With version, fetal presentation is altered by physically substituting one pole of a longitudinal presentation for the other, or converting an oblique or transverse lie into a longitudinal presentation. Manipulations performed through the abdominal wall that yield a cephalic presentation are termed external cephalic version. Manipulations accomplished inside the uterine cavity that yield a breech presentation are designated intenal podalic version. This latter procedure is reserved for delivery of a second twin and described in Chapter 45 (p. 890).
External cephalic version (ECy) reduces the rate of noncephalic presentation at birth (Hofmeyr, 2015b). For breech fetuses near term, the American College of Obstetricians and Gynecologists (2016a,b) recommends that version be ofered and attempted whenever possible. Its success rate averages about 60 percent (de Hundt, 2014). For women with a transverse lie, the overall success rate is significantly higher.
In general, ECV is attempted before labor in a woman who has reached 37 weeks' gestation. Before this time, breech pre sentation still has a high likelihood of correcting spontaneously.
And, if ECV is performed too early, time may allow a rever sion back to breech (Bogner, 2012). Last, if attempts at version cause a need for immediate delivery, complications of iatro genic late-preterm delivery generally are not severe.
Absolute contraindications to external version are few. It is contraindicated if vaginal delivery is not an option, such as with placenta previa. Another is multifetal gestation. Relative contraindications are early labor, oligohydramnios or rupture of membranes, known nuchal cord, structural uterine abnor malities, fetal-growth restriction, and prior abruption or its risks (Rosman, 2013). While many consider a prior cesarean delivery a contraindication, a few small studies found ECV was not asso ciated with uterine rupture (Burgos, 2014; Keepanasseril, 2017;
Weill, 2017). At Parkland Hospital, we do not attempt version in these women. More data from clinical studies are needed.
Several factors can improve the chances of a successful attempt. These include multiparity, unengaged presenting part, nonanterior placenta, nonobese patient, and abundant amnionic fluid (Kok, 2009, 2011; Velzel, 2015). To augment the last parameter, Burgos and coworkers (2014) administered a preprocedurali2-L intravenous luid bolus. While this improved amnionic luid volume, it did not increase version success rates.
Patient counseling includes a discussion regarding small but real risks for placental abruption, preterm labor, and fetal compromise. Rarely, uterine rupture, fetomaternal hemorrhage, alloimmunization, amnionic luid embolism, and even death may also complicate attempts at external version. hat said, fetal deaths are rare, serious complication rates are typically very low, and emergent cesarean rates are 0.5 percent or less (Grootscholten, 2008; Rodgers, 2017). And even after successful EC, several reports suggest that the cesarean delivery rate does not completely revert to the baseline for vertex presentations. Specifically, dystocia, malpresentation, and nonreassuring fetal heart patterns may be more common in these fetuses completing successful version (Chan, 2004; de Hundt, 2014; Vezina, 2004).