Hepatitis B test

Blood test to detect hepatitis B infection

The hepatitis B blood test checks for a protein on the surface of the virus called hepatitis B surface antigen (HbsAg)

About hepatitis B test

A blood test can detect various parts of the hepatitis virus.

The hepatitis B test detects for a protein on the surface of the virus called hepatitis B surface antigen (HbsAg).

If you are found to be infected (if your test is HBsAg-positive), your consultant may recommend further tests.

Need to know

  • What happens during the test icon plus

    A tight band (tourniquet) may be put around your upper arm. This causes the vein to swell and makes it easier for a blood sample to be taken. Before taking the sample, your consultant may clean the area of skin with an antiseptic wipe.

    A syringe is used to remove a small amount of blood from your arm. You should only feel a pinprick as the blood is extracted. Pressure is applied using a cotton pad and a plaster may be put on the small wound.

    The sample can be taken by your consultant, or a nurse, or by other hospital staff, and the entire process will take only a few minutes.
  • How to prepare icon plus

    As this is a very simple procedure, there is usually no preparation required. You may be asked to avoid eating or drinking anything except water for up to 12 hours before your hepatitis B test. If you’re taking certain medication, you may also be advised to stop taking it for a while prior to the procedure.

    It's important to follow the instructions you're given, as not doing so may affect the results of the test and you may be required to reschedule to do the procedure again.

    Your consultant will explain the procedure and any instructions to you and answer any questions you may have.
  • After your test icon plus

    The procedure usually takes just a few minutes with little or no pain, and you should be free to go home immediately if you aren't feeling any after-effects like dizziness. Results should come back within a few days. 

    If your test result is HBsAg-positive, your consultant may advise further tests to:

    • assess how long you've had the virus and its activity (viral load)
    • screen for other infections such as hepatitis A, C, D and HIV, as co-infection can influence treatment options
    • find out if and how the virus is affecting your liver

    Your consultant will also answer any questions you may have.


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This content is intended for general information only and does not replace the need for personal advice from a qualified health professional.
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