Third Trimester Placentas of SARS-CoV-2-Positive Women: Histomorphology, including Viral Immunohistochemistry and in Situ Hybridization.

AIMS: The wide-variety of affected organ-systems associated with SARS-CoV-2 infection highlights the need for tissue-specific evaluation. We compared placentas from SARS-CoV-2-positive and negative women in our hospital in New York City, which became the epicenter of the COVID-19 pandemic in March 2020. While some limited studies have been published on placentas from SARS-CoV-2-positive women to date, this study, in addition to describing histomorphology, utilizes in-situ hybridization (ISH) for the S-gene encoding the spike-protein and immunohistochemistry (IHC) with the monoclonal-SARS-CoV-2 spike-antibody 1A9 for placental evaluation. METHODS AND RESULTS: In this study, 51 singleton, third-trimester placentas from SARS-CoV-2-positive women and 25 singleton, third-trimester placentas from SARS-CoV-2-negative women were examined histomorphologically using the Amsterdam Criteria as well as with ISH and/or IHC. Corresponding clinical findings and neonatal outcomes also were recorded. While no specific histomorphologic changes related to SARS-CoV-2 were noted in the placentas, evidence of maternal/fetal vascular malperfusion was identified, with placentas from SARS-CoV-2-positive women significantly more likely to show villous agglutination (p=0.003) and subchorionic thrombi (p=0.026) than placentas from SARS-CoV-2-negative women. No evidence of direct viral involvement was identified using ISH and IHC. CONCLUSIONS: In this study, third trimester placentas from SARS-CoV-2-positive women were more likely to show evidence of maternal/fetal vascular malperfusion; however, no evidence of direct viral involvement or vertical transmission was noted by ISH and IHC.