Abnormalities of the Placenta and Cord Flashcards
Low-lying placenta is considered when the inferior margin is how far away from the os?
Within 2cm
Increased placental thickness can be caused by?
- Maternal diabetes
- Immune hydrops
- Placental abruption
Decreased thickness of the placenta can be caused by?
- Maternal hypertension
- Preeclampsia
- IUGR
What can simulate placental thickening?
- Myometrial contractions
- Fibroids
What is the term for selective loss of parts of the placenta and growth of other parts?
Trophoblastic trophotropism
What is the term for a bilobed placenta?
Succenturiate
What is the term for a placenta where the fetal membrane insertion is flat?
Circummarginate
What kind of placenta has a rolled edge?
Circumvallate
Are succenturiate lobes clinically significant? Why or why not?
Yes, because they can cause postpartum hemorrhage and infection
When can placental shelves be detected on ultrasound?
Early second trimester
Risk factors for placenta previa?(4)
- Advanced maternal age
- Previous c-section
- Multiple gestations
- Cocaine or smoking
Why is it important that the bladder isn’t too full when evaluating the placenta?
If the bladder is too distended, it can squish the placenta and make it look as if it is closer to the os than it really is
What does MAP stand for?
Morbidly adherent placenta
MAP encompasses what three types?
- Accreta
- Increta
- Percreta - the most severe
Why has placenta accreta risen 10 fold in the past 50 years?
Due to increased rates of c-sections
What is the most common reason for an emergency postpartum hysterectomy?
Placenta accreta
When is delivery planned in cases of MAP?
34-35 weeks
What are the two most common risk factors for placenta accreta?
- Placenta previa
- Previous c-section
The loss of visualization of what structure indicates a MAP?
Retroplacental complex
When there is multiple vascular lacune present within the placenta, what may this be caused by and in what trimester?
Placenta accreta and in the third trimester
Do venous lakes within the placenta increase or decrease with GA?
Increase
Irregular anechoic structures within the placenta and found beneath the chorionic plate signify what?
Venous lakes
What causes subamniotic cysts?
Rupture of fetal vessels near umbilical cord insertion into the placenta
What are the two primary nontrophoblastic tumors of the placenta?
- Chorioangioma
- Teratoma
T or F? Small solitary chorioangiomas are of little clinical significance
True
If there is a chorioangioma seen with vascular flow and measures 4cm, is it clinically significant?
No, it is reported that it may cause complications when >5 cm
What is the term for the premature separation of all or part of the placenta from the myometrium?
Placental abruption
What are the three types of placental abruption?
- Marginal
- Partial
- Complete
Risk factors of placental abruption?(3)
- Maternal cocaine use and smoking
- Hypertension
- PROM
What abnormality is thought to be cause by the rupture of the chorion without rupture of the amnion?
ABS
What does PMD stand for?
Placental Mesenchymal Dysplasia
What abnormality may be mistaken for a molar pregnancy and appears as “grape-like” vesicles in the placenta?
PMD
What side is most common to see SUA?
Left
What trisomies can be seen with SUA?
13 and 18
In a persistent RUV, the umbilical vein curves toward what rather than toward what?
L-sided stomach rather than the liver
In what abnormality does the umbilical vein curve toward the left sided stomach rather than the liver?
Persistent RUV
Body stalk anomaly vs. limb-body wall complex
Body stalk = NO umbilical cord
Limb-body wall = short umbilical cord
What is body stalk anomaly associated with? (hint: cause)
Maternal cocaine use
What length is a short umbilical cord defined as?
35cm or less
In cases of vasa previa, when is hospitalization recommended?
32 weeks onward
T or F? Bleeding from vasa previa is from maternal origin
False: it is from fetal origin
In cases of umbilical cord cysts, the fetus is more likely to be abnormal when?
The cyst is located near the placenta of fetal extremity or if the cyst persists over 12 weeks GA
Where are TRUE umbilical cord cysts located?
Near the cord insertion into the fetal abdomen
T or F? True umbilical cysts have no increased risk of chromosomal anomalies
True
What can Edematous whartons jelly be confused with?
Teratoma
Imaging an umbilical cord that appears to contain a large mass with cystic areas, solid components, and calcifications indicates what pathology?
Edematous Whartons Jelly
A nuchal cord is describes as what?
The umbilical cord wrapped around the fetal neck one or more times
When does a true umbilical cord knot occur?
When the fetus passes through a loop of cord
Fetuses with true knots are at fourfold risk of what?
Stillbirth
Cord entanglement is a complication in what kind of pregnancies?
Monoamniotic
What abnormality typically occurs in long umbilical cords, hypercoiled cords, and highly active fetuses?
Cord stricture
T or F? Umbilical artery doppler is always assessed
False: It is only assessed when clinically indicated
When should umbilical artery doppler NOT be done?
In low risk pregnancies
In umbilical artery doppler, how many measurements should be taken and what is reported?
At least 3 S/D ratios should be taken and the LOWEST one should be reported
T or F? When performing cord doppler, the waveform should always be monophasic in a healthy fetus
TRUE - waveform doesn’t dip below the baseline
A placenta is considered abnormal when it measures what?
> 4cm before 24 weeks
If the placenta measures 5cm at 30 weeks, is this normal or abnormal?
Normal. It is abnormal if pregnancy is less than 24 weeks
If the placenta measures 5cm at 30 weeks, it this normal or abnormal?
Normal. It is abnormal if pregnancy is less than 24 weeks
With a morbidly adherent placenta, what does the placental tissue invade?
The decidua basalis and myometrium (accreta) and uterine wall (percreta)
Patient presents with acute abdominal and pelvic pain and vaginal bleeding. On ultrasound you visualize a non-vascular subchorionic hematoma. What is the likely diagnosis?
Placental abruption - will NOT be vascular
What 2 trisomies are most commonly associated with a SUA?
Trisomy 13 (P) and trisomy 18 (E)