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Hepatitis B virus (HBV) is endemic throughout the world. The infection is spread primarily through percutaneous contact with infected blood products (eg, blood transfusion, sharing of needles by intravenous drug addicts). The virus is also found in various human body fluids, and it is known to be spread through oral and genital contacts. HBV can be transmitted from mother to child during delivery through contact with blood and vaginal secretions, but it is not commonly transmitted transplacentally. Infection of the infant can occur if the mother is a chronic hepatitis B surface antigen carrier or has an acute HBV infection at the time of delivery. Transmission is rare if an acute infection occurs in either the first or second trimester of pregnancy.
Stand-alone prenatal screening test for chronic hepatitis B in pregnant women
A reactive screen result confirmed as positive by hepatitis B surface antigen (HBsAg) confirmatory test is indicative of acute or chronic hepatitis B virus (HBV) infection, or chronic HBV carrier state.
Specimens with initially reactive test results, but negative (not confirmed) by HBsAg confirmation test, are likely to contain cross-reactive antibodies from other infectious or immunologic disorders. These unconfirmed HBsAg-reactive screening test results should be interpreted in conjunction with test results of other HBV serologic markers (eg, hepatitis B surface antibody; hepatitis B core antibody, total and IgM).
The presence of HBsAg is frequently associated with HBV replication and infectivity, especially when accompanied by the presence of hepatitis B envelope (HBe) antigen and/or detectable HBV DNA.
This test is not offered as a screening or confirmatory test for blood donor specimens.
Not useful for diagnosis of hepatitis B during the "window period" of acute hepatitis B virus (HBV) infection (ie, after disappearance of hepatitis B surface antigen [HBsAg] and prior to appearance of hepatitis B surface antibody [anti-HBs]). Testing for acute HBV infection should also include anti-hepatitis B core IgM.
Confirmed positive HBsAg test results should be reported to the State Department of Health, as required by law in some states.
Individuals, especially neonates and children, who recently received hepatitis B vaccination may have transient-positive HBsAg test results because of the large dose of HBsAg used in the vaccine relative to the individual's body mass.
Performance characteristics have not been established for the following specimen characteristics:
-Grossly icteric (total bilirubin level of >20 mg/dL)
-Grossly lipemic (triolein level of >3,000 mg/dL)
-Grossly hemolyzed (hemoglobin level of >500 mg/dL)
-Containing particulate matter
See Viral Hepatitis Serologic Profiles in Special Instructions.
1. Badur S, Akgun A: Diagnosis of hepatitis B infections and monitoring of treatment. J Clin Virol 2001;21:229-237
2. Servoss JC, Friedman LS: Serologic and molecular diagnosis of hepatitis B virus. Clin Liver Dis 2004;8:267-281