The placenta in meconium staining: lesions and early neonatal outcome

To evaluate the immediate neonatal outcome and the presence of various placental lesions in 96 pregnancies with meconium-stained amniotic fluid.

The patients were divided into a group with acute (N = 41) and subacute and chronic (N = 55) meconium staining of the placenta. Apgar scores, arterial cord pH and admission to the neonatal intensive care unit (NICU) were determined in addition to the findings on gross and microscopic examination of the placentas.

Of the 53 live births with subacute and chronic meconium staining, 13% had Apgar Scores < or = 7 at 5 minutes compared to 7% with acute meconium staining. Similarly, a significantly lower umbilical artery pH was determined in the former group [(32%) versus (7%)], (p < 0.01). When 9 different pathologic lesions of the placenta were evaluated microscopically, the frequency of villous vascular thrombosis (25.4%), infarcts (38%), acute chorioamnionitis (20%), villous edema (9.1%) and villitis (14.5%) was significantly higher in the group with longer meconium exposure compared to the other group (2.4%), (9.7%), (7.3%), (0%), and 1 (2.4%), respectively. In addition, when tested for 4 different lesions, cases with acute meconium were less likely to have one or more lesions. When one or more placental lesions were found, NICU admission rate was significantly higher in the patients with subacute and chronic meconium.

Subacute and chronic meconium discharge is associated with significant placental lesions and an increased risk of adverse pregnancy outcome in the immediate neonatal period.