Intrapartum management is largely determined by the presenta-tion of the twins. In general, if the first (presenting) twin isin the cephalic (vertex) presentation, labor is allowed to progress to vaginal delivery, whereas if the presenting twin is in a position other than cephalic, cesarean delivery is often performed. During labor, the heart rate of both fetuses is monitored separately. Approaches to the delivery of twins vary,depending on gestational age or estimated fetal weight, presenta-tion of the twins, and the experience of the attending physicians. Regardless of the delivery plan, access to full obstetric, anes-thetic, and pediatric services is mandatory because cesarean delivery may be required on short notice. About 40% of all twin pairs enter labor with both in the cephalic (vertex) pre-sentation. After delivery of the first twin, if the second fetus remains cephalic, vaginal delivery of the second twin gen-erally proceeds smoothly. With proper monitoring of the second twin, there is no urgency in accomplishing the sec-ond delivery.
If the second twin is presenting in any way other than cephalic (40% of all twin deliveries), there are two primary manipulations that may affect vaginal delivery. The first is external cephalic version. Using ultrasonographic visual-ization, the fetus is gently guided into the cephalic presen-tation by abdominal massage and pressure (Figure 17.2A). The second maneuver is breech extraction, in which the physician reaches a hand into the uterine cavity, grasps the lower extremities of the fetus, and gently delivers the infant via breech delivery (Figure 17.2B). Delivering the second twin via cesarean delivery is another management option, but is usually reserved for inability to safely deliver vaginally.
The possibility of a prolapsed umbilical cord must always be borne in mind when delivery of twins is to be accomplished. Twin gestations in which the first twin is in the breech presentation (20% of all twin deliveries) are most often delivered via cesarean delivery. Some clinicians and their patients plan for cesarean delivery unless both fetuses are in a cephalic presentation.
Postpartum, the overdistended uterus may not con-tract normally, leading to uterine atony and postpartum hemorrhage.