The US Public Health Service recommends that HIV-1 testing and counseling be offered to all pregnant women regardless of risk factors and the prevalence rates in the community (19,47). Offering of HIV-1 testing in the hospital, clinic, or private office should be universal and a routine part of prenatal care. Laws regarding HIV-1 testing are not uniform from state to state, and health care providers should be familiar with and follow local and state laws, regulations, and policies regarding HIV-1 screening of pregnant women and their infants (48). In some states, the offering of HIV-1 testing is mandated, and in others, such as New York, there is mandatory HIV-1 testing of all newborns.
In most states, pregnant women receive pre-HIV-1 test counseling and must specifically consent to an HIV-1 antibody test, usually in writing. Pretest counseling should include information about HIV-1 and the risks and benefits of HIV-1 testing presented orally or in writing (such as a pamphlet) and in a language the client understands.
Other states have adopted an Opt-out approach by which pregnant women are notified that an HIV-1 test will be routinely included in the standard battery of prenatal tests for all pregnant women, but they can decline HIV-1 testing (47). This approach allows women to decline testing if they feel it is not in their best interest and simplifies the testing process by eliminating the need for extensive pretest counseling. Accepting or refusing testing must not have detrimental consequences to the quality of prenatal care offered. The woman should be made aware that test results are confidential, but positive results are reported to the state health department in those states that have HIV-1 reporting laws. Under no circumstance are test results disclosed over the phone, through mail, or by facsimile. The mother should be given a date to return for posttest counseling once results are available. Counseling should be done for both positive and negative results. If a woman has a positive HIV-1 enzyme-linked immunosorbent assay (ELISA) with confirmatory Western blot, then she should receive the appropriate posttest counseling and be referred to an obstetrician who has experience in the care of the HIV-1-infected pregnant woman. If an obstetrician is not available, then an internist with knowledge of HIV-1 treatment should be consulted. If the woman tests negative for HIV-1, she should be counseled on how HIV-1 is transmitted and how to avoid contracting HIV-1 infection.
The standard test for diagnosis of HIV-1 in adults is the HIV-1 ELISA combined with a confirmatory test, either the HIV-1 Western blot or immunofluorescent assay (IFA). Of these two confirmatory tests, the Western blot is more commonly used. The HIV-1 ELISA test detects immunoglobulin G antibodies to HIV-1 in the blood. If an HIV-1 ELISA test is positive, the test is repeated using the same blood sample; if it is repeatedly reactive, then a Western blot test is done to determine which viral proteins the antibodies are directed against. Although the result of the HIV-1 ELISA is usually available within 24 hours, the Western blot will take longer to complete.
Both the ELISA and the Western blot must be positive to confirm HIV-1 infection (49). In some cases, an ELISA may be positive, but the Western blot is negative, resulting in a false-positive ELISA. This person is not considered to be HIV-1 infected. If the ELISA is positive and the Western blot is indeterminate, then this may represent either early HIV-1 infection or a person without HIV-1 infection. In this case, the test needs to be repeated; in addition, an HIV-1 DNA PCR assay should be done. This test detects the presence of virus directly and, if positive, would diagnose HIV-1 infection. It is important to have both results before counseling a woman regarding her HIV-1 status. HIV-1 testing should be offered to the pregnant woman early in pregnancy so appropriate therapy can be initiated if the woman is HIV-1 infected. Retesting in the third trimester, preferably before 36 weeks of gestation, is recommended (50,51).
For the woman who does not receive prenatal care or comes to labor and delivery without knowledge of her HIV-1 status, rapid HIV-1 testing can be offered (52,53).
There are four rapid HIV-1 tests approved by the Food and Drug Administration for use in the United States: the OraQuick Rapid HIV-1 Antibody test, the Reveal Rapid HIV-1 Antibody Test, the Uni-Gold Recombigen HIV-1 Test, and the Murex-SUDS-Single Use Diagnostic System HIV-1 Antibody Test (manufacture of this test was discontinued in 2003). All have good sensitivity and specificity. As with other HIV-1 testing, consent is required for the rapid test, and if positive, a follow-up HIV-1 ELISA and Western blot or IFA test needs to be done to confirm the HIV-1 infection. The advantages of this test are that results are available within 30-60 minutes, and the results can be immediately given to the individual tested. A reactive result from a rapid test is considered to be a preliminary positive test result. Thus, if a pregnant woman does not know her HIV-1 status and is late in gestation, a positive rapid HIV-1 test can be used to institute antiretroviral therapy, or if she is in labor, she should be counseled and have the option to receive intravenous ZDV during labor and give ZDV to the newborn within the first 12 hours of life (54). Observational studies and clinical trials have shown that when antiretroviral prophylaxis is administered during labor or within the first 12 hours after birth, the risk of perinatal HIV-1 transmission is reduced from 25 to 9-13% (55,56).
The majority of HIV-1 infection in the United States is caused by HIV-1 subtype B. Standard HIV-1 ELISA screening tests may be negative in 20-30% of patients infected with HIV-2. HIV-2 infection is predominately found in western sub-Saharan Africa. Detection in these cases may require specific testing for HIV-2. These screening tests may also fail to detect the O subtype, which is very rare in the United States. Another rare subtype, N, is not detected with the HIV-1 ELISA but may be positive by Western blot tests (57).
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