Placental Pathology of COVID-19 with and without Fetal and Neonatal Infection: Trophoblast Necrosis and Chronic Histiocytic Intervillositis as Risk Factors for Transplacental Transmission of SARS-CoV-2

• Published in: Viruses Vol. 12; no. 11; p. 1308
• Main Authors: Schwartz, David A, Morotti, Denise
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 15.11.2020; MDPI
• Subjects: Antigens; Chorionic Villi - pathology; Chorionic Villi - virology; chronic histiocytic intervillositis; Chronic infection; Coronaviridae; Coronaviruses; COVID-19; COVID-19 - mortality; COVID-19 - pathology; COVID-19 - transmission; COVID-19 - virology; Female; fetal COVID-19 infection; Fetal Mortality; Fetus; Fetuses; Humans; Hybridization; Immunohistochemistry; Infants; Infectious Disease Transmission, Vertical - statistics & numerical data; maternal COVID-19 infection; Necrosis; Necrosis - mortality; Necrosis - pathology; Necrosis - virology; Neonates; Newborn babies; Placenta; placental COVID-19 infection; Pregnancy; Pregnancy Complications, Infectious - mortality; Pregnancy Complications, Infectious - pathology; Pregnancy Complications, Infectious - virology; Ribonucleic acid; Risk Factors; RNA; RNA, Viral - biosynthesis; SARS-CoV-2 - pathogenicity; Severe acute respiratory syndrome coronavirus 2; Severity of Illness Index; Survival Analysis; trophoblast necrosis; Trophoblasts - pathology; Trophoblasts - virology; Virus Replication; Womens health; Middle East; China; New York City New York; placental COVID-19 infection; maternal-fetal COVID-19; neonatal COVID-19 infection; chronic histiocytic intervillositis; maternal COVID-19 infection; COVID-19; placental risk factors; SARS-CoV-2; vertical transmission; placental pathology; transplacental COVID-19 infection; fetal COVID-19 infection; trophoblast necrosis
• ISSN: 1999-4915; 1999-4915
• DOI: 10.3390/v12111308

The mechanism(s) by which neonates testing positive for coronavirus disease 2019 (COVID-19) acquire their infection has been largely unknown. Transmission of the etiological agent, SARS-CoV-2, from mother to infant has been suspected but has been difficult to confirm. This communication summarizes the spectrum of pathology findings from pregnant women with COVID-19 based upon the infection status of their infants and addresses the potential interpretation of these results in terms of the effects of SARS-CoV-2 on the placenta and the pathophysiology of maternal-fetal infection. Placentas from pregnant women with COVID-19 and uninfected neonates show significant variability in the spectrum of pathology findings. In contrast, placentas from infected maternal-neonatal dyads are characterized by the finding of mononuclear cell inflammation of the intervillous space, termed chronic histiocytic intervillositis, together with syncytiotrophoblast necrosis. These placentas show prominent positivity of syncytiotrophoblast by SARS-CoV-2, fulfilling the published criteria for transplacental viral transmission as confirmed in fetal cells through identification of viral antigens by immunohistochemistry or viral nucleic acid using RNA in situ hybridization. The co-occurrence of chronic histiocytic intervillositis and trophoblast necrosis appears to be a risk factor for placental infection with SARS-CoV-2 as well as for maternal-fetal viral transmission, and suggests a potential mechanism by which the coronavirus can breach the maternal-fetal interface.