Coronavirus disease 2019 (Covid-19) during pregnancy Pathomorphological changes in the terminal villi of the placenta

Abstract

ABSTRACT Aim: To investigate the pathomorphological changes in the terminal chorionic villi during COVID-19 in pregnant women. Materials and Methods: A total of 123 placentas were studied in cases of live term births (groups І) and antenatal asphyxia (groups ІІ). The subgroups were defined as follows: II.2 and I.2 (post-COVID interval of 1–4 weeks); I.1 and II.1 (5–16 weeks). Morphological and statistical research methods were applied. Results: Spherical structures resembling viral particles were identified in the placenta. In 100 % of the observations, damage to the microcirculatory bed of terminal villi was detected, manifested by cytoplasmic edema of endothelial cells, disruption of cell membranes, nuclear apoptosis and placentitis. With increasing duration of the post-COVID interval, a gradual restoration of endothelial functional activity was observed, evidenced by an increase in laminar microvilli and vesicles, as well as widening of the vascular lumen; whereas in cases of antenatal asphyxia, obliteration of the vascular lumen and stromal fibrosis were noted. A reduction in endothelial cell cytoplasmic edema and stromal edema of terminal chorionic villi was also observed. Conclusions: The morphogenesis of placental dysfunction in cases of antenatal fetal asphyxia associated with immature protective mechanisms involves endothelial dysfunction, impaired microcirculation, inflammatory infiltration, stromal edema of terminal villi with a reduction in vascular lumen, and subsequent fibrosis. The detection of viral particles with increasing post-COVID interval suggests persistence of SARS-CoV-2, the long-term effects of which on vascular function and its role in the development of placental insufficiency require further investigation.