B8.021 Prework 1: Placental Insufficiency

Question 1

what is histotrophic nutrition

Answer 1

occurs during weeks 0-13 of gestation

blastocyt embeds in uterine wall and receives nutrition from maternal blood bathing it via lacunae

Question 2

oxygen concentration in histotrophic nutrition

Answer 2

low

Question 3

hemotrophic nutrition

Answer 3

> 13 weeks gestation
maternal circulation can feed placenta/fetus through a more complex network
more exchange of oxygen and nutrients

Question 4

histotrophic to hemotrophic transition

Answer 4

spiral artery remodeling: replacement of artery smooth muscle with fibrinoid material
increasingly dense branching of villi to accommodate increased demand for exchange

Question 5

action of fetal capillaries throughout gestation

Answer 5

9-23 weeks: angiogenesis

23-24 weeks: peak angiogenesis

Question 6

3 primary components of uteroplacental circulation

Answer 6

arterial circulation
venous drainage
circulation in intervillous space

Question 7

umbilical arteries

Answer 7

2 arteries, each supplying 1/2 of placenta
primary, secondary, and teriary branches in chorionic villi
carry deoxygenated blood from fetus to placenta

Question 8

umbilical vein

Answer 8

thin walled

carries oxygenated blood from placenta to fetus

Question 9

what is placental insufficiency

Answer 9

inadequate supply of nutrients and oxygen to the fetus

Question 10

what is the net placental transport composed of

Answer 10

uteroplacental and umbilical blood flows
placental exchange area and metabolism
placental nutrient transporters

Question 11

evidence for placental insufficiency

Answer 11

fetal blood flow
structural integrity
appearance
maternal blood flow

Question 12

how is fetal blood flow evaluated

Answer 12

umbilical artery doppler

baby’s blood flow to placenta

Question 13

how is maternal blood flow evaluated

Answer 13

uterine artery doppler

mother’s blood flow to placenta

Question 14

disruption of uteroplacental contact

Answer 14

results in placental blood loss and inadequate exchange

blood can build up between placenta and uterine wall

Question 15

ideal structure of placenta

Answer 15

large surface area = greater opportunity for gas and nutrient exchange
long and thin is better than thick and small
want it spread over as much of the uterus as possible

Question 16

function of spiral arteries when not pregnant

Answer 16

supply blood to uterine lining

Question 17

changes in spiral arteries during pregnancy

Answer 17

trophoblast invasion, remodeling, and expansion

replaces capillary endothelium to create a low pressure, high flow to the placenta

Question 18

what can cause deficient spiral artery remodeling

Answer 18

inadequate histotrophic nutrition
excessive apoptosis
poor invasion

Question 19

result of malperfusion in the placenta

Answer 19

ischemia and increased oxidative stress result

oxidative stress generates highly reactive species of oxygen which overwhelms the cell’s capacity to detoxify them

Question 20

biochemical findings in placental insufficiency

Answer 20

trophoblast damage can alter the integrity of the barrier and allow various proteins to leak out of the fetal circulation into the mother’s blood

• PAPP-A
• AFP
• hCG
• DIA

Question 21

pregnancy associated plasma protein

Answer 21

PAPP-A

amount in maternal blood reflects the size of the “footprint” of the placenta on the uterine wall

Question 22

AFP

Answer 22

made by fetal liver

high = leaky or damaged placenta

Question 23

hCG

Answer 23

elevated levels signal abnormal placental development and function of the syncytiotrophoblast

Question 24

inhibin

Answer 24

DIA

dual elevation of hCG and DIA poses a very high risk of severe preeclampsia which is a risk factor for IUGR

Question 25

2 primary histo characteristics of placental insufficiency

Answer 25

fibrinoid deposit = injury to villi

syncytial knots = syncytiotrophoblast apoptosis, represents maldevelopment of villous tree

Question 26

2 membranes of syncytiotrophoblasts

Answer 26

microvillous - faces intervillous space

basal - faces fetal capillaries

Question 27

signaling pathways in placenta

Answer 27

mTOR signaling integrates nutrient availability from mother to regulate fetal growth

Question 28

decrease in mTOR signaling

Answer 28

IUGR

Question 29

variability in size, shape, and texture of placenta

Answer 29

decreased efficiency of exchange
variations:
succenturiate
velamentous
battledore
circumvallate

Question 30

umbilical cord insertion abnormalities

Answer 30

should be central

if not, can have negative hemodynamic effects