Module 16: Placental Pathology

Question 1

Define a grade 0 placenta:

Answer 1

Homogenous, chorionic plate is straight

Question 2

Define a grade 1 placenta:

Answer 2

Scattered echogenic areas, subtle undulations

Question 3

Define a grade 2 placenta:

Answer 3

Indentations, linear echogenic areas:

Question 4

Define a grade 3 placenta:

Answer 4

Indentations to basal layer, cystic areas, shadowing calcifications (after 36 weeks)

Question 5

What would constitute placentomegaly?

Answer 5

≥4 cm thick

Question 6

What would constitute as a thin placenta?

Answer 6

<1.5 cm

Question 7

Thickness of the placenta depends on what?

Answer 7

Gestational age

Question 8

What is the etiology of a thin placenta? (2)

Answer 8

• Vascular deficienciency/infarct

- Pre-eclampsia

Question 9

What is a maternal lake?

Answer 9

Subchorionic fibrin deposition

Question 10

What is a placental lake?

Answer 10

Perivillus fibrin deposition

Question 11

What are placental infarcts?

Answer 11

Microscopic triangular shaped lesions on maternal side of placenta due to obstruction of maternal blood flow

Question 12

What can make a placenta look low?

Answer 12

Distended bladders

Question 13

A cervical length is usually what?

Answer 13

3-4 cm

Question 14

What is placental previa?

Answer 14

Low lying placenta

Question 15

Describe placenta previa with increasing severity:

Answer 15

1. Low lying
2. Marginal/Partial
3. Complete (as uterus moves up, placenta is tearing - very serious)

Question 16

What is the clinical history for placenta previa?

Answer 16

Painless vaginal bleeding

Question 17

What may painful vaginal bleeding indicate?

Answer 17

Abruption

Question 18

What is the gold standard for investigating a low lying placenta?

Answer 18

EV

Question 19

What constitutes a low lying placenta?

Answer 19

When placenta is <2 cm from the internal os but not overlying it

Question 20

Describe partial vs complete placental previa:

Answer 20

Partial: placenta touches the internal os

Complete: Placenta completely covers the internal os

Question 21

If the placenta is <2 cm from the internal os after a post void bladder assessment at the 18 week scan, when is the patient to return?

Answer 21

24-28 weeks

And then every two weeks until placenta is seen migrating

Question 22

Why is color Doppler performed with EV at the cervix during the 24-28 week visit?

Answer 22

To see if there are vessels crossing the exit of the cervix

Question 23

Describe the variations in shape of a placenta: (3)

Answer 23

1. Succenturiate
2. Extrachorial
3. Membranacea

Question 24

What are the two branches of extrachorial placenta?

Answer 24

Cicummarginate and circumvallate

Question 25

What is a succenturiate?

Answer 25

Accessory lobe of the placenta that is connected via vessels within the membrane

Question 26

What is seen with an extrachorial placenta?

Answer 26

Chorionic plate does not extend to edge of placenta and membrane extends over placenta

Question 27

What is seen with a circummarginate extrachorial placenta?

Answer 27

Flat ring at attachment to chorionic plate

Question 28

What is seen with a circumvallate extrachorial placenta?

Answer 28

Fold in the membrane at site of attachment

Question 29

What may an extrachorial placenta cause at delivery?

Answer 29

Antepartum hemorrhage

Question 30

What do you want to ensure with a synechiae (uterine scar)?

Answer 30

That the fetus is not attached to it, otherwise this would indicate amniotic band syndrome

Question 31

What is placenta membranacea?

Answer 31

Entire uterine surface is covered with placenta

Question 32

What is a battledore cord insertion?

Answer 32

Marginal cord insertion <3 cm from placental edge

Question 33

What is a velamentous cord insertion?

Answer 33

Cord inserting into the chorionic membranes and then vessels track to placenta

Question 34

What is vasa previa?

Answer 34

Fetal vessels across internal os

Question 35

What is placental abruption?

Answer 35

When placenta tears from uterine wall

Question 36

Where may placental hemorrhage occur?

Answer 36

Marginal, retroplacental

Question 37

What are the 3 different formations of placental abruption? (3)

Answer 37

1. External bleeding, no hematoma 2. Retroplacental hematoma without external bleeding 3. Subchorionic hematoma with or without bleeding

Question 38

What are symptoms of placental abruptions? (4)

Answer 38

- Preterm labor contractions - Bleeding - Pain - Fetal distress

Question 39

What is a teratoma?

Answer 39

Rare germ cell tumor of the placenta

Question 40

What is a chorioangioma of a placenta?

Answer 40

Vascular tumor that is a well defined complex mass that may cause hydrops heart failure.

Question 41

Define placenta accreta:

Answer 41

When the placenta attaches to the myometrium instead of the basalis

Question 42

Define placenta increta:

Answer 42

The placenta invades INTO myometrium

Question 43

Define placenta percreta:

Answer 43

Placenta invades through to perimetrium and even beyond

Question 44

What are the most common risks that occur with placenta accreta (In or Per)?

Answer 44

- Post-partum bleeding due to difficult removal - Hysterectomy post delivery - DIC (disseminated intravascular coagulation - clotting throughout body)

Question 45

What conditions cause placentomegaly? (7)

Answer 45

- Maternal diabetes - Maternal Anemia - Hydrops - Placental hemorrhage - Intrauterine infection - Partial mole - Chromosomal abnormalities

Question 46

What is vasoprevia?

Answer 46

Vessels connecting placenta with succenturiate lobe travelling across cervix

Question 47

What is accreta associated with? (9)

Answer 47

- Placenta previa * - Only anterior placentas * - C-section * - Maternal age - Uterine abnormalities - Smoking - Myomectomy - Prev. Uterine surgery - Previous D&C

Question 48

What vessels does the umbilical cord normally have?

Answer 48

2 umb arteries and 1 vein