Hepatitis B Surface Antigen Test - Hepatitis B Surface Antigen (HBsAg) Test

This test detects the presence of hepatitis B virus surface antigen (HBsAg) in blood serum. HBsAg appears in the blood during the incubation period (before symptoms appear) and remains present throughout acute infection. If it persists for more than 6 months, it diagnoses chronic hepatitis B infection. The presence of HBsAg is conclusive evidence of active infection and the ability to transmit the virus to others. It is the primary test for identifying virus carriers.