Placenta membranacea.

Placenta membranacea is a rare placental disorder characterized by the presence of fetal membranes (complete or partially) covered by chorionic villi. A 35-year-old woman, gravida 1, was admitted for preterm labor at 24 weeks and 5 days. She subsequently developed heavy vaginal bleeding and underwent a classical cesarean delivery for suspected abruption. Postpartum inspection of the placenta demonstrated a small placenta with tan colored membranes, and diffusely scattered placental cotyledons. Histologic examination revealed chorionic villi directly attached to the fetal membranes on the periphery,consistent with the diagnosis of a partial placenta membranacea. Placenta membranacea should be considered in the etiology of painless vaginal bleeding in the second and third trimester. This condition can be associated with other placental abnormalities, such as placenta previa or accreta. Perinatal outcome may include stillbirth, preterm delivery, or neonatal death.