Variability in pathologists' detection of placental meconium uptake

Placental meconium has been associated with poor perinatal outcomes but the reliability of the diagnosis has not been assessed. Our objective was to assess the interobserver variability in detection of placental meconium uptake. Ten pathologists from two community and four university hospitals reviewed 10 hematoxylin and eosin-stained placental slides that included cases of in utero and in vitro meconium uptake as well as negative controls. Pathologists rated amnion denudation, presence, location, and density of meconium. Results were compared using a kappa score measure of concordance. There was fair concordance in samples with > 50% amnion denudation (kappa = 0.42), though overall amnion integrity concordance was poor (kappa = 0.18). Similarly, poor concordance was noted for presence (kappa = 0.13), location (kappa = 0.06), and density of meconium staining (kappa = 0.11). Detection of meconium uptake in placentas is highly variable among a representative group of community and university pathologists. This finding suggests a need for a more objective measure of meconium uptake in placentas.