Placenta membranacea

Placenta membranacea, also known as a placenta diffusa, is an extremely uncommon variation in placental morphology in which placenta develops as a thin membranous structure occupying the entire periphery of the chorion.

The estimated incidence is at ~1:20000-40000 pregnancies 1.

In this situation all of the fetal membranes are covered by functioning villi and the placenta develops as a thin membranous structure occupying the entire periphery of the chorion. The placental mass can be often thin (1-2 cm 7,8) and even disrupted.

Associations
Antenatal ultrasound

May be seen as a placenta which circumferentially covers most (partial) or all (complete) of the entire uterine wall. May also show accompanying placental thinning and/or disruption.

Recognised complications include:

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Article Information

rID: 13473
System: Obstetrics
Section: Pathology
Tag: cases
Synonyms or Alternate Spellings:
  • Placenta diffusa

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Cases and Figures

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    Placenta membranacea
    Figure 1: diagram - placenta membranacea
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