Gross appearance of the fetal membrane on the placental surface is associated with histological chorioamnionitis and neonatal respiratory disorders.

An opaque fetal membrane based on gross appearance is traditionally indicative of histological chorioamnionitis; however, to the best of our knowledge, there is currently no supportive evidence, and its diagnostic efficiency has not yet been scientifically demonstrated. The present study aimed to provide scientific insights into the traditional concept of an opaque fetal membrane based on gross appearance being an indicator of histological chorioamnionitis. We examined the placental pathology after screening of the placental gross appearance and perinatal complications and did not examine uncomplicated deliveries. We investigated the relationship between the presence of an opaque fetal membrane and histological chorioamnionitis (Cohort 1, 571 placentas) or the outcomes of neonates delivered at term (Cohort 2, 409 placentas) at Hamamatsu University School of Medicine between 2010 and 2017. The judgment of a positive opaque fetal membrane based on gross appearance correlated with histological chorioamnionitis (Cohort 1). Its sensitivity and specificity were 66.7 and 89.9%, respectively, while positive and negative predictive values were 86.8 and 73.0%, respectively. The judgment of a positive opaque fetal membrane based on gross appearance significantly correlated with chorioamnionitis-related complications in term newborns after adjustments for confounding factors (OR;1.82 [1.07-3.11], P<0.05) (Cohort 2). A correlation was observed even after adjustments for confounding factors. The present study is the first to demonstrate that the judgment of a positive opaque fetal membrane based on gross appearance correlated with histological chorioamnionitis as well as chorioamnionitis-related complications in newborns delivered at term. The present results provide support for the traditionally-described importance of gross inspections for an opaque fetal membrane soon after birth.