Following delivery of the first twin, the presenting part of the second twin, its size, and its relationship to the birth canal should be quickly and careully ascertained by combined abdominal, vaginal, and at times, intrauterine examination. Sonography is a valuable aid. If the fetal head or the breech is fixed in the birth canal, moderate undal pressure is applied and membranes are ruptured. Immediately aterward, digital examination of the cervix is repeated to exclude cord prolapse. Labor is allowed to resume. If contractions do not begin within approximately 10 minutes, dilute oxytocin may be used to stimulate contractions.
In the past, the safest interval between delivery of the irst and second twins was frequently cited as <30 minutes. Rayburn and colleagues (1984) and others have shown that if continuous fetal monitoring is used, a good outcome is usually achieved even if this interval is longer. A direct correlation between worsening umbilical cord blood gas values and increasing time between delivery of irst and second twins has been shown (Leung, 2002; Stein, 2008). From review of 239 twin gestations, Gourheux and associates (2007) determined that mean umbilical arterial pH was signiicantly lower after the delivery interval exceeded 15 minutes. In a study of more than 175,000 twin pairs, Cheng and colleagues (2017) reached similar conclusions for maternal and perinatal morbidity.
If the occiput or breech presents immediately over the pelvic inlet, but is not ixed in the birth canal, the presenting part can often be guided into the pelvis by one hand in the vagina, while a second hand on the uterine fundus exerts moderate pressure caudally. A presenting shoulder may be gently converted into a cephalic presentation. Alternatively, with abdominal manipulation, an assistant can guide the presenting part into the pelvis. Sonography can aid guidance and allow heart rate monitoring. Intrapartum external version of a noncephalic second twin has also been described.
If the occiput or breech is not over the pelvic inlet and cannot be so positioned by gentle pressure or if appreciable uterine bleeding develops, delivery of the second twin can be problematic. To obtain a favorable outcome, an obstetrician skilled in intrauterine fetal manipulation and anesthesia personnel skilled in providing anesthesia to efectively relax the uterus for vaginal delivery of a noncephalic second twin are essential (American College of Obstetricians and Gynecologists, 2016). To take maximum advantage of the dilated cervix before the uterus contracts and the cervix retracts, delay should be avoided. Prompt cesarean delivery of the second fetus is preferred if no one present is skilled in the performance of internal podalic version or if anesthesia that will provide efective uterine relaxation is not immediately available.
With internal podalic version, a fetus is turned to a breech presentation using the hand placed into the uterus (Fig. 45-26). he obstetrician grasps the fetal feet to then efect delivery by breech extraction (Chap. 28, p. 548). As mentioned earlier, Fox and associates (2010) described a strict protocol for management of the delivery of the second twin, which included internal podalic version. hey reported that none of the 110 women who delivered the irst twin vaginally underwent a cesarean delivery for the second twin. Chauhan and coworkers (1r995) compared outcomes of 23 second twins delivered by internal podalic version and breech extraction with those of 21 who underwent external cephalic version. Breech extraction was considered superior to external version because less fetal distress developed. Additional information and illustrations of this procedure are found in Cunningham and Gilstrap 5 Operative Obstetrics, 3rd edition (Yeomans, 2017).