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DMS 400 OB/GYN > Class 14: Placenta > Flashcards

Class 14: Placenta Flashcards

1
Q

shape of placenta

A

disc shaped

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2
Q

size of placenta at term

A

500-600g

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3
Q

2 compartments of the placenta?

A
  1. fetal side
  2. maternal side
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4
Q

where is the fetal side of the placenta?

A

choroid/chorionic plate with chorionic villi at the site of implantation

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5
Q

where is the maternal side of the placenta?

A

side of decidua basilis with cotyledons

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6
Q

function of the placenta?

A
  • works as fetal lungs
  • exchanges blood and nutrients bw mother & fetus
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7
Q

what is the functioning unit of the placenta?

A

chorionic villi

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8
Q

4 locations a placenta can be in the uterus

A
  1. anterior
  2. posterior
  3. lateral
  4. fundal
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9
Q

how thick can a normal placenta be?

A

1.5-5cm

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10
Q

what can a placenta less than 1.5 cm indicate?

A

IUGR or preeclampsia

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11
Q

what can a placenta over 5 cm inidicate?

A

maternal diabetes or fetal hydrops

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12
Q

what trimester can venous lakes be seen in?

A

2nd or 3rd

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13
Q

what are venous lakes?

A

intraplacental & subchorionic anechoic spaces

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14
Q

where is the retroplacental complex?

A

behind the placenta

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15
Q

what does the retroplacental complex consist of?

A

decidua basilis, some myometrium, maternal vasculature

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16
Q

U/S appearance of retroplacental complex

A

horizontal echoes

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17
Q

3 types of cord insertion into the placenta

A
  1. central
  2. battledore
  3. velamentous/membranous
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18
Q

where does a central cord insertion attach to?

A

near the center of the placenta

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19
Q

where does a battledore cord insertion attach to?

A

towards the edge of the placenta

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20
Q

where does a velamentous/membranous cord insertion attach to?

A

cord inserts into membranes before entering the placenta

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21
Q

what is a velamentous cord insertion associated with?

A

IUGR/FGR due to placenta insufficiency

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22
Q

___% of placentas have calcification after ___ weeks

A

50%; 33 weeks

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23
Q

U/S appearance of placental calcification?

A

hyperechoic foci without shadowing

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24
Q

what placental grades are normal until term?

A

grade 1,2,3

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25
Q

what grade is this placenta?
smooth chorionic plate, homogenous placenta, no calcification

A

grade 0

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26
Q

it is abnormal to see grade 0 placenta after ___ weeks

A

30 weeks

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27
Q

what does a grade 0 placenta after 30 weeks indicate?

A

maternal diabetes or fetal hydrops

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28
Q

what grade is this placenta?
chorionic plate starts forming indentations, placenta is developing echogenic foci

A

grade 1

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29
Q

what weeks does a grade 1 placenta start developing?

A

~ 31-36 weeks

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30
Q

what grade is this placenta?
chorionic plate develops more folds and the basal plate now has calcifications

A

grade 2

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31
Q

what weeks does a grade 2 placenta start developing?

A

~ 36-38 weeks

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32
Q

what grade is this placenta?
complete indentation of chorionic plate, basal calcifications now have interlobar septal calcifications, and venous lakes in intervillous spaces

A

grade 3

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33
Q

grade 3 before ___ weeks can indicate IUGR/FGR or maternal preeclampsia

A

35 weeks

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34
Q

what size is considered placentamegaly?

A

> 5 cm

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35
Q

most common cause of placentamegaly?

A

maternal diabetes

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36
Q

what is beckwith-wiedman syndrome?

A

congenital overgrowth syndrome

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37
Q

what size placenta is associated with beckwith-wiedman syndrome

A

placentamegaly

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38
Q

what size is considered placental insufficiency?

A

< 1.5 cm

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39
Q

4 abnormal placenta shapes?

A
  1. bilobed/bipartite
  2. succenturiate lobe
  3. annular placenta
  4. placenta membranacia/diffusa
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40
Q

what is a bilobed placenta?

A

placenta with 1 anterior lobe & 1 posterior lobe

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41
Q

what is a succenturiate placenta?

A

placenta with an accessory placenta

42
Q

risk of having a succenturiate placenta?

A

post partum hemorrhage if accessory placenta is undelivered

43
Q

what is an annular placenta?

A

a ring-shaped placenta

44
Q

what placental abnormality is associated with an annular placenta?

A

placenta previa

45
Q

what is a placenta membranacea/diffusa?

A

a placenta develops as a thing membranous structure with chorionic villi stretching all around

46
Q

what is placenta previa?

A

an abnormal placenta that partially or completely covers the internal-os

47
Q

what is the most common cause of painLESS bleeding in the 3rd trimester?

A

placenta previa

48
Q

4 types of placenta previa?

A

complete, partial, marginal, low-lying

49
Q

what is complete placenta previa?

A

placenta covers entire internal-os & is attached on both sides of UT

50
Q

what is partial placenta previa?

A

placenta partially covers internal-os

51
Q

what is marginal placenta previa?

A

placenta’s edges touch the margins of internal-os

52
Q

what is a low-lying placenta?

A

placenta that is in the lower uterine segment

53
Q

how close does a placenta have to be from internal-os to be considered low lying?

A

2 cm away from internal-os

54
Q

what weeks does diagnosing placenta previa usually occur in?

A

34-36 weeks unless over 1/3 covers the internal-os

55
Q

why does diagnosis of placenta previa not occur until later in pregnancy?

A

placental migration

56
Q

the following are risk factors for what placental abnormality?
advanced maternal age, previous c-section, multiple gestations, cocaine use, smoking, multiparity, and uterine scarring

A

placenta previa

57
Q

what are 3 complications of placenta previa?

A

post partum hemorrhage
preterm labor
bleeding

58
Q

what type of imaging is most commonly used with placenta previa?

A

transvaginal

59
Q

what is placental abruption?

A

the premature separation of all or part of placenta from myometrium

60
Q

why is placental abruption a medical emergency?

A

it can cause catastrophic hemorrhage

61
Q

what is the most common painful bleeding in the 3rd trimester?

A

placental abruption

62
Q

the following may cause what placental abnormality?
advanced maternal age, trauma, short umbilical cord, maternal HTN, maternal vascular disease

A

placental abruption

63
Q

2 types of placental abruption

A
  1. marginal
  2. retroplacental
64
Q

what causes marginal placental abruption? is it low or high pressure bleeding?

A

tears of marginal veins cause low pressure bleeding

65
Q

marginal placental abruption is associated with vascular disease and hypertension. T/F?

A

false – it is associated with cigarette smoking

66
Q

what causes retroplacental abruption and what type of bleeding can it cause?

A

spiral arteries rupture and can cause high pressure bleeding

67
Q

there is visible bleeding with retroplacental abruption. T/F?

A

false – no visible bleeding

68
Q

what maternal conditions are associated with retroplacental abruption?

A

HTN & vascular disease

69
Q

what is placental attachment disorder?

A

placenta attaches abnormally to uterine wall due to defect in decidua basilis

70
Q

3 types of placental attachment disorders?

A
  1. placenta accreta
  2. placenta increta
  3. placenta percreta
71
Q

what is placenta accreta?

A

PAD where chorionic villi is in direct contact with myometrium

72
Q

what is placenta increta?

A

PAD where chorionic villi infiltrate myometrium

73
Q

what is placenta percreta?

A

PAD where chorionic villi infiltrate perimetrium & possibly other organs

74
Q

what may be the cause of PAD?

A

uterine scarring

75
Q

what other placental abnormality is present with PAD?

A

placenta previa

76
Q

what is the preferred imaging modality for PAD?

77
Q

2 placental tumors?

A
  1. chorioangioma
  2. teratoma
78
Q

what is the most common benign placental tumor?

A

chorioangioma

79
Q

what is a chorioangioma?

A

a vascular malformation of the placenta

80
Q

complications of chorioangioma?

A

IUGR
fetal hydrops
fetal demise
premature labor

81
Q

teratomas of the placenta are rare. T/F?

82
Q

U/S appearance of teratoma?

A

complex appearance

83
Q

what is the umbilical cord composed of?

A

1 vein & 2 spiral arteries surrounded by wharton’s jelly, which is enclosed by a layer of amnion

84
Q

when is the umbilical cord best seen?

A

2nd and 3rd trimesters

85
Q

what is the normal length of the umbilical cord at term?

A

about 55 cm; ranges 30-120 cm

86
Q

U/S appearance of the umbilical cord in TRV?

A

TRV: mickey mouse sign

87
Q

what is a nuchal cord?

A

an umbilical cord that is looped at least once around fetus’ neck

88
Q

complications of nuchal cord?

A

usually clinically insignificant, but can cause:
decrease fetal breathing, movement, and birth weight
meconium staining

89
Q

what can meconium staining cause?

A

respiratory problems for the fetus

90
Q

3 types of umbilical cord prolapse?

A
  1. occult/hidden
  2. frank
  3. vasa previa
91
Q

what is an occult/hidden umbilical cord prolapse?

A

the cord is near presenting fetal part

92
Q

what is a frank prolapse of the umbilical cord?

A

the cord protrudes into the cervix and has ruptured membranes

93
Q

what is a vasa previa prolapse of the umbilical cord?

A

the cord is between the presenting fetal part & internal-os; has intact membranes

94
Q

complications of umbilical cord prolapse include:

A
  • cord compression or laceration
  • compromised fetal circulation
95
Q

other names for 2 vessel cord?

A

single umbilical artery (SUA) & bivascular cord

96
Q

causes of SUA?

A

agenesis or atrophy of 1 umbilical artery

97
Q

fetal demise after 20 weeks is considered a ____

A

stillbirth

98
Q

fetal demise before 20 weeks is considered an ____

99
Q

what is the main cause of fetal demise in the 1st tri?

A

chromosomal abnormalities

100
Q

the following are ultrasound dx of fetal death in which trimester?
- gas in fetal vasculature
- fetal maceration
- spalding’s sign
- abnormal spine angle
- scalp edema

A

3rd trimester

101
Q

what is spalding’s sign?

A

overlapping cranial sutures – occurs with fetal demise in the 3rd trimester

DMS 400 OB/GYN (21 decks)

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