C9: Norm Fetal Anatomy- Placenta And Cord Flashcards
(31 cards)
What are the 2 components of the placenta (maternal and fetal portion)
Maternal: Decidua Basalis
Fetal: Chorion frondosum
When are the 2 layers of the placenta distinguishable
12 wks
How are the 2 parts of the placenta held together and where
By anchoring or stem villi at the cytotrophoblastic shell
What do the syncytiotrophoblast cells create in the decidua basalis
Intervillous spaces
What are the remaining projections of the decidua basalis?
Placental septa
Whats the function of the placental septa
Divides the placenta into compartments
What are the compartments of the placenta called?
How many in a placenta
Cotyledon, which consist of several stem villi
About 20
What’s the function of the placental memebrane
Separates the fetal blood in the capillaries of the chorionic villi from the maternal blood in the intervillous spaces
How does maternal blood enter the intervillous spaces
Spiral arterioles
How does maternal circulation flow in the placenta
Spiral arterioles carry blood around the chorionic villi
How does fetal circulation flow in the placenta
From the umbilical arteries to the chorionic villi and back to the umbilical vein and then to baby
List the functions of the placenta
- Oxygenation/respiration
- Nutrition
- Excretion
- Protection
- Storage
- Hormonal production
How does the placenta appear on US
Homogenous
- will have venous lakes along the basal plate in the septa
- may see calcification in late pregnancy
What are maternal lakes
Blood pooling behind the placenta
What are the placental grades and how do they each appear?
Grade 0: homogenous, straight chorionic plate
Grade 1: scattered echogenic area, subtle undulations
Grade 2: indentations that don’t go all the way to the basal layer and linear echogenic areas
Grade 3: indentations to basal layer, cystic areas and shadowing calcification.
When do all placentas turn to a Grade 3
After 36 weeks
Describe the shape and size of the placenta
How much should it grows in a wk
Flat and circular
Thickness should be 1.5-4 cm
-grows 1mm a wk in thickness
What placental thickness is abnormal
4 cm is abnormal
What etiology causes Placentamegaly
what measurement indicates Placentamegaly
Maternal diabetes Maternal anemia Hydros Placental hemorrhage Intrauterine infection Partial Mole Chromosomal Abnormalities
> 4 cm thick
what is a complete molar pregnancy
when does it occur?
- when no embryo develops, uterus is full of placental tissue… will have very high levels of bhCG
- occurs w/ triploidy (69 chromo)
what does a thin placenta indicate about placental functions?
what are the causes of a thin placenta
-placetal insufficicency
+caused by:
- vascular deficiencies or infarction
- pre-eclampsia/toxemia
what can a thin placenta cause?
with what measurement would it be considered thin
IUGR
< 1.5 cm
where are fibroids typically found
outside of the uterus
from which structures does the umbilical cord develop from
Allantois which is an out pouch of the yolk sac
