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
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What is the most common presentation of membranes for monozygotic twins?
Monochorionic, diamniotic due to cleaveage at days 4-8
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Which presentation of monozygotic twins is the most dangerous since there are not separating amnions?
Monochorionic monoamniotic
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2/3’s of spontaneous twins are (mono- or dizygotic)?
Dizygotic
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Having dizygotic twins is 2x more common when?
Maternal age > 35 y/o
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What is the most important step after diagnosing a twin pregnanc?
Determination of zygosity!
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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
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What is characteristic of the dividing membrane seen on U/S for monozygotic twins?
Fairly thin
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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
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In twin-twin transfusion syndrome both twins are at risk of demise from what?
Heart failure
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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
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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
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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.
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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
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What is fetus papyraceus?
When retained dead fetus syndrome occurs >12 weeks and the fetus shrinks, dehydrates, and flattens
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