of your own home. The screening kit provides a simple way for you to collect small samples of poo, which you wipe onto a special card. You send this card in a hygienically sealed freepost envelope to the screening laboratory for testing. There are detailed instructions with each kit – read the kit instructions here (PDF, 374kb). If you have any questions about how to use the home test kit, you can call the helpline on 0800 707 60 60.

You may think that doing the test sounds a bit embarrassing or unpleasant, but it will only take a few minutes and is a good way of detecting bowel cancer early.

The FOB test does not diagnose bowel cancer, but the results will tell you whether you need an examination of your bowel (a colonoscopy).

FOB test results

You should receive a results letter from the laboratory within two weeks of sending in your sample. There are three types of results you could receive.

Most people will have a normal result

A normal result means that blood was not found in your test sample. Most people (about 98 out of 100) will receive a normal result. A small number of these people will have repeated the test because they had an unclear result previously.

A normal result does not guarantee that you do not have or will never develop bowel cancer in the future, so being aware of the symptoms of bowel cancer is still important.

A few people will have an unclear result

An unclear result means there was a slight suggestion of blood in your FOB test sample.

Receiving an unclear result does not mean you have cancer, just that you need to repeat the FOB test.

If you receive an unclear result, you will be asked to complete the FOB test up to twice more. This is necessary because polyps and cancers do not bleed all the time.

About 4 in 100 people will initially receive an unclear result. Most people who repeat the test will then receive a normal result.

A few people will have an abnormal result

An abnormal result shows that blood may have been found in your FOB test sample – it is not a diagnosis of cancer, but it does mean that you will be offered a colonoscopy. The abnormal result may have been caused by bleeding from bowel polyps, rather than a bowel cancer. It may also have been caused by other conditions, such as piles (haemorrhoids).

About 2 in 100 people doing the test will have an abnormal result. Sometimes, someone will have an abnormal result after their previous result was unclear.

If you receive an abnormal result, you'll be offered an appointment with a specialist screening practitioner at a local screening centre, to discuss having a more detailed examination of your bowel (a colonoscopy), to see whether or not there is a problem that may need treatment.

A colonoscopy uses a longer tube, which can look for polyps further up the bowel. 

What happens during the colonoscopy?

If polyps are found, most can be removed painlessly, using a wire loop passed down the colonoscope tube.

These tissue samples will be checked for any abnormal cells that might be cancerous.

  • About 5 in 10 people who have a colonoscopy will have a normal result (they do not have cancer or polyps).
  • About 4 in 10 will be found to have a polyp, which if removed may prevent cancer developing.
  • About 1 in 10 people will be found to have cancer when they have a colonoscopy.

A colonoscopy is the most effective way to diagnose bowel cancer. For most people, having a colonoscopy is a straightforward procedure.

However, as with most medical procedures, there is the possibility of complications. These can include heavy bleeding (about a 1 in 250 chance) that needs further investigation or medical advice. The colonoscope can cause a hole (perforation) in the wall of the bowel (about a 1 in 1,000 chance). In extremely rare cases, colonoscopy may result in death. Current evidence suggests that this may only happen in about 1 in 10,000 cases.

Remember: most people who complete the FOB test will not need a colonoscopy.

If you want to opt out...

If you don't want to be invited for bowel screening in the future, call the programme helpline on 0800 707 6060 and the staff will guide you through the opting-out process. If you change your mind at a later date, you can simply ask your GP to put you back on the list.

Frequently Asked Questions (FAQs)

Read some FAQs on the FOB test.


Page last reviewed: 09/02/2015

Next review due: 01/02/2018