Chapter 56 Placenta

Permits the exchange of oxygenated maternal blood with deoxygenated fetal blood

placenta

The placenta can be see as early as what week

week 7

What are the two components of the placenta

Chorion frondosum

Decidua basalis

fetal portion of the placenta

chorion frondosum

maternal portion of the placenta

decidua basalis

What is the major functioning unit of the placenta

chorionic villis

What are within the chorionic villus

intervillous spaces

What is the maternal surface

basal plate

How does fetal umbillical circulation originate

With deoxygenated blood from the heart through the ductus arterious into the aorta

What arteries does the fetal blood circulate

hypogastric arteries to the umbillical arteries to the umbillical cord

where is 40% of fetal cardiac output directed through

umbilical circulation

Umbilical arteries divide within the placenta into

multiple tiny capillaries that branch into the tertiary villi

Where is oxygenated blood brought to the placenta by

80-100 branches of the uterine arteries spiral arteries

Maternal blood returns through a network of

basilar, subchorial, interloblar, and marginal veins

How is the fetal placenta attached to the maternal placenta

cytotrophoblastic shell and anchoring villi

insertion at the placental margin

battledore

insertion into the membrane

may cause hemorrhage if the vessel is postioned over the internal os

velamentous

responsible for the transfer of nutrients to the embryo until the plaenta takes over

yolk sac

condition when the placenta implants too close to the internal os

placenta previa

What day does the amnion develop and attaches to the embyronic disk

day 28

originates from trophoblastic cells and remains in contact with the trophoblasts throughout the pregnancy

chorion

expansion of the amniotic cavity occurs with increase in

amniotic fluid

By what week do the amnion and chorion fuse and are no longer seen

week 16

If the chorion and amnion are not fused by 16 weeks what should you evaluate for

abnormal amount of fluid

When does the umbilical cord form

first 5 weeks

what surrounds the umbilical cord

whartons jelly

bowel herniates into the umbilical cord (gastroschisis) from what week

week 7-10

What is the largest vessel in the umbilical cord

the vein

One umbilical artery is found in waht percent of single ton births

1%

What can be confused with normal placenta

braxton hicks contractions

very common

large vessels that appear cystic behind the chronic plate and between the chorionic plate and between the chorion and amnion filled with maternal blood

venous lakes

occurs when the placenta lies on both the anterior and posterior walls and does not communicate

succenturiate placenta

grade of placenta that is uninterrupted chorionic plate and homogenous placental substance

grade 0

grade of placenta with subtle indentations in the chorionic plate and some small calcification

grade 1

grade of placenta with moderate indentations in the chorionic plate with comma like calcifications

grade 2

grade of placenta with prominent indentation in the chorionic plate that extends to the basal layer and echogenic and anechoic areas within the placenta

grade 3

grade 0

what grade placenta is seen late 1st- early 2nd

grade 0

what grade placenta is seen mid 2nd-early 3rd

grade1

grade 1

what grade placenta is seen late 3rd

grade 2

what grade placenta is seen 39- post due date

grade 3

grade 2

grade 3

type of arteries that are low resistant on doppler

trophoblastic spiral arteries

are variable with gestational age and location

uterine arteries

flow measurements will decrease with

gestational age

Normal diameter of the placenta

15-20 cm

normal thicken of placenta

4 cm

approx weight of placenta

600g

protein derived from fibrogen

found throughout the placenta and septa

fibrin deposition

appears as hypoechoic area beneath the chorionic plate of the placenta

fibrin deposition