Definition: 'Placenta Circumvallata'
placenta circumvallataType: Term
1. a cup-shaped placenta with raised edges, having a thick, round, white, opaque ring around its periphery; a portion of the decidua separates the margin of the placenta from its chorionic plate; the remainder of the chorionic surface is normal in appearance, but the fetal vessels are limited in their course across the placenta by the ring.
The definition information for placenta circumvallata is provided by Stedman's. You can search our medical dictionary here.