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?
After 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
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