Class 14: Placenta Flashcards
1
Q
shape of placenta
A
disc shaped
2
Q
size of placenta at term
A
500-600g
3
Q
2 compartments of the placenta?
A
- fetal side
- maternal side
4
Q
where is the fetal side of the placenta?
A
choroid/chorionic plate with chorionic villi at the site of implantation
5
Q
where is the maternal side of the placenta?
A
side of decidua basilis with cotyledons
6
Q
function of the placenta?
A
- works as fetal lungs
- exchanges blood and nutrients bw mother & fetus
7
Q
what is the functioning unit of the placenta?
A
chorionic villi
8
Q
4 locations a placenta can be in the uterus
A
- anterior
- posterior
- lateral
- fundal
9
Q
how thick can a normal placenta be?
A
1.5-5cm
10
Q
what can a placenta less than 1.5 cm indicate?
A
IUGR or preeclampsia
11
Q
what can a placenta over 5 cm inidicate?
A
maternal diabetes or fetal hydrops
12
Q
what trimester can venous lakes be seen in?
A
2nd or 3rd
13
Q
what are venous lakes?
A
intraplacental & subchorionic anechoic spaces
14
Q
where is the retroplacental complex?
A
behind the placenta
15
Q
what does the retroplacental complex consist of?
A
decidua basilis, some myometrium, maternal vasculature
16
Q
U/S appearance of retroplacental complex
A
horizontal echoes
17
Q
3 types of cord insertion into the placenta
A
- central
- battledore
- velamentous/membranous
18
Q
where does a central cord insertion attach to?
A
near the center of the placenta
19
Q
where does a battledore cord insertion attach to?
A
towards the edge of the placenta
20
Q
where does a velamentous/membranous cord insertion attach to?
A
cord inserts into membranes before entering the placenta
21
Q
what is a velamentous cord insertion associated with?
A
IUGR/FGR due to placenta insufficiency
22
Q
___% of placentas have calcification after ___ weeks
A
50%; 33 weeks
23
Q
U/S appearance of placental calcification?
A
hyperechoic foci without shadowing
24
Q
what placental grades are normal until term?
A
grade 1,2,3
25
what grade is this placenta?
smooth chorionic plate, homogenous placenta, no calcification
grade 0
26
it is abnormal to see grade 0 placenta after ___ weeks
30 weeks
27
what does a grade 0 placenta after 30 weeks indicate?
maternal diabetes or fetal hydrops
28
what grade is this placenta?
chorionic plate starts forming indentations, placenta is developing echogenic foci
grade 1
29
what weeks does a grade 1 placenta start developing?
~ 31-36 weeks
30
what grade is this placenta?
chorionic plate develops more folds and the basal plate now has calcifications
grade 2
31
what weeks does a grade 2 placenta start developing?
~ 36-38 weeks
32
what grade is this placenta?
complete indentation of chorionic plate, basal calcifications now have interlobar septal calcifications, and venous lakes in intervillous spaces
grade 3
33
grade 3 before ___ weeks can indicate IUGR/FGR or maternal preeclampsia
35 weeks
34
what size is considered placentamegaly?
> 5 cm
35
most common cause of placentamegaly?
maternal diabetes
36
what is beckwith-wiedman syndrome?
congenital overgrowth syndrome
37
what size placenta is associated with beckwith-wiedman syndrome
placentamegaly
38
what size is considered placental insufficiency?
< 1.5 cm
39
4 abnormal placenta shapes?
1. bilobed/bipartite
2. succenturiate lobe
3. annular placenta
4. placenta membranacia/diffusa
40
what is a bilobed placenta?
placenta with 1 anterior lobe & 1 posterior lobe
41
what is a succenturiate placenta?
placenta with an accessory placenta
42
risk of having a succenturiate placenta?
post partum hemorrhage if accessory placenta is undelivered
43
what is an annular placenta?
a ring-shaped placenta
44
what placental abnormality is associated with an annular placenta?
placenta previa
45
what is a placenta membranacea/diffusa?
a placenta develops as a thing membranous structure with chorionic villi stretching all around
46
what is placenta previa?
an abnormal placenta that partially or completely covers the internal-os
47
what is the most common cause of painLESS bleeding in the 3rd trimester?
placenta previa
48
4 types of placenta previa?
complete, partial, marginal, low-lying
49
what is complete placenta previa?
placenta covers entire internal-os & is attached on both sides of UT
50
what is partial placenta previa?
placenta partially covers internal-os
51
what is marginal placenta previa?
placenta's edges touch the margins of internal-os
52
what is a low-lying placenta?
placenta that is in the lower uterine segment
53
how close does a placenta have to be from internal-os to be considered low lying?
2 cm away from internal-os
54
what weeks does diagnosing placenta previa usually occur in?
34-36 weeks unless over 1/3 covers the internal-os
55
why does diagnosis of placenta previa not occur until later in pregnancy?
placental migration
56
the following are risk factors for what placental abnormality?
advanced maternal age, previous c-section, multiple gestations, cocaine use, smoking, multiparity, and uterine scarring
placenta previa
57
what are 3 complications of placenta previa?
post partum hemorrhage
preterm labor
bleeding
58
what type of imaging is most commonly used with placenta previa?
transvaginal
59
what is placental abruption?
the premature separation of all or part of placenta from myometrium
60
why is placental abruption a medical emergency?
it can cause catastrophic hemorrhage
61
what is the most common painful bleeding in the 3rd trimester?
placental abruption
62
the following may cause what placental abnormality?
advanced maternal age, trauma, short umbilical cord, maternal HTN, maternal vascular disease
placental abruption
63
2 types of placental abruption
1. marginal
2. retroplacental
64
what causes marginal placental abruption? is it low or high pressure bleeding?
tears of marginal veins cause low pressure bleeding
65
marginal placental abruption is associated with vascular disease and hypertension. T/F?
false -- it is associated with cigarette smoking
66
what causes retroplacental abruption and what type of bleeding can it cause?
spiral arteries rupture and can cause high pressure bleeding
67
there is visible bleeding with retroplacental abruption. T/F?
false -- no visible bleeding
68
what maternal conditions are associated with retroplacental abruption?
HTN & vascular disease
69
what is placental attachment disorder?
placenta attaches abnormally to uterine wall due to defect in decidua basilis
70
3 types of placental attachment disorders?
1. placenta accreta
2. placenta increta
3. placenta percreta
71
what is placenta accreta?
PAD where chorionic villi is in direct contact with myometrium
72
what is placenta increta?
PAD where chorionic villi infiltrate myometrium
73
what is placenta percreta?
PAD where chorionic villi infiltrate perimetrium & possibly other organs
74
what may be the cause of PAD?
uterine scarring
75
what other placental abnormality is present with PAD?
placenta previa
76
what is the preferred imaging modality for PAD?
MRI
77
2 placental tumors?
1. chorioangioma
2. teratoma
78
what is the most common benign placental tumor?
chorioangioma
79
what is a chorioangioma?
a vascular malformation of the placenta
80
complications of chorioangioma?
IUGR
fetal hydrops
fetal demise
premature labor
81
teratomas of the placenta are rare. T/F?
true
82
U/S appearance of teratoma?
complex appearance
83
what is the umbilical cord composed of?
1 vein & 2 spiral arteries surrounded by wharton's jelly, which is enclosed by a layer of amnion
84
when is the umbilical cord best seen?
2nd and 3rd trimesters
85
what is the normal length of the umbilical cord at term?
about 55 cm; ranges 30-120 cm
86
U/S appearance of the umbilical cord in TRV?
TRV: mickey mouse sign
87
what is a nuchal cord?
an umbilical cord that is looped at least once around fetus' neck
88
complications of nuchal cord?
usually clinically insignificant, but can cause:
decrease fetal breathing, movement, and birth weight
meconium staining
89
what can meconium staining cause?
respiratory problems for the fetus
90
3 types of umbilical cord prolapse?
1. occult/hidden
2. frank
3. vasa previa
91
what is an occult/hidden umbilical cord prolapse?
the cord is near presenting fetal part
92
what is a frank prolapse of the umbilical cord?
the cord protrudes into the cervix and has ruptured membranes
93
what is a vasa previa prolapse of the umbilical cord?
the cord is between the presenting fetal part & internal-os; has intact membranes
94
complications of umbilical cord prolapse include:
- cord compression or laceration
- compromised fetal circulation
95
other names for 2 vessel cord?
single umbilical artery (SUA) & bivascular cord
96
causes of SUA?
agenesis or atrophy of 1 umbilical artery
97
fetal demise after 20 weeks is considered a ____
stillbirth
98
fetal demise before 20 weeks is considered an ____
abortus
99
what is the main cause of fetal demise in the 1st tri?
chromosomal abnormalities
100
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
3rd trimester
101
what is spalding's sign?
overlapping cranial sutures -- occurs with fetal demise in the 3rd trimester
