Test ID: HBAGP
Hepatitis B Surface Antigen Prenatal, Serum
Useful For 
Suggests clinical disorders or settings where the test may be helpful
Stand-alone prenatal screening test for chronic hepatitis B carriage in pregnant women
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
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.
Hepatitis B surface antigen (HBsAg) is the first serologic marker appearing in the serum at 6 to 16 weeks following exposure to HBV. In acute infection, HBsAg usually disappears in 1 to 2 months after the onset of symptoms. Persistence of HBsAg for more than 6 months in duration indicates development of either a chronic carrier state or chronic HBV infection.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Negative
See Viral Hepatitis Serologic Profiles in Special Instructions.
Interpretation Provides information to assist in interpretation of the test results
A confirmed positive result (reactive screening test and confirmed positive hepatitis B surface antigen [HBsAg] confirmation test; see Method Description) is indicative of acute or chronic hepatitis B virus (HBV) infection.
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 antigen and/or detectable HBV DNA.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
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 antihepatitis 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
-Cadaveric specimens
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
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
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