Bowel cancers and polyps can sometimes bleed, which is why screening looks for blood in your bowel. Occult blood means blood that is not visible to the eye and the faecal occult blood (FOB) test is a way of detecting tiny amounts of 'hidden' blood in your bowel motions.
The test doesn't tell you if you have bowel cancer, or a polyp, but if you have blood in your bowel motions you may be offered further tests, such as a colonoscopy, to find out the cause of the bleeding.
If you are sent an FOB test kit and you aren't sure whether you should do the test or not, you should call the freephone helpline number, which is on the letter that comes with the test.
You don't have to take part in the bowel cancer screening programme. If you don't want to take part you can simply choose not to complete and return the FOB test kit, or you can contact the freephone number on the letter to let the programme know that you don't want to participate.