The full blood count (FBC) is a common test that can help to diagnose a wide range of illnesses, infections and diseases. The doctor, nurse or technician takes a blood sample from you using a needle inserted into a vein in your hand or the crook of your elbow.
The blood sample is collected inside a special vial that contains a chemical to prevent the blood from clotting. The sample is sent to a laboratory and put into a machine for analysis.The FBC test looks for abnormalities in your blood, such as unusually high or low numbers of blood cells. If an abnormality is found, your doctor will usually arrange further tests to find the cause of the abnormality.