Navigating false positive HIV test results: a case report

All Food and Drug Administration-approved laboratory-based human immunodeficiency virus (HIV) screening tests have high sensitivity and specificity. There is an HIV diagnostic test algorithm recommended by the Centers for Disease Control and Prevention (CDC) and Association of Public Health Laboratories (APHL) in the United States. Still, diagnostic challenges can occur in real-world practice. We describe an unusual case that exhibited false positive results for HIV screening and confirmation testing.

A 27-year-old cisgender female had HIV testing as part of antenatal care. Her local HIV-1/2 antigen/antibody (Ag/Ab) screening test was reactive, and the HIV Ab differentiation assay was positive for HIV-1. Using CDC and APHL algorithm guidelines, she was diagnosed with HIV-1 infection. However, her HIV-1 ribonucleic acid (RNA) quantitative polymerase chain reaction was undetected. Although she immigrated from an HIV-1 high prevalence region, she was otherwise at low risk for HIV transmission. Qualitative HIV-1 deoxyribonucleic acid/RNA was undetected, and HIV-1 Western blot analysis was only positive for HIV-1 gp160 reactivity, confirming that her initial testing represented a false positive and that she did not have HIV infection. The rest of her pregnancy and delivery course was uneventful.

Our case highlights the limitations of current HIV diagnostic tests and challenges in interpretation. Clinicians should be aware that false-positive tests are rare and be reminded to consider the pre-test probability when interpreting results.