Hepatitis B Surface Antigen Test (HBsAg)

This test screens for the hepatitis B surface antigen (HBsAg), the earliest and most reliable blood marker of an active hepatitis B virus (HBV) infection. It is suitable for anyone who wants clarity on their hepatitis B status, including people with symptoms such as fatigue, jaundice or abdominal discomfort, individuals with known exposure to the virus, those beginning a new relationship or planning pregnancy, and anyone undergoing routine sexual health screening. A simple blood sample is analysed in the laboratory using a validated immunoassay technique to detect the presence of the surface antigen.

What is screened

• Hepatitis B surface antigen (HBsAg): The primary marker used to identify an active or chronic hepatitis B infection. A positive result indicates that the virus is present in the blood and that the individual may be able to pass the infection to others. A negative result generally means no active infection was detected at the time of testing.

Why it matters

Hepatitis B is a viral infection that can quietly damage the liver over many years if left undiagnosed. Early detection through HBsAg screening allows timely medical review, appropriate monitoring of liver health, and access to treatment that can reduce the risk of long-term complications such as cirrhosis and liver cancer. It also helps break the chain of transmission by identifying people who may unknowingly pass the virus to partners, household contacts or, in the case of pregnancy, to a newborn baby. Knowing your status puts you in control and enables you to make informed decisions about your health and the health of those around you.

• Hepatitis B surface antigen (HBsAg)

No special preparation required.

For blood tests, we recommend drinking plenty of water beforehand to ensure smooth sample collection. If you are taking any regular medication, continue to do so unless advised otherwise by your doctor.