Blood Tests (Phlebotomy)

A blood test involves a sample of blood taken for testing 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 or to check your blood count plus vitamin levels.

How is a blood test carried out?

  • A blood test usually involves attaching a tourniquet and then gently placing a needle attached to a syringe into one of the veins on the inside of your elbow or wrist.
  • You will feel a sharp prick as the needle goes in but this is not particularly painful.
  • A sample of blood is then taken and the needle is removed.
  • You will be given a cotton-wool pad to put pressure on the site of the injection, which stops any bleeding and should prevent bruising but this can occasionally occur.
  • Most blood tests only take a few minutes to complete.

Some blood tests require several samples taken over a period of time. For example, they may be done to check how you respond to a glucose load for instance. The results can help detect health problems in early stages, when treatments or lifestyle changes may work best.

Your doctor may consider other factors to confirm a diagnosis including; your signs and symptoms, your medical history, your vital signs (blood pressure, breathing, pulse, and temperature) and results from other tests and procedures.