Chapter 55 power point Placenta

Question 1

Chorion frondosum
Chorion laeve
Chorionic plate
Basal plate

Answer 1

Embryogenesis

Question 2

Forms fetal part of placenta; contains villi

Answer 2

Chorion frondosum

Question 3

Nonvillious part of chorion around gestational sac

Answer 3

Chorion laeve

Question 4

Fetal surface of placenta

Answer 4

Chorionic plate

Question 5

Maternal surface of placenta

Answer 5

Basal plate

Question 6

Respiration
Nutrition
Excretion
Protection
Storage
Hormonal Production

Answer 6

Function of the Placenta

Question 7

Fetal blood continues inferiorly to return to placenta for respiratory and nutrient exchange

By term approximately 40% of fetal cardiac output is directed through umbilical circulation

Answer 7

Fetal-Placental-Uterine Circulation

Question 8

Attachment of cord is usually near center of placenta

Abnormal cordal attachments to placenta are battledore and velamentous placenta

Answer 8

Cordal Attachments

Question 9

Chorion
Amnion
Allantois
Yolk sac

Answer 9

Fetal membranes

Question 10

Permitting fetus room to move
Assisting maintaining constant fetal body temperature
Serving as protective buffer for fetus
Allowing lungs to develop properly

Answer 10

AF functions

Question 11

Forms during first 5 weeks of gestation
Is surrounded by mucoid connective tissue called Wharton’s jelly
Normal umbilical cord has one large vein and two smaller arteries

Answer 11

The Umbilical Cord

Question 12

found in approximately 1% of all singleton births and 7% of twin gestations

Congenital malformations seen in 25% to 50% of infants with SUA

Answer 12

Single umbilical artery

Question 13

Abnormal trophoblastic invasion of spiral arteries of maternal uteroplacental circulation associated with:
Placental insufficiency 
IUGR 
Preeclampsia 
Placental abruption

Answer 13

Doppler Evaluation of the Placenta

Question 14

Normal term placenta has several characteristics 
Measures about 15 to 20 cm in diameter
Discoid in shape 
Weighs about 600 g 
Measures <4 cm in thickness

Answer 14

Evaluation of the Placenta After Delivery

Question 15

> 5 cm thick edge to edge

Answer 15

Placentomeglay

Question 16

Intrauterine growth restriction
Intrauterine infection
Aneuploidy

Answer 16

Small Placenta

Question 17

Implantation of placenta over internal cervical os

Normally implants in body or fundus of uterus

In one of 200 pregnancies placenta implants over or near to internal os of cervix

Risk increases with history of cesarean delivery

Answer 17

Placenta Previa

Question 18

Advanced maternal age
Smoking 
Cocaine abuse 
Prior placental previa 
Multiparity 
Prior cesarean section 
Uterine surgery

Answer 18

factors associated with placenta previa

Question 19

Preterm delivery 
Maternal hemorrhage 
Increased risk of placental invasion 
Increased risk of postpartum hemorrhage 
IUGR

Answer 19

Complications of placenta previa

Question 20

may present with painless, bright red vaginal bleeding in third trimester

25% of patients will present with bleeding during first 30 weeks

20% of cases associated with uterine focal myometrial contractions

Abnormal lie also associated with placenta previa

Answer 20

Clinical placenta previa

Question 21

Abnormal penetration of placental tissue beyond endometrial lining of uterus

Variants of placenta invasion exist

Answer 21

Placental Invasion

Question 22

Chorionic villi attach to myometrium without muscular invasion

Placenta accreta occurs in approximately 1 in 2500 deliveries

Answer 22

Placenta accreta

Question 23

penetration of the chorionic villi through the uterus

Answer 23

Placenta percreta

Question 24

the chorionic placve of the placenta is smaller than the basal plate, with a flas interface between the fetal membrane and the placenta

Answer 24

Circummarginate Placenta

Question 25

condition where the chorionic plate is smaller than the basal plate, the margin is raised with a rolled edge

Answer 25

Circumvallate Placenta

Question 26

May occur within or around placenta

Is more commonly seen than placental abruption

Locations include retroplacental, subchorionic, subamniotic, and intraplacental sites

Answer 26

Placental Hemorrhage

Question 27

Echogenicity depends on age of the hemorrhage.

Acute bleed similar to echogenicity of placenta

Subacute and chronic bleed becomes more hypoechoic.

Bleed may be retroplacental or subchorionic.

Answer 27

Placental Hemorrhage sonographically

Question 28

Results from rupture of spiral arteries and is “high-pressure” bleed

Is associated with HTN and vascular disease

Hematoma is between placenta and uterus

If blood remains retroplacental, patient may have no vaginal bleeding

Answer 28

Retroplacental Abruption

Question 29

Most common type of abruption

Known as subchorionic bleeds

Hemorrhage results from tears of the marginal veins and represents “low-pressure” bleed.

Arises from edge of placenta, dissects beneath placental membranes and is associated with little placental detachment

Answer 29

Marginal Abruption

Question 30

Focal discrete lesion caused by ischemic necrosis

Is found in 25% of pregnancies, usually small with no clinical significance

Large infarcts may reflect underlying maternal vascular disease.

Answer 30

Placenta Infarcts

Question 31

Benign vascular tumor of placenta

Most common “tumor” of placenta

Usually small

Consists of benign proliferation of fetal vessels; majority are capillary hemangiomas that arise beneath chorionic plate

Answer 31

Chorioangioma

Question 32

Di/di: pregnancy probably dizygotic (97% chance)

Diamniotic/dichorionic/two placentas can occur in monozygotic pregnancies when division occurs during first 4 days of gestation

Mono/di or mono/mono: from monozygotic pregnancy

Answer 32

Placenta in Multiple Gestation

Question 33

Derived from two zygotes
Diamniotic/dichorionic/two placentas
Occurs during first 4 days of gestation

Answer 33

Dizygotic (fraternal twins)

Question 34

Derived from one zygote
Diamniotic/dichorionic/two placentas
Monochorionic/diamniotic/one placenta
Occurs during first week of gestation
Monochorionic/monoamniotic/one placenta
Occurs during second week of gestation

Answer 34

Monozygotic (identical twins)