VP31.17: Prevalence of SARS‐CoV‐2 in asymptomatic patients

Abstract

Objectives:The aim of this study was to describe the placental lesions associated to SARS-CoV-2 infection by means of synchrotron X-ray phase-contrast imaging (X-PCI). Methods: Two blocks of placental tissue containing each a full thickness of placental parenchyma fixed by 10% buffered formalin were obtained from a laboratory confirmed SARS-CoV-2 positive placenta from a case of severe maternal COVID-19 and stillbirth at 37 weeks of gestation, and a second from a SARS-CoV-2 negative normal pregnancy. The two samples were introduced in a tube with deionised degassed water (figure A) and imaged in 3D with X-PCI at TOMCAT beamline (SLS, Switzerland) at an energy of 20 keV using a multiscale propagation-based protocol. First the whole sample was imaged at low-resolution (5.8 um pixel size). Then an area covering the full thickness from maternal to fetal side was selected for each sample (figure A) and imaged at high-resolution (HR) (0.65 um pixel size). Results: SARS-Cov-2 positive placenta shows lesions characterised by intervillous space collapse (figure C) and perivillous fibrinoid deposition (figure D) as compared to control placenta (figure B). Conclusions: Synchrotron X-PCI seems to be a powerful technique for multiresolution structural investigation of the placenta ex-vivo that could provide further insights in the SARS-CoV-2 infection in pregnancy.