Placental pathology related to SARS-COV-2 infection during pregnancy is under investigation, with emerging but still limited and variable data, mainly including changes of fetal and maternal vascular malperfusion. We observed novel pathological findings not previously reported in two term placentas delivered from women mildly affected with COVID-19, with a 2-day and 6-day interval between the onset of symptoms and delivery. The main changes involved the maternal more than the fetal components of the placenta and included a tendency toward thrombosis and fibrin formation, and mild maternal malperfusion. We further observed fibrin degeneration in the intervillous space, the presence of particles of undetermined origin, and mild or moderate maternal decidual inflammatory exudates consisting of monocytes, macrophages, T-lymphocytes, and plasmacytes. Mild inflammation and incipient mural thrombus formation were noted in the fetal vasculature, as well as endothelial vacuolation of the umbilical vessels, not previously described. The maternal changes were more prominent in the case with a relatively longer clinical manifestation-to-delivery interval, and were associated to a prolonged postpartum maternal viral carriage of 30 days and the development of a low-grade febrile response in the neonate. Both infants showed mild morbidity but eventually had a very good outcome. RT-PCR was negative for SARS-CoV-2 RNA in both cases.
We concluded that placental involvement in mild COVID-19 of very short duration at term pregnancy suggested the systemic nature of the disease and appeared related to, though not pathognomonic of COVID-19. Fetoplacental vascular changes and endothelial vacuolation associated with mild neonatal morbidity may suggest a possible transplacental impact on the fetus, to be further investigated.