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.
- abnormal placental adherence: reported in up to 30% of cases 1
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:
- 1. Greenberg JA, Sorem KA, Shifren JL et-al. Placenta membranacea with placenta increta: a case report and literature review. Obstet Gynecol. 1991;78 (3 Pt 2): 512-4. - Pubmed citation
- 2. Wilkins BS, Batcup G, Vinall PS. Partial placenta membranacea. Br J Obstet Gynaecol. 1991;98 (7): 675-9. - Pubmed citation
- 3. Ahmed A, Gilbert-barness E. Placenta membranacea: a developmental anomaly with diverse clinical presentation. Pediatr. Dev. Pathol. 6 (2): 201-2. doi:10.1007/s10024-002-0007-z - Pubmed citation
- 4. Molloy CE, Mcdowell W, Armour T et-al. Ultrasonic diagnosis of placenta membranacea in utero. J Ultrasound Med. 1983;2 (8): 377-9. J Ultrasound Med (citation) - Pubmed citation
- 5. Hurley VA, Beischer NA. Placenta membranacea. Case reports. Br J Obstet Gynaecol. 1987;94 (8): 798-802. - Pubmed citation
- 6. Baergen RN, Benirschke K(. Manual of Pathology of the Human Placenta. Springer Verlag. (2010) ISBN:1441974938. Read it at Google Books - Find it at Amazon
- 7. Benirschke K, Kaufmann P. Pathology of the human placenta. Springer Verlag. (2000) ISBN:0387988947. Read it at Google Books - Find it at Amazon
- 8. Prayer D. Fetal MRI. Springer Verlag. (2010) ISBN:3540732705. Read it at Google Books - Find it at Amazon
- placental anatomy
- placental developmental abnormalities
- placenta previa
- spectrum of abnormal placental villous adherence
- abnormalities of cord insertion
- abruptio placentae
- placental pathology
- vascular pathologies of placenta
- placental infections
- placental masses
- molar pregnancy
- twin placenta