What is the recommended initial HIV screening test for an at-risk pregnant individual?

Initial HIV Screening Test for At-Risk Pregnant Individuals

The recommended initial HIV screening test for at-risk pregnant individuals is a fourth-generation HIV antigen/antibody combination assay, which should be performed as early as possible during pregnancy as part of routine prenatal care. 1, 2

Testing Protocol and Algorithm

Standard Testing Protocol

• The HIV testing algorithm consists of:
  1. Initial screening with an FDA-licensed enzyme immunoassay (EIA)/fourth-generation combination test
  2. Confirmatory testing of repeatedly reactive EIAs with an FDA-licensed supplemental test (e.g., Western blot) 1

Fourth-Generation Testing Benefits

• Fourth-generation assays simultaneously detect HIV p24 antigen and antibodies, reducing the diagnostic window period to approximately 11-14 days after infection 2, 3
• These tests can detect HIV infection earlier than antibody-only tests, allowing for more timely interventions 2, 4
• Studies have shown fourth-generation assays have high sensitivity and specificity (99.91-99.97%) 5

Timing and Frequency of Testing

• Testing should be performed as early as possible during pregnancy to allow for timely therapeutic decisions 1
• Retesting in the third trimester (preferably before 36 weeks) is recommended for:
  • Women at high risk for HIV (history of STDs, multiple sex partners, injection drug use, sex partners who are HIV-positive) 1
  • All women in jurisdictions with elevated HIV/AIDS incidence
  • Women receiving care in facilities with at least one diagnosed HIV case per 1,000 pregnant women per year 1

Special Testing Considerations

For Women in Labor with Unknown HIV Status

• Rapid HIV testing should be performed immediately 1
• Expedited testing options include:
  1. Rapid return of results from standard testing
  2. Use of rapid testing with confirmation by a second licensed test when available 1
• Immediate antiretroviral prophylaxis should be initiated based on a reactive rapid test result, without waiting for confirmatory testing 1

Postpartum/Newborn Testing

• When a woman's HIV status remains unknown at delivery, she should be screened immediately postpartum with a rapid HIV test 1
• If maternal status remains unknown, rapid testing of the newborn is recommended as soon as possible after birth 1
• Neonatal antiretroviral prophylaxis is most effective when initiated within 12 hours of birth 1

Consent and Education

• HIV screening should be included in the routine panel of prenatal screening tests
• Patients should be informed that HIV testing is recommended and will be performed unless they decline (opt-out screening) 1
• Before testing, healthcare providers should provide basic information about:
  • HIV transmission routes
  • Risk of perinatal transmission (approximately 25% without treatment)
  • Benefits of early detection and treatment
  • Available interventions to prevent transmission 1

Pitfalls and Caveats

• False-positive results can occur, though rare when both screening and confirmatory tests are reactive 1
• Indeterminate Western blot results occur more frequently in pregnant women than other populations 1
• Rapid tests have lower positive predictive value in low-prevalence populations and require confirmatory testing 1
• Fifth-generation assays that provide separate antigen and antibody results are becoming available but may require different testing algorithms 3

By implementing this testing approach, healthcare providers can identify HIV infection early in pregnancy, allowing for timely interventions that significantly reduce perinatal transmission risk and improve health outcomes for both mother and child.