A case of a false positive HIV antigen/antibody screen in a pregnant woman at delivery and the clinical importance of reviewing signal-to-cutoff ratio values

We present a unique case not previously touched upon in the literature, and its ensuing management, of a falsely reactive HIV (human immunodeficiency virus) screening test which resulted in a woman during active labor, hours after rupture of membranes. The patient was screened for HIV using the ARCHITECT 4th generation HIV 1 and 2 Antigen/Antibody (Ag/Ab) Combo assay, and the results were repeatedly reactive. A cesarean delivery was recommended, and the patient received intrapartum antiretroviral therapy. Due to rapid progression of labor, the infant was delivered vaginally and received multiple doses of antiretroviral therapy. For confirmation, a viral load PCR test was obtained which resulted undetectable, and it was concluded that the screening results were falsely positive. While the cause of the inaccurate screening result is still unclear, a COVID-19 vaccination in close proximity to the delivery remains suspicious. Four months after delivery, the patient’s screening test was no longer reactive.