82 Obstetrics and Gynecology Board Review •••
❍ Does fetal fibronectin have a predictive value in multiple gestations?
Most studies show a high negative predictive value and fairly high positive predictive value.
❍ Do twins develop pulmonary maturity at the same rate as singletons?
Twins appear to develop pulmonary maturity 3 to 4 weeks earlier than singletons.
❍ What are the two most common presentations of twins at the time of delivery?
The most common presentation of twins at the time of delivery is vertex-vertex (approximately 40%) followed
by vertex-breech (approximately 25%).
❍ How should vertex-vertex twins be delivered?
Vaginal delivery is recommended.
❍ How should vertex-nonvertex twins be delivered?
The delivery of vertex-nonvertex twins is controversial. Some data suggests that the Apgar scores are lower
and perinatal complications are increased by vaginally delivering the second nonvertex twin.
❍ What are the vaginal delivery options for the vertex-breech delivery?
Delivery options for second twin in a vertex-breech delivery include external cephalic version of the second breech
twin or internal podalic version and breech extraction.
❍ How should a nonvertex-presenting twin be delivered?
In general, cesarean delivery is the method of choice when the first twin is nonvertex.
❍ What is the minimum estimated fetal weight of a nonvertex second twin that you would consider
attempting a vaginal delivery?
1500 g.