The Number of Syncytial Knots and VEGF Expression in Placental Villi in Parturient Woman with COVID-19 Depends on the Disease Severity

A comparative morphological study was carried out to analyze the number of syncytial knots and VEGF expression in placental villi in parturient women with COVID-19 categorized by the disease severity. The number of syncytial knots was assessed on specimens stained with hematoxylin and eosin. VEGF expression was determined by immunohistochemical analysis in syncytiotrophoblast and villous endothelial cells. Morphological study of the placenta tissue of parturient women with COVID-19 showed increased numbers of syncytial knots in the villi, indicating the development of preplacental hypoxia. High VEGF expression in syncytiotrophoblast and vascular endotheliocytes reflects a stereotyped response to hypoxia and can underlie the development of a preeclampsia-like syndrome. The number of syncytial knots and VEGF expression in placental villi in parturient women with COVID-19 depended on the disease severity.