Placental histopathology and SARS-COV-2 infection: Preliminary findings

INTRODUCTION The receptors of SARS-CoV-2 are present in several extrapulmonary sites, such as on the placenta. It could potentially contribute to vertical transplacental transmission to the fetus. Despite the placentas were tested positive for SARS-CoV-2, there are few newborns which showed virus-induced diseases. To data, there are no pathognomonic histological patterns in human placentas following SARS-CoV- 2 maternal infection. METHODS We reviewed the data on placentas of all pregnant women in third trimester with confirmed SARS-CoV-2 infection, who delivered to San Marco Hospital, COVID-19 Department of Gynecology and Obstetrics, from March 2020 to March 2021. The placentas were sent to histological examination and COVID-19 Time Quantitative Reverse Transcription PCR (qRT-PCR) swabs, both in maternal and fetal faces. RESULTS Pregnant women who underwent to a caesarean section was higher (68%) than those who delivered vaginally (32%). The isthological study of the 110 placentas showed 32% of cases with histological normal placentas (no infarctions or chorionic amniotic inflammation) and 67% with a dense macrophage infiltrate with acute chorioamnionitis but no viral cytopathic changes. Only 1% of placentas had an evidence of calcifications, fibrin deposition inside and around the villi, and 'syncytial nodules,' more commonly described as syncytial nuclear aggregates (SNAs). No definite thrombosis was found in these cases. Only two cases of placentas were reported positive for the presence of SARS-CoV-2. Both newborns were tested for SARS-CoV-S through nasal and rectal swab, performed at 1 h, 72 h, 14 days and 28 days from the birth. All samples tested negative for the virus. One male newborn, after vaginal delivery at 39° weeks of gestation, weighed 2750 g and Apgar score was 8 and 9 at 1 and 5min. The placenta was histologically and morphologically normal. Another male newborn, vaginally delivered at 39 weeks, had an Apgar score of 9 and 10 at 1 and 5 min after birth and he weighed 3170 g. The placenta examination revealed calcifications, fibrin deposition inside and around the villi and SNAs. No abnormalities of the placenta and umbilical cord were described. Both newborns showed good conditions and they were asymptomatic during the hospital stay in roomingin regimen. CONCLUSIONS Due to the role of the placenta on fetus development, a research incorporating placental tissue collection and an assessment should be done to better understand the pathogenic mechanism of COVID-19 on pregnancy outcome.