C9: Norm Fetal Anatomy- Placenta And Cord Flashcards

1
Q

What are the 2 components of the placenta (maternal and fetal portion)

A

Maternal: Decidua Basalis
Fetal: Chorion frondosum

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2
Q

When are the 2 layers of the placenta distinguishable

A

12 wks

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3
Q

How are the 2 parts of the placenta held together and where

A

By anchoring or stem villi at the cytotrophoblastic shell

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4
Q

What do the syncytiotrophoblast cells create in the decidua basalis

A

Intervillous spaces

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5
Q

What are the remaining projections of the decidua basalis?

A

Placental septa

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6
Q

Whats the function of the placental septa

A

Divides the placenta into compartments

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7
Q

What are the compartments of the placenta called?

How many in a placenta

A

Cotyledon, which consist of several stem villi

About 20

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8
Q

What’s the function of the placental memebrane

A

Separates the fetal blood in the capillaries of the chorionic villi from the maternal blood in the intervillous spaces

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9
Q

How does maternal blood enter the intervillous spaces

A

Spiral arterioles

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10
Q

How does maternal circulation flow in the placenta

A

Spiral arterioles carry blood around the chorionic villi

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11
Q

How does fetal circulation flow in the placenta

A

From the umbilical arteries to the chorionic villi and back to the umbilical vein and then to baby

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12
Q

List the functions of the placenta

A
  1. Oxygenation/respiration
  2. Nutrition
  3. Excretion
  4. Protection
  5. Storage
  6. Hormonal production
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13
Q

How does the placenta appear on US

A

Homogenous

  • will have venous lakes along the basal plate in the septa
  • may see calcification in late pregnancy
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14
Q

What are maternal lakes

A

Blood pooling behind the placenta

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15
Q

What are the placental grades and how do they each appear?

A

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.

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16
Q

When do all placentas turn to a Grade 3

A

After 36 weeks

17
Q

Describe the shape and size of the placenta

How much should it grows in a wk

A

Flat and circular
Thickness should be 1.5-4 cm

-grows 1mm a wk in thickness

18
Q

What placental thickness is abnormal

A

4 cm is abnormal

19
Q

What etiology causes Placentamegaly

what measurement indicates Placentamegaly

A
Maternal diabetes
Maternal anemia
Hydros
Placental hemorrhage
Intrauterine infection
Partial Mole
Chromosomal Abnormalities 

> 4 cm thick

20
Q

what is a complete molar pregnancy

when does it occur?

A
  • when no embryo develops, uterus is full of placental tissue… will have very high levels of bhCG
  • occurs w/ triploidy (69 chromo)
21
Q

what does a thin placenta indicate about placental functions?
what are the causes of a thin placenta

A

-placetal insufficicency

+caused by:

  • vascular deficiencies or infarction
  • pre-eclampsia/toxemia
22
Q

what can a thin placenta cause?

with what measurement would it be considered thin

A

IUGR

< 1.5 cm

23
Q

where are fibroids typically found

A

outside of the uterus

24
Q

from which structures does the umbilical cord develop from

A

Allantois which is an out pouch of the yolk sac

25
Q

what is the umbilical cord surrounded by and covered with?

how long is it

A

surrounded by Whartons Jelly for protection and covered in amnion

50-100 cm

26
Q

the umbilical arteries travel caudad around which structure and connect to which arteries?

A
  • around the bladder

- connect to the hypogastric arteries

27
Q

the umbilical vein travels cephalad to which structure?

A

portal sinus

28
Q

a single umbilical artery is associated with what abnormalities?

is it common? is it usually an isolated finding

A
  • cardiac, chromosomal and renal abnormalities

- very common, usually an isolated finding

29
Q

what are 5 umbilical cord anomalies that can occur… what are there causes and outcomes

A

-hematoma
+ from trauma or wall weakness
+ leads to death of fetus

-cord cyst
+ allantoid remnant
+ insignificant

  • umbilical vein thrombus
    + can cause umbilical vein varix or blockage
    + leads to death of fetus

-omphalocele
+ leads to death of fetus

  • cord prolapse
30
Q

what is an umbilical vein varix

A

widening of UV as it inserts into babies abdomen… baby will likely be delivered early

31
Q

Do you include the retroplacental complex (basal layer) when measuring the placental thickness?

A

No