What is the recommended initial HIV screening test for a pregnant patient at risk?

Initial HIV Screening Test for Pregnant Patients at Risk

The recommended initial HIV screening test for pregnant patients at risk 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

Testing Algorithm and Approach

The complete HIV testing algorithm consists of:

1. Initial screening: FDA-licensed fourth-generation combination test that detects both HIV antibodies and p24 antigen
2. Confirmatory testing: For repeatedly reactive results, an FDA-licensed supplemental test (e.g., Western blot) should be performed 1

Fourth-generation assays offer significant advantages over earlier generation tests:

• They simultaneously detect HIV antibodies and p24 antigen
• They can reduce the diagnostic window by up to 2 weeks compared to antibody-only tests 2
• They demonstrate similar sensitivity across diverse HIV subtypes 3

Timing of Testing

• Testing should be performed as early as possible in pregnancy to allow for timely interventions
• Retesting in the third trimester (preferably before 36 weeks) is recommended for:
  • Women at high risk for HIV
  • Women in areas with elevated HIV/AIDS incidence
  • Women receiving care in facilities with ≥1 diagnosed HIV case per 1,000 pregnant women per year 1

Special Circumstances: Labor and Delivery

For women presenting in labor with unknown or undocumented HIV status:

• Expedited testing should be performed immediately using either:
  • Rapid return of results from standard testing, or
  • Rapid HIV testing with confirmation by a second licensed test 4, 1
• Antiretroviral prophylaxis should be initiated based on a reactive rapid test result, without waiting for confirmatory testing 1
• The goal is to identify HIV-infected women as soon as possible, as prophylactic therapy is most effective when given during or within 12 hours after exposure 4

Important Considerations

• Informed consent: HIV testing should be voluntary with appropriate informed consent, though an opt-out approach is recommended 4, 1
• Patient education: Providers should explain HIV transmission routes, risk of perinatal transmission, benefits of early detection, and available interventions 1
• Test limitations:
  • False-positive results can occur, though rarely when both screening and confirmatory tests are reactive
  • Indeterminate Western blot results occur more frequently in pregnant women 1
  • Rapid tests have lower positive predictive value in low-prevalence populations 4

Postpartum and Neonatal Testing

If maternal HIV status remains unknown at delivery:

• The mother should be screened immediately postpartum with a rapid HIV test
• If maternal status still remains unknown, rapid testing of the newborn is recommended as soon as possible after birth
• Neonatal antiretroviral prophylaxis is most effective when initiated within 12 hours of birth 1

By implementing this comprehensive testing approach, healthcare providers can significantly reduce the risk of perinatal HIV transmission and improve maternal and infant outcomes.