About 25% of fetuses will be in breech presentation at 28 weeks, and this decreases to about 3% to 4% of term pregnancies. Most of these patients will be delivered by cesarean delivery. It is held that the overall cesarean delivery rate is higher than it should be, and efforts to prevent the first cesarean section often present obstetricians with the task of decreasing the number of cesarean deliveries they perform. One alternative to cesarean delivery is an external cephalic version (ECV). Simply, it is a procedure to change the presentation of the fetus from breech, tranverse, or oblique to vertex by applying pressure externally to the fetus through the gravid abdomen. The overall success rate for the procedure is about 58% and can lead to decreased cesarean delivery rates.
ECV can be attempted with malpresentation of the fetus such as breech, transverse and oblique presentations. Complete breech occurs when the fetus has the buttocks as the presenting part and the knees are flexed with the feet near the buttocks. Frank breech occurs when the buttocks are the presenting part, and the legs are extending with the feet near the fetal head. Incomplete breech involves one bent leg and one extended leg. Transverse presentations occur when the long axis of the fetus is at a right angle to the mother with the fetal head to one side of the maternal abdomen and the back noted to be either be up or down in relation to the rest of the fetal body. Oblique presentation is when the long axis of the fetus is at a 45-degree angle to the mother, with the fetal head usually in the right or left lower quadrants.
Indications for ECV include a fetus with greater than 36 weeks of gestation with malpresentation, reassuring fetal status, and no contraindications to vaginal delivery. Most practitioners will proceed with ECV at 37 weeks to decrease the risk of preterm delivery. Factors that may increase success include multiparity, transverse or oblique presentation, complete breech, adequate amniotic fluid, and unengaged presenting part. Factors that are associated with decreased success include nulliparity, advanced dilation, estimated fetal weight of less than 2,500 grams, anterior, lateral or cornual placenta, decreased amniotic fluid or ruptured membranes, maternal obesity, frank breech, fetal spine in the posterior position, and low station with an engaged presenting part.
One alternative to ECV is expectant management with possible spontaneous version, although most fetuses that will spontaneously change presentations to vertex will do so before 36 weeks gestation and are noted more often in multiparous than nulliparous women. Other alternatives are expectant management with a vaginal or cesarean delivery of the breech fetus.
Any contraindication to vaginal delivery would also be a contraindication to ECV. These include but are not limited to placenta previa, vasa previa, active genital herpes outbreak, and prior classical cesarean delivery. Prior low transverse cesarean delivery is not a contraindication to external cephalic version, although not much data is available on uterine rupture rates.
Antepartum ECV is contraindicated in multiple gestations, although it can be utilized for delivery of the second twin.
Consideration should be used in patients with severe oligohydramnios, nonreassuring fetal monitoring, hyperextended fetal head, significant fetal or uterine anomaly, fetal growth restriction, and maternal hypertension due to these situations being associated with a low likelihood of success of ECV and possible increased risk to the fetus from the procedure.
If a woman presents in labor with malpresentation, ECV could be a reasonable option if she is in early labor, the presenting part is unengaged, there is a normal amniotic fluid index, and no contraindications to vaginal delivery or ECV.
Not much equipment is necessary for this procedure as it is performed with the physician's own hands. Fetal monitoring and ultrasonography are necessary components for safety and reassurance.
An obstetrician experienced in external cephalic version is needed to perform an ECV. The procedure can be performed by one or two people. Not necessary in the room, but those that should be aware of the ECV procedure would be those needed in case of emergency cesarean delivery, such as nursing, operating room, and anesthesia staff.
In preparation for ECV, the fetal presentation must be determined by ultrasound and fetal well-being must be assessed, usually by a nonstress test. Contraindications are reviewed with the patient to confirm that they have none. Risks, benefits, and alternatives are reviewed with the patient, and informed consent is obtained. Rh status should be known before the procedure and anti-D immune globulin administered after the procedure if indicated.
Some practitioners choose to administer a tocolytic, usually terbutaline 0.25 mg subcutaneously, 15 to 30 minutes before the procedure, if are no contraindications. Data does not support either calcium channel blockers or nitroglycerin for tocolysis in this situation. Some practitioners choose to use regional anesthesia in the form of either a spinal or epidural, but data is insufficient to recommend this for all external cephalic version attempts, although it may add to success if tocolysis alone is not successful.
The patient is lying supine, with a sideways tilt with a wedge to keep pressure off the aorta and vena cava. If the fetal presentation is breech, then the breech is lifted out of the pelvis with one hand, and the other hand is used to apply pressure to the back of the fetal head to attempt a forward roll. If a forward roll is unsuccessful, then a backward roll can be attempted. If the fetus is in either a transverse or oblique presentation, similar manipulation of the fetus is used to attempt to move the fetal head to the pelvis, noting a shorter distance to move than if the fetus is in a breech presentation.
Intermittent use of ultrasonography during the procedure can be used to document fetal heartbeat and current presentation. The procedure should be abandoned if there is significant fetal bradycardia, discomfort to the patient, or if the procedure is not completed easily. Afterward, the patient should be monitored for at least 30 minutes, with fetal heart rate tracing and anti-D immune globulin given if indicated. Immediate induction is not recommended to minimize reversion, although this could be considered after 39 weeks of gestation. If ECV is unsuccessful, additional attempts can be made at the same admission or in one or more days following the initial procedure.
The most common complications associated with ECV are fetal heart rate abnormalities, occurring at a rate of 4.7%, but these usually are transient and improve upon completion or abandonment of the procedure. More severe complications of ECV occur at a rate of less than 1% and include emergency cesarean section, premature rupture of membranes, cord prolapse, vaginal bleeding, placental abruption, fetomaternal hemorrhage, and stillbirth. Although complications are rare, ECV should be attempted in locations where an emergency cesarean section can be performed. For this reason, some practitioners chose to perform ECV in the operating room, although this is not necessary.
Patients should be counseled on and offered ECV when appropriate. Some data show that only 20% to 30% of eligible candidates are offered ECV.
Women who have a successful ECV have a lower cesarean delivery rate than women who do not, although they are still at a higher risk of cesarean delivery than women with cephalic presenting fetuses and no ECV. ECV is cost effective if the probability of a successful ECV is greater than 32%.