Development:
This type of placenta is developed bcz of the smalll size of the chorionic plate than tha basal plate. In this the chorionic plate doesn’t extend to the margin of the placenta. Because of that there happens recurrent marginal hemmorage. In this the chorion and amnoin are folded back and forms a ring ….. which leaves behind a bare PLACENTAL tissue and that is extrachorial placeta.
Two types:
Circumvallate placenta:
The depressed fetal zone is covered by a thick membrane which is complete circumscribed. The membranes which encircles the fetal zone is composed of chorion, amnion , degenerated part of decidua Vera and fibrins. The vessels which is radiating from the cord insertion site which leads to ring and then disappear. The peripheral zone outside the ring is thicker and the edges are round and elevated.
Placeta marginata:
In this the ring is formed at the margin of the chorionic plate and is the fetal vessels are appears to terminate.
Clinical significance:
- Abortion
- Antepartum hemorrhage
- Growth retardation
- Preterm delivery
- Retained bits of placenta
- Hydrorrhea gravidarum
Placenta fenestra:
This is due to the missing of the central portion of the placenta….this is due to the retaining of the central cotylden in the uterus.
Placenta succenturiata:
In this case a accessory lobe is formed from villi of the chorionic laeve from the the margin of the placenta, and is connected by the blood vessels. If the blood vessels are absent it is called placeta spuria.
Clinical significance:
- Postpartum hemmorage
- Uterine sepsis
- Polyp formation
- Subinvolution of uterus
Placeta bilobate:
In this two equally sized placental lobes are formed and is connected to the chorionic plate or to the intervening membranes between the placental lobes.
Clinical significance is same as the placenta succenturiata.
