Module 9 : Normal Fetal Anatomy - Placenta and Cord Flashcards

1
Q

at what week do we see two distinct components o the placenta

A

12 weeks

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2
Q

two distinct components of the placenta

A

chorion frondosum

decidua basalis

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3
Q

chorion frondosum

A

fetal portion

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4
Q

decidua basalis

A

maternal portion

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5
Q

how are the two layers held together

A
  • anchoring or stem villi at the cytotrophoblastic shell
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6
Q

intervilluous spaces

A
  • syncytiotrophoblast cells create large spaces in the decidua basalis
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7
Q

placental septa

A
  • remaining projections of the decidua basalts

- septa divide the placenta into compartments

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8
Q

cotyledon

A
  • each compartment the septa divide into in the placenta
  • consist of several stem villi
  • about twenty in a placenta
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9
Q

placenta membrane

A
  • separates the fetal blood in the capillaries of the CHORIONIC VILLI from the maternal blood in the INTERVILLOUS SPACES
  • maternal blood enters the intervillous spaces via the spiral arterioles
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10
Q

maternal circualtion

A
  • spiral arterioles shoot blood around the chorionic villi
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11
Q

fetal circulation

A
  • from umbilical arteries to chorionic villi back to umbilical veins to baby
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12
Q

functions of the placenta

A
  • respiration (exchange oxygen)
  • nutrition
  • excretion (carbon dioxide)
  • protection (toxic elements)
  • storage
  • hormonal production
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13
Q

sonographic appearance

A
  • early = homogenous
  • venous lakes along the basal plate and in the septa
  • may see calcifications later in pregnancy due to maternal serum calcium levels
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14
Q

grading of placenta

A
  • grade 0 - 3
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15
Q

grade 0 placenta

A
  • homogenous

- chorionic plate is straight

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16
Q

grade 1 placenta

A
  • scattered echogenic areas

- subtle undulations

17
Q

grade 2 placenta

A
  • indentations

- linear echogenic areas

18
Q

grade 3 placenta

A
  • indentations to basal layer
  • cystic areas
  • shadowing calcifications
  • after 36 weeks
19
Q

placenta shape

A
  • flat and circular
20
Q

weight of placenta a

A
  • 500-600 grams at term
21
Q

thickness of placenta

A

1.5-4 cm

22
Q

abnormal placenta thickness

A

> 4 cm

23
Q

growth of placenta per day

A

1mm

24
Q

measuring placenta

A
  • do not include retroplacenta complex (basal layer)
25
Q

placentamegaly

A

> 4cm thick

26
Q

causes of placentamegaly

A
  • maternal diabetes
  • maternal anemia
  • hydrops
  • placenta hemorrhage
  • intrauterine infection
  • partial mole
  • chromosomal abnormalities
27
Q

complete molar pregnancy

A
  • triploidy 69 chromosomes
  • uterus full of placenta
  • no embryo
  • if not removed can lead to chorionic carcinoma
28
Q

thin placenta

A
  • placenta insufficiency
  • may cause IUGR
  • < 1.5 cm
29
Q

causes of thin placenta

A
  • vascular deficiencies or infarction

- pre eclampsia = a toxaemia of late pregnancy (hypertension, protein urie, edema)

30
Q

contraction vs fibroid

A
- fibroid
   \+ muscular tumor benign 
   \+ lasts long time
- contraction 
   \+ Braxton hicks
   \+ will go away after time
31
Q

umbilical cord

A
  • develops from connecting stock and yolk sac
  • 2 arteries 1 vein
  • vessels surrounded by whartons jelly
  • covered with amnion
  • 50-100 cm long
32
Q

attachment of cord

A
  • usually centre of placenta
  • umbilical vein travels cephalic to portal sinus
  • umbilical arteries travel caudal around fetal bladder to hypogastric arteries in fetus
33
Q

single umbilical artery

A
  • associated with cardiac and renal anomalies
  • associated with chromosomal abnormalities
  • often isolated finding and very common
34
Q

other cord anomalies

A
  • hematoma
  • cord cyst
  • umbilical vein thrombosis
  • omphalocele
  • cord prolapse
35
Q

hematoma

A
  • from trauma of wall weakness

- results in perinatal death

36
Q

cord cyst

A
  • allantoid remnant

- insignificant

37
Q

umbilical vein thrombus

A
  • umbilical vein varix (dilation) or blockage

- results in perinatal death

38
Q

omphalocele

A
  • liver outside of abdomen
39
Q

cord prolapse

A
  • cord slips into cervix and vagina

- NOT GOOD