The HBsAg (Hepatitis B Surface Antigen) CLIA Method is a laboratory test used to detect the presence of Hepatitis B surface antigen (HBsAg) in the blood using the Chemiluminescence Immunoassay (CLIA) method. CLIA is a highly sensitive and accurate testing technique that uses a chemical reaction to produce light, which is then measured to quantify the presence of the antigen.