Acute and chronic placental membrane hypoxic lesions.

Laminar necrosis (LN) and microscopic chorionic pseudocysts (MCP) are the two histological placental membrane lesions. This study retrospectively compares the clinical and placental associations of LN and MCP on a large placental material. Four hundred seventy-nine placentae featuring membrane LN (group 1), 220 placentae with MCP (group 2), and 50 placentae with both LN and MCP were identified in the database of consecutively signed by the author 4,853 placentae from 18 to 42 weeks pregnancies in years 1994-2007. Frequencies or averages of several clinical conditions and gross and microscopic placental features were compared among the groups (Yates chi-square or analysis of variance, where appropriate). Statistically significant differences were observed for preeclampsia, diabetes mellitus, stillbirths, cesarean section deliveries, placental weight, gross chorionic cysts, maternal chorioamnionitis, fetal chorioamnionitis, marginate placentae, and excessive amount of extravillous trophoblasts, respectively. Based on the above results, LN, a membrane infarction, appears to be an acute membrane hypoxic lesion, while MCP is a chronic lesion related to a more widespread extravillous trophoblasts accumulation in the placental disk. There was a substantial overlap of other clinical and placental conditions among the groups, paralleling not uncommon coexistence of acute and chronic placental hypoxia, therefore, LN and MCP, in same placentae.