Placenta

Question 1

after implantation the trophoblast begins to differentiate into two cell layers:

Answer 1

the outer syncytiotrophoblast and the inner cytotrophoblast.

Question 2

As the trophoblast invades the decidua, it breaks down decidual blood filled spaces known as

Answer 2

lacunae

Question 3

network of lacunae evolves into

Answer 3

intervillous spaces of the placenta.

Question 4

normal appearance of placenta (3)

Answer 4

Relatively homogeneous
Retroplacental clear space is hypoechoic
Venous laking

Question 5

what are placental venous lakes

Answer 5

formation of hypoechoic cystic spaces centrally within the placenta

Question 6

is there flow within the placental lakes

Answer 6

low-velocity intraplacental laminar flow

Question 7

what are placental lakes associted with

Answer 7

increased placental thickness
placenta accreta spectrum and abnormal placental villous adherence
placental insufficiency, especially if seen early in pregnancy

Question 8

normal placenta attaches to

Answer 8

the decidua basalis

Question 9

In the 1st and 2nd trimester sonograms will show what placenta

Answer 9

a low lying placenta or placenta previa that will convert to a normal higher position when re-evaluated in the 3rd trimester

Question 10

low lying placenta moving known as

Answer 10

“placental migration or retraction”

Question 11

what is placenta migration due to

Answer 11

to differential growth rates between the uterus and placenta

Question 12

< ______ cm abnormal at 20 weeks for placenta length

Answer 12

<14cm

Question 13

< _______ cm abnormal at 23 weeks for placenta length

Answer 13

<15cm

Question 14

> ______ cm abnormal at 20 weeks for placenta thickness

Answer 14

> 3 cm

Question 15

> ______ cm abnormal at 23 weeks for placenta thickness

Answer 15

> 4cm

Question 16

cord should be inserted where on the placenta

Answer 16

Middle

Question 17

what are are succenturiate lobes

Answer 17

single or multiple lobes connected to the main body of placenta by velamentous connection of the umbilical vessel (vessels traversing the membrane).

Question 18

what is the concern of not seeing the accessory lobe?

Answer 18

that the lobe may be retained after delivery

Question 19

what is bilobed placenta

Answer 19

It is referred to two similarly sized placental lobes separated by intervening membrane. May still have vasculature across membrane

Question 20

what is Velamentous cord insertion

Answer 20

abnormal condition during pregnancy
umbilical cord inserts into the fetal membranes (choriamniotic membranes), then travels within the membranes to the placenta (between the amnion and the chorion).

Question 21

what is CIRCUMVALLATE PLACENTA

Answer 21

fetal membranes (chorion and amnion) "double back" on the fetal side around the edge of the placenta.
chorionic plate is smaller then the basal plate (normal variant)

Question 22

What is circumvallate placenta associated with

Answer 22

associated with increased chances of placental abruption and hemorrhage
usually no harm tho

Question 23

free margin of the circumvallate placenta can mimic

Answer 23

a fetal membrane

Question 24

Placenta membranacea aka

Answer 24

placenta diffusa

Question 25

what is Placenta membranacea

Answer 25

all or most fetal membranes remain covered by chorionic villi, because the chorion has failed to differentiate into chorion leave and chorion frondosum.

Question 26

sono appearance of Placenta membranacea

Answer 26

placenta that is covering most or the entire uterine wall

Question 27

What is placenta previa

Answer 27

placenta that partially or completely covers the internal os.

Question 28

marginal previa is

Answer 28

interal os is partially covered

Question 29

low lying placenta is

Answer 29

placental the edge is within 2 cm but not covering any portion of the internal os

Question 30

main risk factor of placenta previa

Answer 30

bleeding

Question 31

when is placenta previa usually not asymptomatic

Answer 31

the time of labour and delivery

Question 32

is it easier to see placenta previa/low lying placenta in 2nd/3rd trimester

Answer 32

no more difficult as time goes on, fetal parts get in the way of seeing it

Question 33

Most significant factors contributing to the relatively high false positive diagnosis of Placenta Previa are (2)

Answer 33

Distortion of lower segment (by over distended bladder)

Focal myometrial contractions

Question 34

first modality for imaging placenta previa

Answer 34

US