The Placenta ✔️ Flashcards
what are the septations from decidua grow between creating lobules
cotyledons
what is the fundamental unit of the placenta
chorionic villi
placenta is an __________ gland
endocrine
what are the 6 major roles of the placenta
respiration nutrition excretion protection storage hormonal production
define respiration
exchange maternal oxygenated blood with fetal deoxygenated blood
define nutrition
carries nutrients from mother to baby
define excretion
carries wastes from baby to mother
define protection
protects baby from some microorganisms from mother
define storage
stores carbs, proteins, calcium, iron
define hormonal production
hCG, estrogen, progesterone
what are the parts of the fetal chorion
chorion frondosum
chorion laeve
chorionic plate
basal plate
define chorion frondosum
fetal part of the placenta-chorionic villi
define laeve
nonvillious part of chorion around the GS
define chorionic plate
fetal surface of placenta
- umbilical cord attached to this surface
- formed by amniochorionic membrane
define basal plate
maternal surface of placenta
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
types of placenta position
posterior anterior rt lateral lt lateral fundal combination
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
describe battledore placenta
cord insertion within 10 mm of placental edge - usually no clinical significance
also called marginal
define velamentous placenta
cord insertion on the placental membranes
may be associated with significant fetal hemorrhage
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
BE SURE TO REVIEW POWERPOINT TO SEE IMAGE EXAMPLES
BE SURE TO REVIEW POWERPOINT TO SEE IMAGE EXAMPLES
describe braxton-hicks contractions
may distort uterine contour
should rescan in 15-20 mins
describe placenta previa
PAINLESS bleeding
need to scan LUS to show internal os
types are complete, partial, marginal/low lying
vasa previa
define complete placenta previa
placenta completely covers internal os
define partial placenta previa
on one side of internal os covered by placenta
define marginal or low lying placenta previa
placenta tip within 2 cm of internal os
does not cover any portion of os
define placenta accreta
chorionic villi attach superfically to the myometrium
increase risk with previa and previous c-section
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
define placenta percreta
penetration of chorionic villi through the uterus
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
3 zones of evaluation of placental grading
- basal layer
- placental tissue
- chorionic layer
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
define placenta extrachorialis
chorionic plate is smaller than basal plate
may be associated with bleeding/pre-term labor
circummarginate & circumvallate
describe placenta extrachorialis circummarginate
not detected sonographically
placenta remains flat
describe placenta extrachorialis circmvallate
placenta edge appears folded/curled
describe placenta abruption
premature placenta detachment
vaginal bleeding, pain, fetal distress or demise
marginal or retroplacental
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
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
describe placenta infarction
ischemic necrosis
common
25% of pregnancies
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)
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
placentas with multiple pregnancies:
describe dizygotic (fraternal twins)
diamniotic/dichorionic - 2 placentas
2 sacs - thick membrane
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
