Lecture 19: Multfetal Gestation and Malpresentation Flashcards
How does the nature of the membranes for monozygotic twins change if time of cleavage is between 0-3, 4-8, 9-12, or >13 days?
- 0-3 days = dichorionic, diamniotic
- 4-8 days = monochorionic, diamniotic
- 9-12 days = monochorionic, monoamniotic
- >13 days = conjoined twins
What is the most common presentation of membranes for monozygotic twins?
Monochorionic, diamniotic due to cleaveage at days 4-8
Which presentation of monozygotic twins is the most dangerous since there are not separating amnions?
Monochorionic monoamniotic
2/3’s of spontaneous twins are (mono- or dizygotic)?
Dizygotic
Having dizygotic twins is 2x more common when?
Maternal age > 35 y/o
What is the most important step after diagnosing a twin pregnanc?
Determination of zygosity!
How can a dizygotic twins be determined on U/S?
- Different fetal gender
- Visualization of thick amnion-chorion septum
- “Peak” or “inverted V” sign at base of septum
What is characteristic of the dividing membrane seen on U/S for monozygotic twins?
Fairly thin
90% of interplacental vascular anastomoses occur in what type of twins and what is the most common type of anastomosed vessels?
- 90% occur in monochorionic twins
- Most common type is arterial-arterial
In twin-twin transfusion syndrome both twins are at risk of demise from what?
Heart failure
What are treatment options for twin-twin transfusion syndrome?
- Serial amniocentesis w/ amniotic fluid reduction has been historically done
- Laser photocoagulation of the anastomosis vessles on the placenta is performed nowadays
What occurs in Acardiac Twin?
- Arterial to arterial anastomoses between twins
- Recipient twin, being perfused in reverse direction w/ poor oxygenated blood fails to develop normally
- Fully formed LE’s w/ NO anatomic structures cephalad of abdomen
What is the most frequent umbilical cord abnormalities seen in monozygotic twins?
Velamentous umbilical cord insertions
In velamentous cord insertion, the umbilical cord inserts into the fetal membranes (choriamniotic membranes), then travels within the membranes to the placenta (between the amnion and the chorion). The exposed vessels are not protected by Wharton’s jelly and hence are vulnerable to rupture.
If retained dead fetus syndrome occurs >20 weeks gestation what complication can develop in the mother; how should she be managed?
- Can devlop DIC
- Check platelets and fibrinogn levels weekly
What is fetus papyraceus?
When retained dead fetus syndrome occurs >12 weeks and the fetus shrinks, dehydrates, and flattens
With multifetal gestations how often should serial U/S’s for intrauterine growth be performed and starting when?
q 4-6 weeks begin at 24 weeks
When should mother with monoamniotic twins be hospitalized and they should be delivered at how many weeks; WHY?
- Hospitalize at 26 weeks and deliver at 32 weeks
- Secondary to ↑ risk of lethal cord entaglement
During vertex-vertex presentation the second twin is at increased risk for what complications; should be prepared for what complication in mother?
- 2nd twin = ↑ risk of cord prolapse, placental abruption, and malpresentation
- Be prepared for postpartum hemorrhage 2’ to uterine atony
If first twin is vertex but other twin is transverse or breech how should they be delivered?
CAN be vaginally, but will often be by C-section
What is the most common breech presentation?
- Frank
- Thighs are flexed
- LE’s are extended at knee
Who is a candidate for external cephalic version (ECV) to get baby into vertex position?
36 weeks gestation NOT in labor
Before performing external cephalic version (ECV) patient should be NPO for how long?
7 hours
Which breech position must baby be in to consider vaginal delivery and must be at what gestational age?
- Must be in frank or complete breech presentation
- Gestational age >37 weeks
- Fetal head MUST be flexed
What is the standard of care in most practices in terms of how to deliver a breech presenation?
All by C-section
If doing a vaginal breech delivery how far should the baby be out before applying any traction?
Allow fetus to deliver to the scapulae
Which special type of forceps are used in assisted breech deliveries?
PIPER forceps
With a face presentation the fetal chin is the point of designation which of these babies CAN and which CANNOT be delivered vaginally?
- Mentum anterior CAN deliver vaginally (MAV)
- Mentum posterior CANNOT; must do C-section
What is a compound presentation?
When fetal extremity (usually the hand) is found prolapsed alongside the presenting fetal part (head)
