External Cephalic Version

Anatomy and Physiology

ECV can be attempted when managing breech presentations or fetuses with a transverse or oblique lie. Three types of breech presentation are established concerning fetal attitude: complete, frank, and incomplete, which is sometimes referred to as footling breech. In complete breech, the fetal pelvis engages with the maternal pelvic inlet, and the fetal hips and knees are flexed. In frank breech, the fetal pelvis engages with the maternal pelvic inlet, the fetal hips are flexed, the knees are extended, and the feet are near the head. In incomplete or footling breech, one (single footling) or both (double footling) feet are extended below the level of the fetal pelvis.

A fetus with a transverse lie is positioned with their long axis, defined as the spine, at a right angle to the long axis of the gravida. The fetal head may be to the right or left side of the maternal spine. The fetus may be facing up or down. The long axis of the fetus characterizes an oblique lie at any angle to the maternal long axis that is not 90°. An oblique fetus is usually positioned with their head in the right or left lower quadrants, although this is not universal.

Indications

ECV may be indicated in carefully selected patients. The fetus must be at or beyond 36 0/7 weeks of gestation with malpresentation, and there must be no absolute contraindications to vaginal delivery, such as placenta previa, vasa previa, or a history of classical cesarean delivery. Fetal status must be reassuring, and preprocedural nonstress testing is recommended. While ECV may be performed as early as 36 0/7 weeks gestation, many practitioners will delay ECV until 37 0/7 weeks gestation to ensure delivery of a term fetus.

ECV is more successful in multigravidas, those with a complete breech or transverse or oblique presentation, an unengaged presenting part, adequate amniotic fluid, and a posterior placenta. Nulliparous patients and those with an anterior, lateral, or cornual placenta have lower success rates. Patients with advanced cervical dilatation, obesity, oligohydramnios, or ruptured membranes also have lower success rates. Additionally, if the fetus weighs less than 2500 g, is at a low station with an engaged presenting part, is frank breech, or the spine is posterior, the success of ECV is decreased.[5] 

Evidence supports the use of parenteral tocolysis, most often with the beta-2-agonist medication terbutaline, to improve the success of ECV; most studies evaluating the various aspects of ECV aspects include using a tocolytic agent.[6][7][8][9] Data regarding the improved success of ECV incorporating regional anesthesia is inconsistent. 

Contraindications

Any contraindication to vaginal delivery would also be a contraindication to ECV. These contraindications include but are not limited to placenta previa, vasa previa, active genital herpes outbreak, or a history of classical cesarean delivery. A history of low transverse cesarean delivery is not an absolute contraindication to ECV.[10] The overall success rate of ECV in patients with a previous cesarean birth ranges from 50% to 84%; no cases of uterine rupture during ECV were reported in the four trials evaluating this outcome in patients with a prior cesarean delivery.[11][12][13][14]

Antepartum ECV is contraindicated in multiple gestations, although it can be utilized for twin gestations that would otherwise be suitable candidates for breech extraction.[15][16]

Patients with severe oligohydramnios, nonreassuring fetal monitoring, a hyperextended fetal head, significant fetal or uterine anomaly, fetal growth restriction, and maternal hypertension carry a low likelihood of successful ECV and a significantly increased risk of poor fetal outcomes; ECV in such situations requires careful consideration.

If a gravida who is otherwise a suitable candidate for ECV presents in early labor with fetal malpresentation, ECV may be a reasonable option if the presenting part is unengaged, the amniotic fluid index is within the normal range, and there are no contraindications to ECV or vaginal delivery. Data from the Nationwide Inpatient Sample from 1998 to 2011 noted a success rate of 65% for ECV performed in carefully selected patients during the admission for delivery.[17] ECV performed in this circumstance resulted in a significantly lower cesarean birth rate and hospital stay of greater than 7 days compared to patients with a persistent breech presentation at the time of delivery.[17]

Equipment

External cephalic versions should be attempted only in settings where cesarean delivery services are readily available. Therefore, the required equipment for ECV includes all such requirements for cesarean delivery, including anesthesia services. Access to tocolytic agents, bedside ultrasonography, and external fetal heart rate monitoring equipment is also required. Following ECV, fetal status must be assessed; nonstress testing is preferred. If nonstress testing is unavailable, Doppler indices of the umbilical artery, middle cerebral artery, and ductus venosus may be performed.[18]

Personnel

The personnel typically required to perform an ECV include:

• Obstetrician
• Labor and delivery nurse.

ECV may only be performed in a setting where cesarean delivery services are readily available. Personnel typically required for cesarean delivery include:

• Obstetrician
• Surgical first assistant
• Anesthesia personnel
• Surgical technician or operating room nurse
• Circulating or operating room nurse
• Pediatric personnel
• Note: for cesarean delivery, labor and delivery nurses may serve as surgical technicians, circulating, or operating room roles.

Preparation

Before attempting ECV, informed consent must be obtained; this should include tocolysis and neuraxial analgesia if those procedures will be performed. Some clinicians will obtain consent from the patient for potential emergency cesarean delivery at this time, although this practice is not universal. Additionally, an ultrasound examination should be performed to verify fetal presentation, exclude fetal and uterine anomalies, locate the placental position, and evaluate the amniotic fluid index. Many clinicians will evaluate preprocedural fetal status with a nonstress test. 

The current evidence supports the administration of terbutaline 0.25mg subcutaneously 15 to 30 minutes before the ECV but does not support using calcium channel blockers or nitroglycerin for preprocedural tocolysis.[19] While multiple studies report the increased success of ECV in patients who are administered epidural or spinal neuraxial anesthesia, overall data is insufficient to warrant a universal recommendation; neuraxial anesthesia may improve success rates for ECV in situations where tocolysis alone was unsuccessful.[20]

Technique or Treatment

The gravida should be supine with a leftward tilt using a wedge support to relieve pressure on the great vessels. ECV is best performed using a 2-handed approach.

If the fetal presentation is breech, lift the breech out of the pelvis with one hand and apply downward pressure to the posterior fetal head to attempt a forward roll. If a forward roll is unsuccessful, 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 try to move the fetal head to the pelvis.[21]

Fetal well-being should be evaluated intermittently with Doppler or real-time ultrasonography during ECV. ECV should be abandoned if there is significant fetal bradycardia, patient discomfort, or if a version is not achieved easily. After a successful or unsuccessful ECV, external fetal heart rate monitoring should be performed for 30 to 60 minutes. If the gravida is Rh negative, anti-D immune globulin should be administered.

Immediate induction of labor to minimize reversion is not recommended. If the initial attempt at ECV is unsuccessful, additional attempts can be made during the same admission or at a later date.

Complications

Complications of ECV are rare and occur in only 1% to 2% of attempts. The most common complication associated with ECV is fetal heart rate abnormalities, particularly bradycardia, occurring at a rate of 4.7% to 20%; these abnormalities 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 premature rupture of membranes, cord prolapse, vaginal bleeding, placental abruption, fetomaternal hemorrhage, emergent cesarean delivery, and stillbirth. Many of these rare complications require emergent cesarean delivery; some clinicians choose to perform ECV in the operating room, although this is neither necessary nor universal.[22]  

ECV is associated with changes in Doppler indices that may reflect decreased placental perfusion. It appears these changes are short-lived and have no detrimental effects on the outcomes of uncomplicated pregnancies. A recent prospective study investigating the effects of ECV on fetal circulation in the antepartum period noted no differences in the Doppler evaluation of the middle cerebral artery or ductus venosus; all studied patients remained stable and were discharged home after the procedure.[18] 

Clinical Significance

Some data indicate that only 20% to 30% of eligible candidates are offered ECV.[23] Patients who undergo a successful ECV procedure have a lower cesarean delivery rate than patients who do not but are still at a higher risk of cesarean delivery than patients with cephalic fetuses who do not require ECV. ECV is cost-effective if the probability of a successful ECV exceeds 32%. Overall, ECV is successful in 58% of attempts, reduces the risk for CS by two-thirds, and enables 80% of these patients to deliver vaginally.[24]

Enhancing Healthcare Team Outcomes

ECV is not a benign procedure and is most successful when performed under the care of an interprofessional team. Labor and delivery nurses play an integral role in the success of ECV as they frequently assist in the procedure, prepare the patient for ECV, and implement external fetal monitoring before, during, and after the procedure. Additionally, the support of emergent operating room staff promotes the safe delivery of a healthy fetus should complications arise during the ECV procedure. Clear and concise anticipatory interprofessional communication improves safety and outcomes for the gravida and the fetus should complications occur.