key: cord-0699864-axwwu51w authors: Gioia, Cira di; Zullo, Fabrizio; Vecchio, Roberta Costanza Bruno; Pajno, Cristina; Perrone, Giuseppina; Galoppi, Paola; Pecorini, Francesco; Mascio, Daniele Di; Carletti, Raffaella; Prezioso, Carla; Pietropaolo, Valeria; Masuelli, Laura; Bei, Roberto; Ciallella, Costantino; Rocca, Carlo Della; Giancotti, Antonella; Brunelli, Roberto title: Stillbirth and fetal capillary infection by SARS-CoV-2 date: 2021-10-24 journal: Am J Obstet Gynecol MFM DOI: 10.1016/j.ajogmf.2021.100523 sha: 7879cbdd86ceef4835a4fc49cd79cc0e54683881 doc_id: 699864 cord_uid: axwwu51w 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. 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. In the setting of seasonal influenza epidemics, pregnancy is associated with higher risk of severe complications, as a result of the physiological adaptation of immune, cardiovascular and respiratory systems. 1 Although there is little information published regarding the impact of COVID-19 on pregnancy outcomes, an increased rate of pregnancy loss, stillbirth, and preterm delivery has been reported. 1 In particular, the 2020 report of the United Nations Inter-agency Group for Child Mortality Estimation (UN IGME) underlined the possible association between the lack of adequate and quality obstetric care and the increased incidence of stillbirth during the outbreak. 2 The rate of positive COVID-19 tests in infants born to mother affected by SARS-CoV-2 is very low with a pooled proportion of vertical transmission of 3.2% 3 and the exact mechanism of vertical transmission and placental damage is still to be defined. A 33-years-old Caucasian woman, gravida 3 para 2 was referred to our Obstetric Emergency Room, Policlinico Umberto I, Sapienza University of Rome, at 36 weeks + 1 day of gestation, with preterm labor and a positive nasopharyngeal swab (NFS) for SARS-CoV-2, thus leading to a diagnosis of asymptomatic COVID-19 infection. Vital parameters at admission were normal. Ultrasonographic assessment showed absent fetal movement and absent heartbeat. Shortly after arrival, a dead male fetus was delivered vaginally, with meconium-stained amniotic fluid. Patient's past medical history was unremarkable. Previous pregnancy routine exams including ultrasonographic assessments and Non-Invasive Prenatal Test (NIPT) showed no abnormalities. At 34 weeks the patient developed fever that lasted 5 days, with a daily average body temperature of 39°C. The autoptic findings showed that neonatal death occurred in a time ranging between 24 hours and 5 days before delivery. Swabs obtained from fetal right and left main bronchus, small intestine and rectum resulted negative for SARS-CoV-2 RNA by RT-PCR assay. The maternal and fetal surfaces showed no macroscopic alterations with normal amniochorionic membranes. Sectioning and examination showed a diffuse marbled appearance and a focal hemorrhagic area (1.5 cm of diameter) near the basal plate ( Fig.1.1) . Umbilical cord showed normal diameter, three umbilical vessels and hypercoiling with normal umbilical coiling index. At light microscope, the placental tissue showed multiple areas of hemorrhagic/ischemic necrosis with central and peripheral villous infarctions. (Fig. 2.1 ) Thrombosis of several fetal and maternal vessels with luminal fibrin and platelet deposition was observed with some suggestive figures of intramural fibrin deposition in a vessel of the chorionic plate ( Fig. 2.2-3 ). All the lesions appeared to be synchronous. There was no histologic sign of chorioamnionitis or umbilical arteritis. The villi showed SARS-CoV spike immunohistochemical positivity of syncytiotrophoblasts and endothelial cells (Fig. 3.1-2) . Ultrastructural analysis of placental tissue showed a partially preserved structure due to post-mortem alterations and delayed tissue fixation with different extent of cellular swelling. Virus particles were identified mainly within the cytoplasm of endothelial cells, in the cytosol and in cytoplasmic vacuoles, or adjacent to damaged endothelial cells (Fig. 4.1-3 ). Budding of viral particle was also observed. The The risk of vertical transmission in SARS-CoV-2 infection represents an obvious issue of concern, although occurring rarely, with an overall proportion of approximately 3% 4 . On the other hand, the risk of stillbirth among pregnant women with a confirmed peri-partum SARS-CoV-2 infection is significantly increased 5 . In a previous series 6 of 5 stillborn infants, all placentas were characterized by the presence of chronic histiocytic intervillositis, syncytiotrophoblast necrosis and massive fibrin deposition leading to a condition of intervillous malperfusion that likely determined the fetal demise. While confirming the presence of decidual inflammation and perivillous fibrin deposition, another report highlighted the contribution of fetal vascular malperfusion as a hallmark of placental histopathological alterations attributable to SARS-CoV-2. 7 In the present study, we report a case of a stillbirth occurring in the absence of vertical transmission. inflammation neither to massive syncytiotrophoblast necrosis; rather, diffuse thrombosis of fetal intravillous vessels appeared as the hallmark of placenta infection. In this case, fetal vascular malperfusion was likely associated casually, rather than being simply coincident with the infection; indeed, our electron microscopy (EM) images clearly showed that the marked SARS-CoV-2 endotheliotropism involved the tiny intravillous fetal capillaries leading to cell dysfunction and procoagulant activity. Of note, scoring SARS-CoV-2 in the endothelium of villous capillaries indicates that the virus transfer towards the fetal circulation follows a classical transendothelial route and does not involve the Trojan horse mechanism of maternal/fetal cell transfer described for other placentotropic agents 8 . We confirmed that syncytiotrophoblast is the major target cell type for SARS-CoV-2 infection of the placenta, possibly due to the highly expressed levels ACE2. Since syncytiotrophoblast may be crossed by COVID-19 even in presence of subtle defects, the epidemiological evidence of a low vertical transmission rate envisages the role of additional local factors, including the still uncertain modulation of Hofbauer cells in either preventing or permitting virus transmission and replication 9 . Since placental infection does not always correlate with infection of the fetus, it is plausible that a time interval may ensue between these two processes; a stillbirth that occurs in this time frame can be mechanistically explained by an overriding process of severe endothelial dysfunction occurring within intravillous capillaries or massive hypoperfusion of the intervillous space. However, we cannot disregard that a negative evidence of COVID-19 transmission in the setting of an intrauterine fetal demise must be interpreted with caution because of the sensitivity of testing for SARS-CoV-2 in neonatal autopsy specimens 10 . In conclusion, the possible consequences of the action of the placentotropic SARS-CoV-2 include the occurrence of vertical transmission and/or stillbirth as in our case: this latter possibility may be Outcome of coronavirus spectrum infections (SARS, MERS, COVID-19) during pregnancy: a systematic review and meta-analysis United Nations Inter-agency Group for Child Mortality Estimation (UN IGME) 2020 Vertical transmission of coronavirus disease 2019: a systematic review and meta-analysis Maternal and perinatal outcomes of pregnant women with SARS-CoV-2 infection at the time of birth in England: national cohort study Fetal deaths in pregnancies with SARS-CoV-2 infection in Brazil: A case series. Case Rep Womens Health SARS-CoV-2 and Placenta: New Insights and Perspectives SARS-CoV2 vertical transmission with adverse