Multifetal Gestation and Malpresentation (Moulton) Flashcards
(48 cards)
__1__ arise when two separate ova are fertilized by two separate sperm.
Each will have its own __2__, __2__, and __2__.
1) Dizygotic twins (Fraternal)
2) Amnion, chorion and placenta
__1__ arise from the cleavage of a single fertilized ovum at various stages during embryogenesis.
Thus the arrangement of __2__ and __2__ will depend on the time at which the embryo divides.
1) Monozygotic Twinning (Identical)
2) Fetal membranes and placentas
With Monozygotic twins, if cleavage takes place from 0-3 days, what happens with placentation? (30% of monozygotic twins have this placentation)
1) 2 chorions
2) 2 amnions
3) Placentas can be separate or fused
With Monozygotic twins, if cleavage takes place from 4-8 days, what happens with placentation? (69% of monozygotic twins have this placentation)
1) 1 chorion
2) 2 amnions
With Monozygotic twins, if cleavage takes place from 9-12 days, what happens with placentation? (1% of monozygotic twins have this placentation)
1) 1 chorion
2) 1 amnion
Monochorionic monoamniotic placentation (9-12 days) is the most dangerous because there are no separating amnions, this causes what risk to be high?
Risk of Cord entanglement
With Monozygotic twins, if cleavage takes place from 13-15 days, what happens with placentation?
This causes conjoined twins and if they are craniopagus (2% incidence) this means?
If they are thoracopagus (30-40% incidence)?
If they are ischiopagus (6% incidence)?
1) 1 chorion and 1 amnion
2) Joined at the cranium
3) Joined at the chest wall
4) Joined by the coccyx and sacrum
Dizygotic twins is strongly influenced by?
It is twice as common after?
1) Maternal age
2) 35 y/o
You should suspect multiple gestations if ___ is higher than normal.
hCG
Which type of twins have an increased incidence of
- Congenital anomalies
- Weight discordance
- Premature delivery
- Fetal demise?
Monozygotic
Dizygotic Ultrasound
When using US when determining zygosity for dizygotic twins you might see a different __1__ amongst the twins.
2) What septum can be visualized?
3) What sign at the base of septum may be seen?
1) Fetal gender
2) Thick amnion-chorion septum
3) Peak or inverted V
When using US when determining zygosity for monozygotic twins what may be seen?
Dividing membrane is thin
If ultrasound is not definitive in determining zygosity, what should you do?
1) Inspect placenta after delivery
2) DNA analysis
Conjoined twins
1) When does cleavage occurring at?
2) When should elective termination be an option?
3) What type of delivery occurs
1) 13-15 days
2) Cardiac or Cerebral fusion
3) C-Section
1) Who does Interplacental Vascular anastomoses occur in?
2) Which is the most common type is of IVA?
1) Monochorionic twins
2) Arterial-arterial
With interplacental vascular anastomoses, vascular communications between the 2 fetuses through the placenta can cause several problems such as?
1) Polyhydramnios
2) Abortion
3) Twin-twin transfusion syndrome (TTTS)
PAT
Twin-twin transfusion syndrome results secondary to uncompensated __1__ in a monochorionic placenta.
This leads to a net transfer of blood flow going from one twin to the other. Hypovolemia, hypotension, anemia, oligohydramnios, growth restriction occurs to the __2__.
Hypervolemia, polyhydramnios, thrombosis, hypertension, polycythemia, edema, cardiomegaly, and congestive heart failure occurs to the __3__.
1) Arteriovenous anastomoses
2) Donor twin
3) Recipient twin
With Twin-twin transfusion syndrome both twins are at risk of demise because of?
Heart failure
What findings on US for TTTS are seen with the donor twin?
For the recipient twin?
1) Smaller, stuck appearance, oligohydramnios
2) Larger, polyhydramnios, ascites
*Larger from more fluid
TTTS treatment consists of ____ of the anastomosis vessels on the placenta at specialized centers.
Laser photocoagulation
*Find Anastomoses
Ablation with laser zip zip
ARTERIAL TO ARTERIAL ANASTOMOSES (monozygotic malformation)
Arterial to arterial anastomoses may lead to reversed blood flow causing __1__ within critical organs or
atresias due to trophoblastic embolization.
The recipient twin, being perfused in a reverse direction with poorly oxygenated blood fails to develop normally. It is known as an __2__ twin.
This twin presents with fully formed __3__ but no anatomic structures above the __4__.
1) Thrombosis
2) Acardiac twin
3) Lower extremities
4) Abdomen
*Uterine vein brings o2 rich blood into Donor bably
Blood leaves from donor through Uterine artery.
Recepient has o2 rich blood coming in through uterine artery AND waste blood out through Uterine Artery
THe two arteries attach and Recipient has blood from both directions then becoming reversed.
What umbilical cord abnormalities can be seen primarily with monochorionic twins?
1) Absence of umbilical artery
2) Velamentous umbilical cord insertions (umbilical cord in wrong position)
1) What is it called if one of monozygotic fetus dies at or past 20 weeks gestation
If gestation is < 12 weeks the dead fetus is __2__ and is known as what?
If > 12 weeks, the fetus shrinks, dehydrates and flattens called __3__.
1) Retained dead fetus syndrome
2) Reabsorbed (Vanishing twin syndrome)
3) Fetus papyraceus
Retained dead fetus syndrome can lead to __1__ in the mother.
You want to check __2__ and __2__ levels weekly.
1) DIC (Disseminated intravascular coagulopathy)
2) Platelets and fibrinogen
