Significance of hemorrhagic endovasculitis in placentae from stillbirths

Hemorrhagic endovasculitis (HEV) is an alteration of fetal chorionic blood vessels within the placenta. This disruption of the integrity of the parietal blood vessels has been reported in association with poor pregnancy outcomes and perinatal complications. In stillbirths, its presence has been implicated as part of the mechanism of the cessation of fetal circulation in postmortem retention of the placenta. The purpose of this study was to give an interpretation of this type of blood vessel damage: whether it is related to the arrest of blood circulation after stillbirth, or whether it constitutes an alteration of the integrity of placental chorionic circulation contributing to the death of the fetus. From 1232 reviewed placentae, we analyzed 46 cases with HEV, 70% from livebirths and 30% from stillbirths. The most frequent lesions encountered in placentae were categorized microscopically. The distribution of these lesions in placentae from livebirth and stillbirth pregnancies was then described. In association with HEV, villitis of unknown etiology and chorionic vessel thrombi occurred more frequently in placentae from livebirths. Fragmented erythrocytes and erythroblasts were more frequent in placentae from stillbirths. Our study demonstrates that HEV is more consistently associated with other placental lesions in liveborn than in stillborn infants.