EXPRESS: SARS-CoV-2 immunochromatographic IgM/IgG rapid test in pregnancy: a false friend?

Background An increasing body of evidence has revealed that SARS-CoV-2 infection in pregnant women could increase the risk of adverse maternal and fetal outcomes. Careful monitoring of pregnancies with COVID-19 and measures to prevent neonatal infection are warranted. Therefore, rapid antibody tests have been suggested as an efficient screening tool during pregnancy. Cases We analysed the clinical performance during pregnancy of a rapid, lateral-flow immunochromatographic assay (ICA) for qualitative detection of SARS-CoV-2 IgG/IgM antibodies. We performed a universal screening including 169 patients during their last trimester of pregnancy. We present a series of fourteen patients with positive SARS-CoV-2 ICA rapid test result. ICA results were always confirmed by chemiluminescent microparticle immunoassays (CMIA) for quantitative detection of SARS-CoV-2 IgG and IgM+IgA antibodies as the gold standard. We observed a positive predictive value (PPV) of 50% and a false positive rate (FPR) of 50% in pregnant women, involving a significantly lower diagnostic performance than reported in non-pregnant patients. Discussion Our data suggest that although ICA rapid tests may be a fast and profitable screening tool for SARS-CoV-2 infection, they may have a high false positive rate and low positive predictive value in pregnant women. Therefore, Immunochromatographic assay for qualitative detection of SARS-CoV-2 IgG/IgM antibodies must be verified by other test in pregnant patients.