The FOB and FIT tests

The faecal occult blood (FOB) test and faecal immunochemical test (FIT) can detect tiny amounts of hidden blood in your poo. The FIT test is being introduced in Scotland, and is sometimes used in Wales and Northern Ireland.

Once you reach bowel screening age, you will be sent a home screening kit. You will be asked to collect three poo samples from three different days. The FIT test only asks you to collect one sample.

It can take up to two weeks to get the results of your FOB test. If you feel anxious when waiting for your results, you could talk to a relative or close friend. There are three possible test results:

  • Normal – no blood has been found and you don’t need more tests.
  • Abnormal – blood was found and you may need more tests. It doesn’t mean you have cancer.
  • Unclear – some blood was found, but not enough for an abnormal result. You may be asked to repeat the screening test.

You can choose whether to take part in bowel cancer screening.

What is the FOB test (faecal occult blood test)?

The FOB test can detect tiny amounts of hidden blood in your poo. ‘Occult blood’ means blood you can’t see.

Bowel cancers and polyps sometimes bleed. But there can be other causes for blood in poo. If your FOB test finds blood, you will be offered another test to find the cause of the bleeding. This is usually a test called a colonoscopy.

The FOB test kit

You will get an FOB home screening kit when you reach the age that bowel cancer screening starts.

The kit includes:

  • instructions
  • six cardboard sticks to collect the samples
  • a test card
  • a prepaid hygienic envelope to return the samples.

There are three sections on the test card. These are for poo samples from three different days.

If you have any questions about the sample collection, or have a disability that makes using the kit difficult, call your country’s helpline. If you need a new test kit, they can send you one:

  • In England call 0800 707 6060, Monday–Friday, 9am–5pm.
  • In Scotland call 0800 0121 833, Monday–Friday, 8am–5pm.
  • In Wales call 0800 294 3370, Monday–Friday, 8am–5pm.
  • In Northern Ireland call 0800 015 2514, Monday–Friday, 9am–5pm.

If you live in England, you need to complete the test card and return it within 14 days of taking the first sample. In the rest of the UK, you have 10 days to return the card after taking the first sample. You’ll get a reminder after about four weeks if you don’t return the test kit.

If you decide not to take part in the screening programme, you can choose not to respond. Or you can contact your country’s helpline to tell them you won’t be sending your kit back.

FOB test results

You should get a letter with the results of your FOB test within two weeks. Your GP will also get a letter.

You could talk to a relative or close friend if you feel anxious when waiting for your results. Or, if you prefer, you can talk to one of our cancer support specialists on 0808 808 00 00.

There are three possible FOB test results:

  • normal
  • abnormal
  • unclear.

Normal result

About 98% of people (around 98 out of 100) have a normal result.

This means no blood was found and you don’t need any more tests. You’ll get an FOB test kit again in two years’ time, if you’re still within the age range.

Go to see your GP if you have any symptoms that could be bowel cancer before your next screening test. Don’t wait for a test invitation.

Abnormal result

Around 2% of people (about 2 in 100) have an abnormal result.

This means blood was found in your test result. But it does not mean you have cancer. Only about 1 in 10 people with an abnormal result have cancer.

Blood in poo can be caused by bleeding from small non-cancerous growths in the bowel called polyps. It can also be caused by other conditions, such as piles (haemorrhoids).

You will be offered an assessment and probably a bowel test called a colonoscopy.

Unclear result

A small number of people may have an unclear result. This means there was some blood detected, but not enough to give an abnormal result.

Having an unclear result doesn’t mean you have bowel cancer. It just means that you need to do a second test to check for blood in your poo. You will be sent another home screening kit. Most people who do this test get a normal result.

If the results of further tests are unclear or abnormal, you will usually be offered a colonoscopy. If the result of your second test is normal, you may be sent another kit to confirm the result.

Other reasons you may be asked to repeat the FOB test are:

  • Technical failure – Sometimes there’s a technical problem when your samples are tested in the laboratory. You’ll be sent a letter and another test kit to collect more samples if this happens.
  • Spoilt kit – Sometimes the FOB kit can’t be tested in the laboratory because it hasn’t been used properly or has been damaged. If this happens, you’ll be sent a letter and a replacement kit.

What is the FIT (faecal immunochemical test)?

The screening service in Scotland is changing to a new type of FOB test called the FIT test. This will happen over the next few years. For the FIT test, you only need to collect one sample of poo to be checked. The FIT test is also used in Wales and Northern Ireland for people who have an unclear result from their first FOB test.

Back to Bowel screening

Bowel scope screening

This test looks at the lower part of your large bowel. It can help find cancer at an early stage.


A colonoscopy is a test that looks at the inside of the large bowel.

Virtual colonoscopy

This test is also called a CT colonography. It uses a CT scanner to build a picture of the bowel.