Chapter 56: Placenta (Powerpoint)

what is the major role of the placenta?

exchange nutrients and oxygenated blood

reaction over the blastocyst closest to the endometrial cavity; capsule for the pregnancy

decidua capsularis

creates the “homebase” for chorionic villi to settle

decidual reaction

fetal part of the placenta

chorion frondosum

maternal part of the placenta

basal plate

arcuate arteries → radial arteries → ____

spiral arteries

functions of the placenta include…

respiration, nutrition, excretion, protection, storage, hormonal production

the placenta functions as a hormonal production site for what hormones?

hCG, estrogen, progesterone

what is normal attachment of the cord?

mid placenta

what are the 2 types of abnormal cord insertions?

marginal and velamentous

in cases of marginal cord insertion, there is concern for…

placenta abruption, placenta previa, SGA

marginal cord insertion is usually seen in what type of twins?

monochorionic

marginal cord insertion is also called a "______.”

battledore placenta

cord insertion that inserts at or less than 2 cm from the edge of placenta

marginal cord insert

abnormal cord insertion where the cord inserts into the fetal membranes, not the placenta and will course around to eventually drop into the placenta

velamentous cord insertion

in cases of velamentous cord, the vessels are not protected by ___.

Wharton’s jelly

velamentous cord is more likely in what type of twins?

mono/mono

in cases of velamentous cord insert, there is an increased risk for…

placental abruption, SGA/IUGR, perinatal death

in cases of velamentous cord insert, a higher risk of placental abruption, SGA/IUGR, and perinatal death occur in those with/associated with ____.

placenta previa, vasa previa

expansion of amniotic cavity occurs with ___.

production of amniotic fluid

at _____ of gestation, amnion fuses with chorion.

16

if the amnion/chorion separation extends beyond 16 weeks of gestation, it may be associated with…

polyhydramnios, aneuploidy, prior amniocentesis/CVS, hemorrhage

a bleed between the amnion and chorion

subchorionic hemorrhage

the umbilical cord forms during the ____ of gestation.

first 5 weeks

what is the umbilical cord surrounded by?

Wharton’s jelly

Wharton’s jelly is composed of ____.

mucoid connective tissue

the intestines grow at a ___ rate than the abdomen.

faster

because the intestines grow at a faster rate than the abdomen, it will herniate into the proximal umbilical cord at ____ and remain there until ___.

7 weeks-10 weeks

___ is an important sonographic anatomic landmark because scrutiny of the area can reveal abdominal wall defects.

insertion of the umbilical cord into ventral abdominal wall

insertion of the umbilical cord into ventral abdominal wall is an important sonographic anatomic landmark because scrutiny of the area can reveal abdominal wall defects such as…

omphalocele, gastroschisis, limb-body wall complex

a 3-vessel cord contains…

2 arteries, 1 vein

a 2-vessel cord cord contains…

1 artery, 1 vein

what are the 3 fetal pathways?

ductus arteriosus, ductus venosus, foramen ovale

the ductus venosus turns into the ____ after birth.

ligamentum venosum

the ligament venosum is located between which lobes of the liver?

left lobe and caudate lobe

the ductus venosus is a branch off of the ___.

umbilical vein

normal sonographic appearance of the placenta

homogenous, smooth borders, mid-level gray echoes

uterine wall blood flow is normal to see, however, creeping in of vessels raises concern for ___.

placental invasion

the placenta can be identified with sonography as early as ____.

8 menstrual weeks

when might placental lakes and calcifications begin to appear?

after 20 weeks’ gestation

the rate at how fast placental calcifications appear corresponds to…

how fast the placenta is aging

thickness of the placenta varies with ____.

gestational age

thickness of the placenta varies with gestational age, but is usually ____ in fetuses >23 weeks.

2-3 cm

normal placenta rarely exceeds a measurement of ___.

4 cm

thickened placenta

placentomegaly

a thickened placenta (placentomegaly) corresponds with…

maternal diabetes, fetal hydrops, Beckwith-Wiedemann syndrome

a very small/thin placenta is associated with…

IUGR, intrauterine infection, chromosomal abnormality/aneuploidy

how does an enlarged/thickened placenta appear on ultrasound?

heterogeneous, greater than 4 cm

enlarged placenta is associated with…

maternal anemia, maternal thalassemia, Rh sensitivity

placental sonolucencies are referred to as ___.

placental lakes

real-time sonography of a placental lake shows…

slow swirling flow

if Color doppler is used on a placental lake, it will show…

no blood flow

if placental cord insertion is marginal or velamentous, what needs to be ruled out?

previa, specifically vasa previa

the inferior edge of the placenta needs to be evaluated to determine its relationship to…

the internal cervical os

abnormal placental positions include…

low-lying or a previa

previa where the placenta is very close to the internal os, within 2 cm

marginal previa

previa where a piece of the placenta is over the internal os

partial previa

previa where the placenta is completely covering the internal os

complete previa

term used to describe the movement of the placenta with the uterus as the uterus grows

placental migration

if there is a previa of any type, the placenta will/will not move with the growth of the uterus.

will not

if the maternal bladder is full, what may happen to the cervix?

could appear falsely elongated

emptying the maternal bladder allows for…

relaxation of the LUS and the normal position of the cervix

what are the multiple factors that are associated with placenta previa?

AMA, smoking, cocaine abuse, prior placenta previa, multiparity, prior c-section, uterine surgery

fetal cord/vessels crossing the internal os is termed _____.

vasa previa

velamentous cord insertion, look for ___.

vasa previa

if anterior and posterior placenta does not appear to communicate, what should be considered?

succenturiate placenta

___ is when additional placental lobes are joined to the main placenta by blood vessels.

succenturiate (accessory lobe) placenta

how do succenturiate lobes normally appear on ultrasound?

usually much smaller, otherwise the same appearance as the placenta, does not contain PCI

what are complications of placenta previa?

preterm delivery, maternal hemorrhage, increased risk of placental invasion, increased risk of postpartum hemorrhage, IUGR

patients with placenta previa may clinically present with…

painless, bright red vaginal bleeding in the 3rd trimester

25% of patients with placenta previa will present with bleeding during the ____.

first 30 weeks

abnormal lie is also associated with ___.

placenta previa

if the placenta has not “moved or migrated” by ___, the patient is at risk for c-section.

32 weeks

what are the most common causes of vasa previa?

velamentous insertion or a succenturiate lobe is present

what is prone to happen when delivery is imminent in cases of vasa previa?

unsupported fetal vessels prone to tear as cervix dilates

abnormal penetration of placental tissue beyond the endometrial lining of the uterus

placental invasion

chorionic villi attach to myometrium without muscular invasion

placenta accreta

placenta accreta occurs in approximately ___ deliveries.

1 in 2500

what types of placenta should make you think placental invasion?

low-lying or anterior placenta in the LUS

type of placenta invasion where the invasion of the chorionic villi is superficial into the myometrium and there is mild blood loss

placenta accreta

type of placental invasion where the invasion of the chorionic villi is deep into the myometrium and there is moderate blood loss

placenta increta

type of placental invasion where the invasion of the chorionic villi passes through the myometrium and usually attacks the posterior bladder wall and there is severe blood loss

placenta percreta

placenta increta results from…

underdeveloped decidualization of endometrium

the association of placenta previa reflects the thin, poorly formed deciduas of the LUS that offers little resistance to deeper invasion by the ___.

trophoblast

____ permits trophoblastic invasion.

previous cesarean scar

high maternal mortality and morbidity is associated with which types of placental invasion?

placenta increta and percreta

attachment of placental membranes to fetal surface of placenta rather than to underlying villous placental margin

circumvallate/circummarginate placenta

what does a circumvallate placenta result in?

placental villi around the border of the placenta not covered by the chorionic plate

circumvallate placenta is diagnosed when…

placental margin is folded, thickened, or elevated with underlying fibrin and hemorrhage

circumvallate placenta is associated with…

PROM, preterm labor, IUGR, and placental abruption

where might placental hemorrhage occur?

within or around placenta

placental hemorrhage is more commonly seen than ___.

placental abruption

refers to bleeding from the placenta from any cause

placental hemorrhage

locations for a placental hemorrhage include..

retroplacental, subchorionic, subamniotic, and intraplacental

the echogenicity depends on the ____ of the hemorrhage.

age

if there is an acute bleed from the placenta, how does it appear?

similar echogenicity of the placenta

subacute and chronic bleeds become more ___.

hypoechoic

a retroplacental abruption results from…

rupture of spiral arteries

a retroplacental abruption is a ___ bleed.

high-pressire

retroplacental abruption is associated with…

HTN and vascular disease