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HelpTest Code HBNTP Hepatitis B Virus Surface Antigen Confirmation, Prenatal, Serum
Reporting Name
HBs Ag Confirmation Prenatal, SUseful For
Diagnosis of acute, recent, or chronic hepatitis B in prenatal patients
This test is not useful during the "window period" of acute hepatitis B (ie, after disappearance of hepatitis B virus surface antigen [HBsAg] and prior to appearance of HBs antibody).
This test is not suitable as stand-alone prenatal screening test of HBsAg status in pregnant women.
This test is not offered as a HBsAg screening or confirmatory test for blood donor specimens.
Method Name
Only orderable as a reflex. For more information see HBAGP / Hepatitis B Virus Surface Antigen Prenatal, Serum.
Electrochemiluminescence Immunoassay (ECLIA)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Serum SSTOrdering Guidance
Specimen Required
Only orderable as a reflex. For more information see HBAGP / Hepatitis B Virus Surface Antigen Prenatal, Serum.
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube: Serum gel (red-top tubes are not acceptable)
Submission Container/Tube: Plastic vial
Specimen Volume: 0.8 mL
Collection Instructions:
1. Centrifuge blood collection tube per manufacturer's instructions (eg, centrifuge and aliquot within 2 hours of collection for BD Vacutainer tubes).
2. Aliquot serum into a plastic vial.
Specimen Minimum Volume
0.7 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum SST | Frozen (preferred) | 90 days | |
| Refrigerated | 6 days | ||
| Ambient | 72 hours |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
Special Instructions
Day(s) Performed
Monday through Saturday
CPT Code Information
87341
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| HBNTP | HBs Ag Confirmation Prenatal, S | 7905-3 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| HBNTP | HBs Ag Confirmation Prenatal, S | 7905-3 |
Clinical Information
Hepatitis B virus (HBV) is a DNA virus that is endemic throughout the world. The infection is spread primarily through percutaneous contact with infected blood products (eg, blood transfusion, sharing of needles among injection drug users). The virus is found in various human body fluids, and it is known to be spread through oral and genital contact. 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 8 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.
For more information see:
-Hepatitis B: Testing Algorithm for Screening, Diagnosis, and Management
-HBV Infection-Monitoring Before and After Liver Transplantation
Interpretation
A reactive screen result (cutoff index values ≥1.00) confirmed as positive by a hepatitis B surface antigen (HBsAg) confirmatory test is indicative of acute or chronic hepatitis B or chronic hepatitis B virus (HBV) carrier state.
Specimens with reactive screen results but negative (ie, not confirmed) HBsAg confirmatory test results are likely to contain cross-reactive antibodies from other infectious or immunologic disorders. If clinically indicated, repeat testing, at a later date, is recommended.
Confirmed presence of HBsAg is frequently associated with HBV replication and infectivity, especially when accompanied by presence of hepatitis B e (HBe) antigen or detectable HBV DNA.
Cautions
This assay has not been licensed by the US Food and Drug Administration  for the screening of blood, plasma, and tissue donors.
For diagnostic purposes, results should always be assessed in conjunction with the patient’s medical history, clinical examination, and other findings.
Individuals, especially neonates and children, who recently received hepatitis B vaccination may have transient positive hepatitis B surface antigen (HBsAg) test results because of the large dose of HBsAg used in the vaccine relative to the individual's body mass.
Positive HBsAg test results will need to be reported by the healthcare provider to their state department of health surveillance units, as required by law in some states.
Current methods for the detection of HBsAg may not detect all infected individuals.
A negative test result does not exclude with certainty a possible exposure to or on infection with the hepatitis B virus (HBV). Negative test results obtained for persons with a past exposure may be caused by an antigen concentration below the detection limit of this assay or the lack of reactivity of the antigens to the antibodies used in this assay.
Performance characteristics of this assay have not been established for testing of newborns or when used in conjunction with other manufacturers’ assays for specific HBV serological markers.
Assay performance characteristics have not been established for the following specimen characteristics or specimen types:
-Grossly icteric (total bilirubin level of >40 mg/dL)
-Grossly lipemic (Intralipid level of >2200 mg/dL)
-Grossly hemolyzed (hemoglobin level of >2200 mg/dL)
-Containing particulate matter
-Cadaveric specimens
-Specimen types other than serum
Method Description
The Elecsys HBsAg (hepatitis B virus surface antigen) II Auto Confirm assay is performed using an electrochemiluminescence immunoassay on the automated cobas e 801 immunochemistry analyzer. This test is based on 2 parallel measurements. Patient's sample is treated first with the control pretreatment reagent (PT2) prior to immunoreaction. This measurement serves as a reference. For the second measurement the sample is treated with the confirmatory pretreatment reagent (PT1) prior to immunoreaction. During incubation with confirmatory pretreatment, unlabeled polyclonal anti-HBs are bound to the sample HBsAg and thereby block the binding sites for the labeled antibodies used in the following immunoreaction. The confirmation result (%) is automatically assessed by determining the ratio of both measurements.
During testing, the auto-diluted sample is incubated with control pretreatment and confirmatory pretreatment, followed by formation of sandwich complexes of biotinylated monoclonal anti-HBs and a mixture of monoclonal anti-HBs and polyclonal anti-HBs labeled with a ruthenium complex. After addition of streptavidin-coated microparticles (solid phase), the complexes bind to the solid phase via interaction of biotin and streptavidin. The reaction mixture is then aspirated into the measuring cell where the microparticles are magnetically captured onto the surface of the electrode. Unbound substances are then washed away, and voltage is applied to the electrode that induces chemiluminescent emissions, which are measured by a photomultiplier. The result is determined by comparing the electrochemiluminescence signal generated from the reaction product in the patient's samples to the cutoff index (COI) value set from reagent lot-specific assay calibration. The confirmation result (%) is calculated from the ratio of the COI obtained for the measurement with confirmatory pretreatment to the COI obtained for the measurement of control pretreatment reaction.(Package insert: Elecsys HBsAg II Auto Confirm. Roche Diagnostics; v1.0, 12/2020)