Stillbirth and fetal capillary infection by SARS-CoV-2

We present the case of a stillbirth in a paucisymptomatic mother affected by SARS-CoV-2. At gross examination, the placenta showed a diffuse marbled appearance and a focal hemorrhagic area. Multiple areas of hemorrhagic/ischemic necrosis with central and peripheral villous infarctions and thrombosis of several maternal and fetal vessels with luminal fibrin and platelet deposition was observed. All the lesions appeared to be synchronous. Virus particles were identified by Electron Microscopy within the cytoplasm of endothelial cells whereas, by real time rRT-PCR assay, SARS-CoV-2 RNA was detected in placental tissue. In this case, fetal vascular malperfusion was likely casually associated with the infection; indeed, our EM images clearly showed that the marked SARS-CoV-2 endotheliotropism involved the intravillous fetal capillaries. We confirmed that syncytiotrophoblast is the major target cell type for SARS-CoV-2 infection of the placenta. In conclusion, the possible consequences of the action of the placentotropic SARS-CoV-2 include the occurrence of vertical transmission, as reported in literature, and/or stillbirth: this latter possibility may be triggered by a hampered maternal and/or fetal perfusion of the placenta. The diffuse thrombosis and subsequent ischemia of fetal capillaries induced by COVID-19 cannot be predicted by standard clinical surveillance.