| Circumvallate Placenta | |
|---|---|
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| The thickened ring of membranes on the fetal surface of a circumvallate placenta, making it appear as though the central part of the placenta has been exposed. | |
| Specialty | Obstetrics  |
Circumvallate placenta is a rare condition affecting about 1-2% of pregnancies, in which the amnion and chorion fetal membranes essentially "double back" on the fetal side around the edges of the placenta.[1] After delivery, a circumvallate placenta has a thick ring of membranes on its fetal surface.[2] Circumvallate placenta is a placental morphological abnormality associated with increased fetal morbidity and mortality due to the restricted availability of nutrients and oxygen to the developing fetus.
Physicians may be able to detect a circumvallate placenta during pregnancy by using an ultrasound. However, in other cases, a circumvallate placenta is not identified until delivery of the baby. Circumvallate placenta can increase the risk of associated complications such as preterm delivery and placental abruption. Occasionally, a circumvallate placenta can also increase the risk of neonatal death and emergency caesarean section. Although there is no existing treatment for circumvallate placenta, physicians can attempt to minimize the effects of complications, if they occur, through frequent fetal monitoring and, if necessary, emergency cesarean section.[1]
In a circumvallate placenta, the chorionic plate, which forms the fetal surface of the placenta, tends to be smaller than the basal plate, which forms the maternal surface of the placenta. This results in the elevation of the placental margin and the appearance of an annular shape.[3] The fetal surface is divided into a central depressed zone surrounded by a thickened white ring which is incomplete. The ring is situated at varying distances from the margin, or edges, of the placenta. This thick ring of membranes is composed of a double fold of amnion and chorion with degenerated decidua vera and fibrin in between. Blood vessels, supplying nutrients and carrying waste products to and from the developing fetus, radiate from the umbilical cord insertion to as far as the ring of membranes, and then disappears from view.[4]
- ^ a b "Circumvallate placenta: Risks, causes, and treatment". www.medicalnewstoday.com. 2020-03-09. Retrieved 2022-11-07.
- ^ Yetter, Joseph F (1998). "Examination of the Placenta". American Family Physician. 57 (5): 1045–54. PMID 9518951.
- ^ Dukatz, Ricarda; Henrich, Wolfgang; Entezami, Michael; Nasser, Sara; Siedentopf, Jan-Peter (2020-01-01). "Circumvallate placenta and abnormal cord insertion as risk factors for intrauterine growth restriction and preterm birth: a case report". Case Reports in Perinatal Medicine. 9 (1). doi:10.1515/crpm-2020-0020. ISSN 2192-8959.
- ^ Harris, R D; Wells, W A; Black, W C; Chertoff, J D; Poplack, S P; Sargent, S K; Crow, H C (1997-06-01). "Accuracy of prenatal sonography for detecting circumvallate placenta". American Journal of Roentgenology. 168 (6): 1603–1608. doi:10.2214/ajr.168.6.9168736. ISSN 0361-803X. PMID 9168736.