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.
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