Multifetal Gestation and Malpresentation (Moulton) Flashcards
__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?
Cord entanglement is high
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, and fetal demise?
Monozygotic
When using US when determining zygosity for dizygotic twins you might see a different __1__ amongst the twins.
There may be visualization of a __2__ septum.
A __3__ 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 results do to cleavage occurring at?
13-15 days
With conjoined twins elective termination is an option if what is identified?
Cardiac or cerebral fusion
What has a 90% chance of occurring in monochorionic twins?
The most common type is?
1) Interplacental vascular anastomoses
2) Arterial-arterial
With interplacental vascular anastomoses, vascular communications between the 2 fetuses through the placenta can cause several problems such as?
1) Abortion
2) Polyhydramnios
3) Twin-twin transfusion syndrome (TTTS)
Twin-twin transfusion syndrome results secondary to uncompensated __1__ anastomoses 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
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
TTTS treatment consists of ____ of the anastomosis vessels on the placenta at specialized centers.
Laser photocoagulation
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
What umbilical cord abnormalities can be seen primarily with monochorionic twins?
1) Absence of umbilical artery
2) Velamentous umbilical cord insertions (insertion of the cord into the membranes rather than directly into the placenta)
The incidence of single fetal death in monozygotic twins in utero is up to 5% and if gestation is 20 weeks or greater __1__ can develop.
If gestation is < 12 weeks the dead fetus is __2__.
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) Disseminated intravascular coagulopathy
2) Platelets and fibrinogen
With the high risk of ____ and ____ close antepartum surveillance is required.
Preterm birth and preeclampsia
In the third trimester, cervical length of less than ____ at 24-28 weeks doubled the risk for premature births in twins.
25mm
Monoamniotic twins should be delivered at __1__ weeks.
This is secondary to an increase risk for __2__.
Delivering is recommended at __3__ weeks for twins if pregnancy has no complications.
1) 32
2) Lethal cord entanglement
3) 38
What presentation occurs 40-50% of the time for twins?
Vertex-vertex
Which twin is at increased risk of cord prolapse, placental abruption and malpresentation?
Second twin
With delivery of twins be prepared for postpartum hemorrhage secondary to?
Uterine atony
__1__ and __1__ presentations can be delivered vaginally but often are delivered by cesarean section.
__2__ and __2__ twins are delivered via cesarean section.
1) Vertex-transverse and vertex-breech
2) Breech-breech and breech-vertex
What can occur secondary to prematurity and congenital anomalies?
1) Respiratory distress syndrome (RDS)
2) Intracranial hemorrhage
3) Birth asphyxia
Prematurity increases as the number of fetus increase, the average gestation at delivery for Triplets is ___ weeks.
The average gestational age at delivery for Quadruplets is ___ weeks.
1) 33
2) 29
Malpresentation refers to any fetal presentation other then __1__.
__2__ is the most common malpresentation.
1) Vertex
2) Breech
Breech presentation occurs when the fetal ____ or ____ presents into the maternal pelvis.
Buttocks or lower extremities
What is the most common factor associated with breech?
Prematurity
Which type of breech presentation is the most common where the thighs are flexed and the lower extremities are extended at the knees?
Which type of breech presentation is where the thighs and the lower extremities are flexed?
Which type of breech presentation is where one or both thighs are extended and one or both feet are below the buttocks?
1) Frank
2) Complete
3) Incomplete
____ involves applying pressure to the mother’s abdomen to turn the fetus in either a forward or backward somersault to achieve a vertex presentation.
External cephalic version
In order for vaginal delivery of breech presentation, the fetus must be in a ____ or ____ breech presentation.
Frank or complete
The standard of care now in most practices is to deliver all breeches by?
Cesarean section
When undergoing assisted breech vaginal delivery, a __1__ wrapped around the baby can be used for better traction.
You want to maintain cephalic flexion by applying pressure on fetal __2__, NOT fetal __3__.
__4__ is a tool that can be used in breech deliveries.
1) Towel
2) Maxilla
3) Mandible
4) Piper
__1__ presentation occurs when the presenting part of the fetus is between the facial orbits and anterior fontanelle.
The presenting diameter is the __2__ diameter.
__3__ bones are the point of designation.
1) Brow
2) Supraoccipitomental
3) Frontal
50-75% of brow presentation will convert to a face presentation through __1__ or a vertex presentation through __2__ and then deliver.
1) Extension
2) Flexion
The vertex presentation allows the ____ diameter to be the presenting diameter.
Suboccipitobregmatic
__1__ presentation is characterized by full extension of the fetal head and neck with occiput against upper back.
It can be seen frequently with fetal malformation such as __2__.
The fetal __3__ is chosen as point of designation.
1) Face
2) Anencephaly
3) Chin
The mentum must be __1__ in order to deliver a face presentation vaginally.
You can NOT deliver face presentation vaginally if the mentum is __2__. Will need to proceed with cesarean section.
1) Anterior
2) Posterior
The face presentation allows the ____ diameter to be the presenting diameter.
Trachelobregmatic
____ presentation is defined when a fetal extremity (usually the hand) is found prolapsed alongside the presenting fetal part (head).
Compound
