Hepatitis B surface antigen, HBsAg (screening test)

HBsAg (Hepatitis B Surface Antigen) is the primary screening test used to detect infection with the Hepatitis B virus (HBV). HBsAg is the first viral marker to appear in the bloodstream after infection and indicates the presence of the virus in the body.

HBsAg testing is used to detect both acute and chronic hepatitis B infection, to screen individuals at increased risk, and to evaluate patients before medical procedures or during pregnancy. A positive result requires additional testing to confirm the diagnosis and assess the stage of infection.

Indications

• screening for hepatitis B virus infection;
• evaluation of individuals with risk factors for hepatitis B;
• before surgery or other invasive medical procedures;
• during pregnancy, according to medical recommendations;
• following accidental exposure to blood or potentially contaminated biological material;
• evaluation of patients with signs or symptoms suggestive of viral hepatitis.

Method

Qualitative determination of the Hepatitis B Surface Antigen (HBsAg) in venous blood using an immunological assay.

Procedure

A venous blood sample is collected, and the laboratory determines the presence or absence of HBsAg. The result is reported as reactive (positive) or non-reactive (negative) and is interpreted by the physician in the clinical context and, when necessary, together with other hepatitis B markers.