Module 16: Placental Pathology Flashcards
Define a grade 0 placenta:
Homogenous, chorionic plate is straight
Define a grade 1 placenta:
Scattered echogenic areas, subtle undulations
Define a grade 2 placenta:
Indentations, linear echogenic areas:
Define a grade 3 placenta:
Indentations to basal layer, cystic areas, shadowing calcifications (after 36 weeks)
What would constitute placentomegaly?
≥4 cm thick
What would constitute as a thin placenta?
<1.5 cm
Thickness of the placenta depends on what?
Gestational age
What is the etiology of a thin placenta? (2)
- Vascular deficienciency/infarct
- Pre-eclampsia
What is a maternal lake?
Subchorionic fibrin deposition
What is a placental lake?
Perivillus fibrin deposition
What are placental infarcts?
Microscopic triangular shaped lesions on maternal side of placenta due to obstruction of maternal blood flow
What can make a placenta look low?
Distended bladders
A cervical length is usually what?
3-4 cm
What is placental previa?
Low lying placenta
Describe placenta previa with increasing severity:
- Low lying
- Marginal/Partial
- Complete (as uterus moves up, placenta is tearing - very serious)
What is the clinical history for placenta previa?
Painless vaginal bleeding
What may painful vaginal bleeding indicate?
Abruption
What is the gold standard for investigating a low lying placenta?
EV
What constitutes a low lying placenta?
When placenta is <2 cm from the internal os but not overlying it
Describe partial vs complete placental previa:
Partial: placenta touches the internal os
Complete: Placenta completely covers the internal os
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?
24-28 weeks
And then every two weeks until placenta is seen migrating
Why is color Doppler performed with EV at the cervix during the 24-28 week visit?
To see if there are vessels crossing the exit of the cervix
Describe the variations in shape of a placenta: (3)
- Succenturiate
- Extrachorial
- Membranacea
What are the two branches of extrachorial placenta?
Cicummarginate and circumvallate
What is a succenturiate?
Accessory lobe of the placenta that is connected via vessels within the membrane
What is seen with an extrachorial placenta?
Chorionic plate does not extend to edge of placenta and membrane extends over placenta
What is seen with a circummarginate extrachorial placenta?
Flat ring at attachment to chorionic plate
What is seen with a circumvallate extrachorial placenta?
Fold in the membrane at site of attachment
What may an extrachorial placenta cause at delivery?
Antepartum hemorrhage
What do you want to ensure with a synechiae (uterine scar)?
That the fetus is not attached to it, otherwise this would indicate amniotic band syndrome
What is placenta membranacea?
Entire uterine surface is covered with placenta
What is a battledore cord insertion?
Marginal cord insertion <3 cm from placental edge
What is a velamentous cord insertion?
Cord inserting into the chorionic membranes and then vessels track to placenta
What is vasa previa?
Fetal vessels across internal os
What is placental abruption?
When placenta tears from uterine wall
Where may placental hemorrhage occur?
Marginal, retroplacental
What are the 3 different formations of placental abruption? (3)
- External bleeding, no hematoma
- Retroplacental hematoma without external bleeding
- Subchorionic hematoma with or without bleeding
What are symptoms of placental abruptions? (4)
- Preterm labor contractions
- Bleeding
- Pain
- Fetal distress
What is a teratoma?
Rare germ cell tumor of the placenta
What is a chorioangioma of a placenta?
Vascular tumor that is a well defined complex mass that may cause hydrops heart failure.
Define placenta accreta:
When the placenta attaches to the myometrium instead of the basalis
Define placenta increta:
The placenta invades INTO myometrium
Define placenta percreta:
Placenta invades through to perimetrium and even beyond
What are the most common risks that occur with placenta accreta (In or Per)?
- Post-partum bleeding due to difficult removal
- Hysterectomy post delivery
- DIC (disseminated intravascular coagulation - clotting throughout body)
What conditions cause placentomegaly? (7)
- Maternal diabetes
- Maternal Anemia
- Hydrops
- Placental hemorrhage
- Intrauterine infection
- Partial mole
- Chromosomal abnormalities
What is vasoprevia?
Vessels connecting placenta with succenturiate lobe travelling across cervix
What is accreta associated with? (9)
- Placenta previa *
- Only anterior placentas *
- C-section *
- Maternal age
- Uterine abnormalities
- Smoking
- Myomectomy
- Prev. Uterine surgery
- Previous D&C
What vessels does the umbilical cord normally have?
2 umb arteries and 1 vein
