The Placenta ✔️ Flashcards Preview

Fall 2014 - OB II > The Placenta ✔️ > Flashcards

Flashcards in The Placenta ✔️ Deck (44):
0

what is the fundamental unit of the placenta

chorionic villi

1

what are the septations from decidua grow between creating lobules

cotyledons

2

placenta is an __________ gland

endocrine

3

what are the 6 major roles of the placenta

respiration
nutrition
excretion
protection
storage
hormonal production

4

define respiration

exchange maternal oxygenated blood with fetal deoxygenated blood

5

define nutrition

carries nutrients from mother to baby

6

define excretion

carries wastes from baby to mother

7

define protection

protects baby from some microorganisms from mother

8

define storage

stores carbs, proteins, calcium, iron

9

define hormonal production

hCG, estrogen, progesterone

10

what are the parts of the fetal chorion

chorion frondosum
chorion laeve
chorionic plate
basal plate

11

define chorion frondosum

fetal part of the placenta-chorionic villi

12

define laeve

nonvillious part of chorion around the GS

13

define chorionic plate

fetal surface of placenta
-umbilical cord attached to this surface
-formed by amniochorionic membrane

14

define basal plate

maternal surface of placenta

15

describe placenta

indentified as early as 8 wks
normal thickness 2-5 cm
max thickness should nt exceed 5 cm
develops where implantation occurs
grows more rapidly before 20 wks
location described as position on uterine wall

16

types of placenta position

posterior
anterior
rt lateral
lt lateral
fundal
combination

17

describe cord insertion

usually near center of placenta

types of insertions: battledore placenta, velamentous placenta, vasa previa

best to use color doppler to accurately identify placental cord insertion

18

describe battledore placenta

cord insertion within 10 mm of placental edge - usually no clinical significance

also called marginal

19

define velamentous placenta

cord insertion on the placental membranes

may be associated with significant fetal hemorrhage

20

define vasa previa

cord insertion on placental membranes which lie across the internal os

associated with velamentous cord insertion, previa, multiple gestation

symptoms: vagianl bleeding, fetal heart decelerates

21

BE SURE TO REVIEW POWERPOINT TO SEE IMAGE EXAMPLES

BE SURE TO REVIEW POWERPOINT TO SEE IMAGE EXAMPLES

22

describe braxton-hicks contractions

may distort uterine contour

should rescan in 15-20 mins

23

describe placenta previa

PAINLESS bleeding

need to scan LUS to show internal os

types are complete, partial, marginal/low lying

vasa previa

24

define complete placenta previa

placenta completely covers internal os

25

define partial placenta previa

on one side of internal os covered by placenta

26

define marginal or low lying placenta previa

placenta tip within 2 cm of internal os

does not cover any portion of os

27

define placenta accreta

chorionic villi attach superfically to the myometrium

increase risk with previa and previous c-section

28

define placenta increta

further invasion of chorionic villi deep into the myometrium

10-25% risk in women with previous c-section if placenta implants over scar

29

define placenta percreta

penetration of chorionic villi through the uterus

30

define succenturiate placenta

one or more accessory lobes connected to the body of the placenta vessels

3-6% of pregnancies

**MUST visualize velamentous insertion of cord between main and accessory lobe

higher incidence of placental infarction

31

3 zones of evaluation of placental grading

1. basal layer

2. placental tissue

3. chorionic layer

32

describe placenta grading descriptions from grade 0 to grade III

grade 0 - smooth chorionic plate, homogenous echotexture, 8-20 wks, indistinguishable basal plate

grade I - small intraplacental calcifications, 14-34 wks, indistinguishable basal plate

grade II - calcification of basal plate, "dot-dash" pattern along basal plate indentations of chorionic plate, 30+ wks, all 3 zones are affected

grade III - calcified indentation of placenta extending from basal to chorionic plate (cotyledons), 35+ wks, caused from smoking, IUGR, chronic HTN, DM

33

define placenta extrachorialis

chorionic plate is smaller than basal plate

may be associated with bleeding/pre-term labor

circummarginate & circumvallate

34

describe placenta extrachorialis circummarginate

not detected sonographically

placenta remains flat

35

describe placenta extrachorialis circmvallate

placenta edge appears folded/curled

36

describe placenta abruption

premature placenta detachment

vaginal bleeding, pain, fetal distress or demise

marginal or retroplacental

37

describe marginal placenta

MOST COMMON

results from tears of marginal veins

LOW PRESSURE BLEED

associated with cigarette smoking

causes little placental detachment

location - retroplacental or marginal

38

describe retroplacental abruption

results from rupture of spiral arteries

HIGH PRESSURE BLEED

associated with htn, diabetes, previous abruption, drugs, *trauma*, hx of placenta previa

**patients have no visible bleeding

outcome depends on size

acute - hyperechoic / 3-7 days isoechoic / 1-2 wks hypoechoic

39

describe placenta infarction

ischemic necrosis

common

25% of pregnancies

40

describe placenta tumors

MOLAR PREGNANCIES

benign or malignant
complete or partial

clinical symptoms - N&V, vaginal bleeding, higher hCG, uterus large for dates

12-15% develop malignant (choriocarcinoma)

41

describe chorioangioma

benign vascular tumor of the placenta

secondary to trophoblastic disease

MOST COMMON tumor of the placenta

fetal complications - polyhydramnios, anemia, cardiomegaly, IUGR, demise, pre-term labor

42

placentas with multiple pregnancies:

describe dizygotic (fraternal twins)

diamniotic/dichorionic - 2 placentas

2 sacs - thick membrane

43

placentas with multiple pregnancies:

describe monozygotic (identical twins)

diamniotic/dichorionic - 2 placentas (peak sign), 2 sacs - thick membrane

diamniotic/monochorionic - 1 placenta, 2 sacs - thin membrane

monoamniotic/monochorionic - 1 placenta, 1 sac