Implication of Meconium-aspirated Lungs in Stillborns and Neonatal Deaths

Intrauterine passage of meconium into amniotic fluid is thought to occur in response to fetal distress, in which meconium aspiration syndrome is a serious complication in delivery. This retrospective study describes postmortem histological examination to detect amniotic elements in the lungs of stillborns and neonatal deaths. Alcian blue stain and immunohistochemistry using antibodies to sialyl Tn and cytokeratin were performed for formalin-fixed tissues obtained from nine subjects: four stillborns and five neonates. Meconium masses occluded the bronchiolar and alveolar spaces in the lungs of five infants to varying extents. One case of clinically diagnosed meconium aspiration syndrome and another of an abandoned neonate exhibited a high degree of meconium occlusion. In the latter case, fetal distress was presumed to have occurred, as inferred from the histopathological features. The other three stillborns demonstrated a mild degree of small meconium, distributed mainly to alveolar spaces, in which it remained unknown whether this amount of meconium affected stillbirth. As another perspective, amniotic squames were evaluated by immunohistochemistry. Even fewer squames were present in alveoli of the lungs of all live-born subjects, indicating that complete exhalation or degeneration of amniotic elements occurs after several days following birth. Forensic autopsy cases of deceased infants often lack clinical management and detailed information. Meconium contamination in the lung sections is a finding that can indicate antepartum or intrapartum compromised status of infants.