Histopathological and clinical analysis of COVID-19-infected placentas

Background The impact of COVID-19 pandemic in pregnant patients is an important emerging topic. Evidence of transplacental transmission and typical histopathological alterations in the placenta are controversial in the literature. Methods This was a prospective observational cohort multicenter study in which we selected 23 placentas of 21 patients that showed detection of SARS-CoV-2 RNA by RT-PCR in the placenta tissue and described both morphological and clinical characteristics. Immunohistochemistry was performed to localize the virus in the specimens. Results Most of the patients were asymptomatic (61.9%) and preterm delivery was observed in 8 patients (34.7%). In relation to histopathological features, all the placentas showed evidence of maternal vascular malperfusion, as well as some degree of villitis with a high frequency of high grade placentitis (73.9%) and chronic and/or acute intervillositis (82.6%). We observed immunopositivity for SARS-CoV-2 antibody in 69.5% of the cases, notably in the syncytiotrophoblast. Conclusions We reported histopathological features of placentas with viral detection in the tissue, thus providing evidence that SARS-CoV-2 can affect the placenta, although maternal and neonatal clinical outcome is usually mild.