A blood test is when a sample of blood is taken for testing in a laboratory. Blood tests have a wide range of uses and are one of the most common types of medical test. For example, a blood test can be used to:
- assess your general state of health
- confirm the presence of a bacterial or viral infection
- see how well certain organs, such as the liver and kidneys, are functioning
A blood test usually involves the phlebotomist taking a blood sample from your arm. This is often known as venepunture. The usual place for a sample is the inside of the elbow or wrist where the veins are relatively close to the surface. Blood samples from children are most commonly taken from the back of the hand. The child's hand will be anaesthetised (numbed) with a special cream before the sample is taken.
If you are worried or concerned about the procedure please bring this to the attention of the phlebotomist before the procedure is carried out.
Remember, no one knows your body like you do and if you have a preference for which arm/vein the blood test is taken from, please express this to the phlebotomist at your appointment.
You can find out more about blood tests, their purpose and the way they are performed on the NHS Choices website.