External Cephalic Version

Background

External cephalic version (ECV) is a procedure that externally rotates the fetus from a breech presentation to a cephalic presentation. Successful version of a breech into cephalic presentation allows women to avoid cesarean delivery, which is currently the largest contributing factor to the incidence of postpartum maternal morbidity. ^{[1, 2]}

Breech presentation occurs in 3-4% of all term pregnancies. ^{[3, 4]} Breech presentation ranks as the third most frequent indication for cesarean section, following previous cesarean section and labor dystocia. More than 90% of breech fetuses are delivered by planned cesarean section. ^{[5, 6]} Approximately 12% of cesarean deliveries in the United States are performed for breech presentation, not including repeat cesarean sections secondary to a history of a prior cesarean indicated for breech presentation.

Since the results of the Term Breech Trial ^[7] recommended cesarean section for breech fetuses at term, ECV has resurfaced as a valuable maneuver. ^[8] ECV enjoyed great popularity in the 1970s, although its use decreased after reports of increased perinatal mortality associated with the procedure. These cases may have been caused by undue force being applied to the maternal abdomen, as well as the concomitant perception of planned cesarean section as a safer alternative to ECV or breech vaginal delivery. ^{[3, 4]}

ECV has been clearly shown to decrease the incidence of breech presentation at term, thereby reducing the cesarean section rate. ^[3] The safety of ECV, described later in this article, has been well-studied and confirmed. In accordance with the recommendations of the American College of Obstetricians and Gynecologists (ACOG), Royal College of Obstetricians and Gynaecologists, the Dutch Society for Obstetrics and Gynaecology, and Royal Dutch Organization for Midwives, ECV should be available and offered to all women near term with breech presentation who do not have any contraindications to the procedure. ^{[3, 4, 9, 10, 11, 12, 13]} In the properly selected patient, ECV is considered to be a safe and effective procedure to convert babies from breech to vertex presentation. ^[14]

Cesarean section is considered the largest contributing factor to maternal morbidity after childbirth ^[8] and routine use of ECV could potentially reduce the rate of cesarean delivery by about two thirds. ^[6] The use of tocolytics and regional anesthesia should be offered to all women who desire an external cephalic version.

Indications

Barring contraindications, ECV is recommended by several national organizations for all women with an uncomplicated singleton fetus in breech presentation at term to improve their chances of having a cephalic vaginal birth, ^[15] including ACOG, the Royal College of Obstetricians and Gynaecologists, the Dutch Society for Obstetrics and Gynaecology, and Royal Dutch Organization for Midwives. ECV should be available and offered to all women near term with breech presentation who do not have any contraindications to the procedure. ^{[3, 4, 9, 10, 11, 12, 13]}

Breech fetal presentation occurs when the fetal vertex is in the fundus of the uterus with the buttocks, legs, or feet presenting. There are four types of breech presentations:

• Frank breech occurs when the fetus’s legs are extended up to its head and the buttocks only are the presenting fetal part

• Complete breech occurs when the fetus’s hips and knees are flexed but the feet do not extend below the fetal buttocks

• Incomplete breech occurs when one or both hips are extended resulting in one or both feet or knees falling below the breech, so that the knee or foot is the presenting part

• Footling breech occurs when one or both legs are extended below the fetus’s buttocks

While the etiology of a breech presentation is not always clear, there are both fetal and maternal factors that can be causative. If there is more relative room for the fetus to move around, then there is a greater chance of malpresentation. Prematurity is the most common factor associated with malpresentation due to a smaller fetus and a relatively larger volume of amniotic fluid. As pregnancy continues and the volume of amniotic fluid diminishes in relationship to fetal size, the fetus is usually found in a presentation that allows the least constriction, that is, a longitudinal orientation with the buttocks and flexed thighs in the uterine fundus.

Similarly, polyhydramnios is associated with a higher rate of malpresentation. High parity is also a risk factor for breech presentation of the fetus due to a more spacious and lax uterine cavity. Conversely, if there is too little room for a fetus to move or the fetus is unable to move adequately, then a fetus in breech presentation may not be able to rotate into a cephalic presentation prior to delivery.

Examples of anatomical restraints that may restrict fetal movement into the vertex presentation include extended fetal legs, placental implantation (cornual or previa), contracted maternal pelvis, mullerian duct anomalies, leiomyomata, tumors, certain fetal anomalies (hydrocephaly, sacrococcygeal teratoma), and multiple gestation. ^{[16, 17, 18, 19, 20]}

A fetus that has altered mobility, such as with fetal neurologic impairments, myotonic dystrophy, or short umbilical cord, is less likely to move into the vertex presentation. ^{[21, 22]}

Contraindications

Contraindications to ECV exist either when the procedure may put the fetus in jeopardy or when the procedure is very unlikely to succeed. Clearly, if cesarean delivery is indicated for reasons other than breech presentation, ECV is contraindicated. ^[23] Placenta previa or abruptio placentae, nonreassuring fetal status, intrauterine growth restriction in association with abnormal umbilical artery Doppler index, isoimmunization, severe preeclampsia, recent vaginal bleeding, and significant fetal or uterine anomalies are also contraindications for ECV.

Other contraindications to ECV include ruptured membranes, fetus with a hyperextended head, and multiple gestations, although ECV may be considered for a second twin after delivery of the first.

Relative contraindications include maternal obesity, small for gestational age fetus (less than 10%), and oligohydramnios because they make successful ECV less likely. ^[24] Previous uterine scar from cesarean delivery or myomectomy may also be a relative contraindication for ECV.

Technical Considerations

Best Practices

We recommend that all ECV attempts be performed on the labor and delivery unit, with an operating room available if an emergency cesarean becomes necessary. In addition, labor and delivery provides easy access to fetal monitoring, anesthesia, and phlebotomy for maternal Rh status and blood count.

Procedure Planning

Prior to the procedure, fetal testing with a nonstress test or biophysical profile should be completed and reassuring fetal status should be documented. A bedside ultrasound should assess fetal position, amniotic fluid level, placenta location, and uterine cavity shape to help determine if the procedure should be performed and the likelihood of success. After the ultrasound assessment and fetal testing, informed consent should be obtained, taking in to account the information gathered from the fetal testing and ultrasound.

Outcomes

Breech presentation is associated with fetal abnormalities and, in and of itself, can be a marker for poor perinatal outcome. The incidence of childhood handicap following breech presentation has been found to be as high as 16% regardless of mode of delivery. It is unknown whether vaginal delivery of the breech fetus or abnormalities innate to the breech fetus are responsible for the perinatal outcome. ^[3]

Successful ECV is defined as conversion from malpresentation to cephalic presentation at the time of the procedure. The reported success rate of ECV ranges from 35 to 86%, with a commonly quoted figure of 50%. ^{[3, 9, 10, 11, 12, 13]}

Despite the low success rate, women who underwent ECV had a significant reduction in both noncephalic births and cesarean delivery compared to women who did not undergo ECV. ^[3] Barring contraindications, both ACOG and the Royal College of Obstetricians and Gynaecologists recommend offering ECV as an intervention for breech presentation at term.

Even with this recommendation, the percentage of women who are appropriate candidates for ECV who are not offered an attempt ranges from 4-33%. ^{[9, 10]} Moreover, of those who are offered ECV, reported rates of maternal refusal range from 18% to 76%. ^{[10, 11, 12, 13]}

With a 50% chance of successful ECV, 72.3% in multiparous women and 46.1% in nulliparous women, uncertainty about the success of attempted ECV likely explains the hesitancy of providers to offer the maneuver as well as maternal declination of this procedure. ^[25] In order to better counsel patients and providers on the likelihood of successful ECV, several factors such as parity, placental location, amniotic fluid index, and type of breech presentation have been studied. ^[26]

Factors that predict the outcome of ECV in breech pregnancies at term can be divided into clinical prognosticators, those that can be elicited from a history and physical examination, and ultrasound prognosticators.

Clinical prognosticators predictive of successful ECV include the following: ^[24]

• Multiparity

• Nonengagement of the presenting fetal part into the maternal pelvis

• Relaxed uterus

• Palpable fetal head

• Maternal weight less than 65 kg

All of these prognostic features lend to increased mobility of the fetus and better access to the fetus for the physician performing the procedure.

Ultrasonographic factors associated with successful ECV include the following ^{[27, 28]} :

• Amniotic fluid index greater than 10 cm

• Posterior placenta

• Lateral fetal spine position (facilitating operator’s ability to flex the fetal head and thereby form a more compact fetal mass)

• Complete breech fetal presentation

Kok et al proposed a prediction model that discriminated between women with poor chance of successful ECV (less than 20%) and good chance of success (greater than 60%) in breech pregnancies after 36 weeks gestational age. While this model has yet to be validated externally, it demonstrated that the prognosticators of multiparity, increasing maternal age, increasing estimated fetal weight until 3000 g, lateral placenta location, nonfrank breech presentation, and normal amniotic fluid (amniotic fluid index greater than 10 cm) were significantly associated with successful ECV. ^[26]

A prospective study conducted in Germany by Zielbauer et al demonstrated an overall success rate of 22.4% for ECV among 353 patients with a singleton fetus in breech presentation. ECV was performed at 38 weeks of gestation. Factors found to increase the likelihood of success were a later week of gestation, abundant amniotic fluid, fundal and anterior placental location, and an oblique lie. ^[29]

Factors associated with reduced success of ECV include the following:

• Nulliparity

• Firm maternal abdominal muscles

• Tense or contracting uterus

• Anterior or cornual placenta

• Decreased amniotic fluid volume (amniotic fluid index less than 10 cm)

• Ruptured membranes

• Low birth weight

• Presenting fetal part engaged into the maternal pelvis

• Maternal obesity

• Nonpalpable fetal head

• Posteriorly located fetal spine

• Fetal abdominal circumference below the fifth percentile

These factors decrease the likelihood of a successful ECV because they either make it more difficult for the physician to manipulate the fetus (maternal obesity and small fetus) or they decrease mobility of the fetus.

Successful ECV is significantly less likely in nulliparous women. This is explained by the increased abdominal wall musculature and uterine tone when compared to parous women. It is hypothesized that increased tone in the uterus and abdominal wall in nulliparous women could predispose to extended fetal legs and therefore frank breech presentation, an independent factor that lessens the chance of successful version. Ferguson et al noted that even when tocolytics were used routinely with attempted ECV, uterine relaxation in nulliparous women was rarely as complete as that achieved in parous women. ^[27]

Placental position may alter the intrauterine shape, lessening the space available for the traditional "forward roll" or "backward flip" used to rotate the fetus into cephalic presentation. Thus, cornual placentation is also associated with a lower rate of successful ECV. ^{[16, 17, 18, 19, 20]}

There are two additional procedural factors that are associated with decreased success rates. Higher levels of pain with ECV attempts are more likely to occur when greater force is applied, which is thought to indicate that the presenting fetal part is engaged and not turning readily. ^[3] In addition, ECV is abandoned earlier when pain is reported. ^{[27, 30]} Similarly, ECV is less successful when multiple attempts are made to turn the fetus. Again, the number of unsuccessful attempts at turning a fetus is frequently related to a fetus being more engaged in the maternal pelvis or other factors that decrease mobility of the fetus. ^[3]

ECV after Prior Cesarean Section

Although no large studies have evaluated the safety of ECV following cesarean delivery, several smaller case series have supported its use. ^{[31, 32, 33, 34, 35, 36, 37]} The controversy over ECV after cesarean is twofold. First, it is unknown what effect the abdominal manipulations of ECV have on a uterine scar. Second, although the current ACOG recommendation supports vaginal birth after cesarean, a physiologic risk to uterine integrity similar to ECV, many practitioners remain uncomfortable with this practice. ^[3]

In their prospective cohort study and review of the literature, Abenhaim et al found an overall success rate of ECV in women with a previous cesarean to be 50% from their data, and an overall success rate from the pooled literature of 71%. Given rates of success similar to women without a previous cesarean section, they concluded that concern over the success and safety of ECV in women with prior cesarean section is unwarranted and should not deter an attempt at ECV. Adverse outcomes were not addressed in this study. ^[14]

Flamm et al reported a 92% success rate among 56 patients with a previous cesarean section who attempted ECV without serious maternal or neonatal complications. ^[32] Schachter et al. reported success in all 11 ECV attempts after cesarean section when ritodrine was used to promote uterine relaxation. The only reported abnormality in that study was a fetal heart rate tracing with transient tachycardia in one fetus after the procedure that resolved after 30 minutes. All uterine scars, when examined either at surgery or by postpartum manual uterine exploration, showed no signs of dehiscence. ^[37]

In their case report of 38 women, Meeus et al reported a 65.8% success rate and no uterine ruptures in those women with previous cesarean who attempted ECV. There was one episode of vaginal bleeding after ECV, but after elective repeat cesarean, no placental abruption was noted and there were no adverse outcomes to mother or baby. All women who delivered vaginally after successful version (76%) underwent immediate postpartum examination to evaluate the uterine scar and no uterine ruptures were noted, but one uterine scar dehiscence was noted at the time of elective cesarean section performed 24 hrs after failed ECV. The study concluded that, after fetal weight assessment by clinical examination and ultrasonography, clinical examination of the pelvis and well-documented indications for prior cesarean delivery, ECV is acceptable and effective in women with a prior low transverse uterine scar. ^[38]

Ultimately, larger randomized trials are needed before definitive conclusions can be made.

Approach Considerations

An algorithm for patient management with external cephalic version is shown in the image below.

External Cephalic Version

During ECV, practitioners place their hands on the maternal abdomen to gently turn the fetus from breech to cephalic presentation.

When the patient has been deemed an appropriate candidate for ECV and she has signed the consent form, a tocolytic agent plus or minus a spinal or epidural anesthesia should been given.

An ultrasound or other means of assessing the fetal heart rate should be immediately available during the entire procedure. It is helpful to put ultrasound gel on the maternal abdomen to allow the practitioner’s hands to slide easily.

When the uterus is relaxed, the breech or feet should be elevated out of the maternal pelvis.

If one practitioner is performing the ECV, one hand is placed on the fetal head and the other is on the fetal buttocks.

If two practitioners are performing the ECV, one controls the fetal head while the other controls the fetal buttocks.

Usually a forward roll is attempted first.

A backward roll can follow if the forward roll is unsuccessful.

The fetal heart rate should be checked every few minutes and all maneuvers halted if the fetal heart rate is not reassuring. If the heart rate is repeatedly abnormal, the procedure should stop. The procedure should also be aborted for maternal discomfort not tolerated by the patient.

Although there are no large studies evaluating the number of ECV attempts, most studies attempt ECV no more than 3 or 4 times. If ECV is unsuccessful after 3 to 4 attempts, the fetus is unlikely to turn and the procedure should end.

After the ECV, the fetus should be monitored until a reassuring tracing is obtained.

Alternative Approaches

Expectant Management

Expectant management is always an alternative to any procedure or treatment. The likelihood of spontaneous conversion to cephalic presentation from breech presentation at term is quoted as 3%. ^[15]

In one study, the overall rate of spontaneous cephalic version following a failed ECV attempt was as high as 6.6%, with 2.3% rate in nulliparous women and 12.5% in multiparous women. ^[39]

Delivery by Cesarean

Another option is either planned or unscheduled cesarean delivery.

Trial of Labor

Trial of labor of a persistently breech fetus is theoretically an option. However, since the Term Breech Trial ^[7] was published supporting cesarean delivery over breech vaginal delivery to minimize perinatal morbidity and mortality, many providers will not offer vaginal delivery of a breech fetus as the standard of care.

In carefully chosen patients such as a multiparous female with a proven pelvis, a term infant, and achievement of complete cervical dilation, trial of labor may be an option as long as the patient is aware of the risks, benefits, and alternatives.

Version During Labor

Although sparse literature exits, ECV after the onset of labor with intact membranes for breech presentation is considered safe. Tocolytics have been used for uterine relaxation during labor to facilitate ECV in two small case studies. ^{[32, 40]}

Advantages of this strategy include allowing maximum time for fetal growth and development before the intervention, allowing ample opportunity for spontaneous version to cephalic presentation, continuous monitoring of the fetus until delivery, readily available cesarean delivery if needed, and administration of Rho(D) immune globulin may be delayed until fetal blood type is known after delivery.

Potential disadvantages of this approach include a tense uterus, advanced gestational age (and therefore larger fetal size and relatively lower amniotic fluid index), and the possibility that the opportunity for ECV will be lost from rupture of membranes or rapid progression of labor.

Postural Maneuvers

Postural maneuvers to convert a fetus from breech to cephalic presentation are another alternative to ECV. These maneuvers include pelvic elevation either in the hands-and-knees position or supine with a wedge supporting the pelvis. There is no high-quality evidence to support the efficacy of such maneuvers.

A systemic review involving 392 women found that, when compared with no intervention, there was no significant effect of postural maneuvers on the rate of breech births. ^{[41, 42]} The benefit of these maneuvers is that they can be done by the patient at home with very little risk to the mother or fetus.

Moxibustion and Acupuncture

Moxibustion is a practice in which a Chinese herb is burnt close to an acupuncture point on the skin. For version of the breech fetus, this is acupuncture point bladder 67 (BL67), at the tip of the fifth toe. This procedure is performed 20-60 minutes once or twice a day, either daily or twice weekly for 1-2 weeks. ^[43]

Several systemic reviews have supported moxibustion as a safe and effective tool for facilitating version. One study reported a higher rate of successful version in the moxibustion group as compared to observation or postural maneuvers (72.5% vs. 53.2%). ^[43] Similarly, a Cochrane review found that moxibustion reduced the need for ECV. ^[44]

However, these results are clouded by significant heterogeneity among the trials reviewed, significant patient crossover, lack of sham moxibustion control, and small number of women who pursued moxibustion alone as an intervention for version. Thus at this time, there is insufficient information to recommend for or against the use of moxibustion for version of the breech fetus. ^{[43, 44, 45]}

Patient Education & Consent

Informed consent should discuss the reason for the ECV, how the procedure will be done, the medications that will be used and their potential side effects, the benefits and risks of the procedure, the likelihood of success (taking in to account the results of the fetal testing and bedside ultrasound), and the management plan if the procedure is successful or unsuccessful. Only when the patient understands everything that was discussed and agrees to the procedure should the procedure commence.

Pre-Procedure Planning

The appropriate timing of performing ECV is currently under debate. Some posit that ECV may be more successful prior to 36 weeks gestation as the average fetus is smaller, not yet engaged into the maternal pelvis, and has proportionately more amniotic fluid. Others argue that patients who have completed 36 weeks of gestation are preferred candidates for ECV given high rates of spontaneous version (25% of fetuses are breech at 28 weeks while only 3-4% are breech at term), high risk of spontaneous reversion after successful version of a preterm fetus (due to smaller fetus, lack of engagement, and greater amniotic fluid index), and the improved outcome of emergency delivery of a term infant should complications arise during attempted version. ^{[46, 47, 48, 49, 50]}

The Early External Cephalic Version Trial, a prospective trial, randomized patients with a singleton breech fetus to ECV at 34-36 weeks of gestation (early ECV group) or to ECV at 37-38 weeks of gestation (delayed ECV group). ^[15] The practitioners were permitted by the protocol to repeat an ECV if the fetus reverted to a noncephalic presentation prior to delivery. While the early ECV group had a lower rate of malpresentation at delivery than the late ECV group (57% vs 66%), the result was not statistically significant. On the other hand, more fetuses reverted to breech presentation in the early ECV group than the delayed ECV group (12% vs 6%). The cesarean section rate was not statistically different between the two groups, with 64.7% of patients in the early ECV group and 71.6% of patients in the delayed ECV group requiring a cesarean section. As there were only 233 women included in the study, comparing complication rates between the groups was not possible.

Similarly, a randomized trial by Kasule et al studying ECV attempts between 33 and 36 weeks gestation found no significant difference between the cesarean delivery rates of patients with an ECV attempt and controls who did not undergo ECV. ^[51] Furthermore, in a Cochrane review of the literature, Hutton et al found that compared with no ECV attempt, ECV attempted before term reduces noncephalic births. ^[52]

Hutton et al reinvestigated early versus delayed attempt at ECV in their Early External Cephalic Version 2 Trial in 2011. Although their trial did not find higher risks of adverse outcomes for infants in the early attempt group, their results suggested that early ECV attempt may be associated with higher risk of preterm birth. This could be explained by preterm labor brought on by manipulation of the uterus. Overall, they concluded that ECV initiated at 34–35 weeks of gestation compared with 37 or more weeks of gestation increases the probability of vertex presentation at birth, but does not significantly reduce the rate of caesarean delivery and may increase the rate of preterm birth. ^[53]

While it seems tempting to perform an early ECV due to the increased rate of success, there are two major disadvantages. One, since the fetus is more likely to spontaneously revert to breech presentation after an early ECV, the patient may have to undergo additional ECV attempts, incurring the risks again of the procedure and medications as well as the discomfort. Two, if complications arise during the procedure between 34-36 weeks that necessitate an emergent delivery, the fetus is at significantly higher risk for having complications related to prematurity than a fetus born after 36-37 weeks of gestation.

In addition, the end result which the physician is trying to prevent, a cesarean section, is identical whether an ECV is performed prior to 36 weeks or after 36 weeks of gestation. Thus, we recommend a first attempt at ECV after 36 weeks gestation, as it provides a high rate of success (approximately 58%) with a significantly lower rate of complications due to prematurity should the fetus have to be delivered at the time of the procedure. If unsuccessful, it is reasonable to attempt retrial of version using tocolytics and/or regional anesthesia during a repeat attempt.

Further trials are needed to confirm this finding and to rule out increased rates of preterm birth, reversion to breech, or other adverse perinatal outcomes. ACOG guidelines issued in 2020 recommend that ECV should be performed starting at 37+0 weeks, in order to reduce the likelihood of reversion and to increase the rate of spontaneous version. ^[54]

Patient Preparation

Anesthesia

Controversy exists in the literature over whether or not regional anesthesia during an ECV can improve the success rate, resulting in a decrease in cesarean section rate, without increasing the complication rate. Proponents of regional anesthesia claim that patients are more comfortable and the abdominal wall is more relaxed, leading to higher success rates. ^[55] Others believe that regional anesthesia allows the practitioners to use excessive force, thus increasing the risk of placental abruption, uterine rupture, and fetal compromise or death. General anesthesia has been completely abandoned due to a fetal mortality rate of 1%. ^[56]

There are five studies that compare the use of spinal anesthesia to no anesthesia for ECV. All of the studies used a tocolytic agent for all patients in both the control and intervention groups, and all of the studies performed ECV at or beyond 36 weeks of gestation. In 102 patients, 50 who received spinal anesthesia and 52 without anesthesia, Dugoff et al found no difference between the two groups. There was an ECV success rate of 44% in the spinal group and 42% in the control group. The only adverse event was transient fetal tachycardia in 17 patients. ^[57] Similarly, studies by Delise and Holland did not find a statistically significant difference in rate of successful ECV when using spinal anesthesia, 41.4% versus 30.4% and 52.9% vs 52.6%, respectively. ^{[58, 59]}

There were two trials performed by Weiniger, one evaluating the use of spinal anesthesia for ECV in nulliparous women and the other evaluating the use in multiparous women. Both were randomized control trials. In nulliparous women, the ECV success rate was 66.7% in the spinal group and 32.4% in the control group. ^[60] This revealed a fourfold higher odds of success if spinal anesthesia was used. In 15 patients in the control group who had an unsuccessful ECVs due to pain, subsequent spinal anesthesia was offered and 11 of those patients went on to have a successful ECV. Of note, the study began using ritodrine as a tocolytic and concluded using nifedipine and found no difference in ECV success rates between these two tocolytic agents.

In Weiniger’s trial evaluating spinal anesthesia for ECV in multiparous women, there were 64 patients, of whom 31 received spinal anesthesia and 33 patients had no anesthesia. The success rate was 87.1% with spinal anesthesia and 57.5% in the control group. ^[61] In both the nulliparous and multiparous trials, there were no adverse fetal outcomes. There was a statistically significant difference in maternal hypotension due to spinal anesthesia, but again this did not result in any adverse fetal outcomes or increase in cesarean section rate due to nonreassuring fetal status. There were two nulliparous patients in the spinal anesthesia group that developed a spinal headache. One received a blood patch. Thus, there still remains conflicting evidence as to whether or not spinal anesthesia increases the rate of successful ECV. It does not, however, seem to increase the risk of adverse fetal outcomes.

A trial by Cherayil et al offered a spinal or epidural to women who had an unsuccessful ECV attempt without anesthesia. Of those who agreed to participate in the trial, 4 of 5 nulliparous women had a successful second ECV attempt using spinal anesthesia, and 1 of 1 had a second ECV attempt using epidural anesthesia. In multiparous women, 100% had a successful second ECV attempt using a spinal or epidural anesthesia. ^[62] Although the numbers are small, it seems that, from this trial and the trial by Weiniger et al, utilization of regional anesthesia following a failed ECV attempt without anesthesia significantly improves success rates.

One trial evaluated the use of a combined spinal and epidural for ECV. Sullivan et al performed a randomized control trial with 95 patients, 47 patients who were randomized to the combined spinal and epidural group and 48 patients who received intravenous fentanyl. There was no significant difference in ECV success rate between the two groups, with 47% in the combined spinal and epidural group versus 31% in the fentanyl group. ^[63]

At least five trials compare epidural anesthesia in addition to a tocolytic for ECV at or beyond 36 weeks of gestation. A retrospective study by Carlan et al found that the overall success rate of ECV was 59% with an epidural and 24% without an epidural. ^[64] In the epidural group, only 46% of the patients had a cesarean section, whereas 89% of the patients without an epidural had a cesarean section. There was no significant difference between the two groups in the rates of bradycardia, placental abruption, Apgar scores, or umbilical artery pH.

Schorr et al performed a prospective randomized control trial comparing 35 women who had an epidural for ECV to 34 women who had no anesthesia for ECV. Successful ECV was completed in 69% of the women with an epidural but only 32% of those without an epidural. ^[65] Schorr et al found that 34% of the patient in the epidural group underwent a cesarean section compared to 79% in the control group. There was no difference in fetal or maternal adverse outcomes between the two groups.

Mancuso et al also performed a larger prospective randomized control trial evaluating epidural anesthesia versus no anesthesia for ECV at term. There were 54 patients in each group and neither had any maternal or fetal adverse outcomes. The success rate for ECV with an epidural was 59% versus 33% without an epidural. Fifty-four percent of the epidural group had a vaginal delivery versus 24% in the control group. ^[66]

Yoshida et al looked at their group’s ECV success rate before they began offering regional anesthesia to the success rate after regional anesthesia was offered. Their overall ECV success rates rose from 56% to 79% after regional anesthesia was offered. The cesarean section rate dropped from 50% to 33% in the term breech population. ^[67]

Two meta-analyses have been able to put all of this information together since none of these trials have large sample sizes. MacArthur et al included all trials that used any type of general or regional anesthesia for ECV. The primary outcome was immediate success of ECV attempt. Four studies met their criteria with a total of 480 patients, of whom 238 received central axial anesthesia and 242 did not receive any anesthesia. The anesthesia group had a 50% success rate while the control group had a 34% ECV success rate. Thus, when using regional anesthesia, a woman is 1.5 times more likely to have a successful ECV. ^[68]

Bolaji et al ^[69] found similar results in their meta-analysis that included seven randomized control trials. In 681 women, 339 women received either epidural or spinal anesthesia, 47 women received intravenous fentanyl, and 295 women had no anesthetic. The ECV success rate with regional anesthesia was 51.3% in contrast to 34.9% in those without anesthesia. More women had success with ECV with regional anesthesia with a corresponding reduction in the cesarean section rate.

The meta-analysis by Bolaji et al also found that ECV was 1.5 times more likely to succeed in the regional anesthesia group compared to the control group. In addition, Bolaji et al found a 30% reduction in cost using epidural anesthesia due to the decrease in cesarean section and resultant complication rate. ^[69]

A systematic review of randomized controlled trials found regional anesthesia (spinal and epidural) was associated with a higher external cephalic version success rate compared with intravenous or no analgesia; 59.7% compared with 37.6%, respectively. ^[70]

Thus, it seems that regional anesthesia increases the rate of successful ECV, with a resultant decrease in cesarean rate without increasing maternal or fetal morbidity and mortality. Therefore, we recommend that regional anesthesia be offered to all women at term who choose to have an ECV. Larger randomized controlled trials are needed before this should become a standard practice.

A study by Chalifoux et al reported that higher doses of intrathecal bupivacaine (≥ 2.5 mg) do not lead to an increase in procedural success. ^[71]

Tocolytic Use

While the use of tocolytics during ECV is common practice, their impact on success rates is questionable. Historically, numerous tocolytic agents were used to relax the uterus during ECV. Ritodrine, salbutamol, and nitroglycerin were all used without increasing success rates over the control group. ^{[72, 73, 74, 75]} Betamimetic tocolytics were then used to relax the uterus during an ECV with good success. Fernandez et al found an ECV success rate of 52% when 0.25 mg of terbutaline was given subcutaneously prior to the procedure compared to a 27% success rate in those given a placebo. ^[76] Thus, terbutaline became the tocolytic of choice for ECV.

As nifedipine gained popularity as a tocolytic for preterm labor due to its efficacy and favorable side effect profile, many researchers looked at nifedipine as an alternative to terbutaline for tocolysis during ECV. Two different randomized trials revealed increased success rates when using terbutaline over nifedipine. ^{[77, 78]} A double-blind randomized trial by Collaris and Tan compared 10 mg of oral nifedipine plus subcutaneous saline to an oral placebo plus subcutaneous terbutaline. The terbutaline group had a high ECV success rate compared to the nifedipine group (52% versus 34%). In addition, there was a decrease cesarean section rate in the terbutaline group compared to the nifedipine group (56.5% versus 77.3%). ^[79]

Because there is an increase in successful ECV while using terbutaline with a significant side effect profile limited to transient maternal tachycardia, we recommend that ECV be performed approximately 5-20 minutes after subcutaneous administration of terbutaline.

Complications

Despite the universal recommendation that women be offered ECV for breech presentation, many practitioners have been hesitant to routinely offer this service, not only because of questions of efficacy but also because of fears about the safety of this procedure.

In a series of 805 consecutive ECV attempts in nulliparous women at or beyond 36 weeks gestation and multiparous women at or beyond 37 weeks, the overall perinatal mortality was only 0.1%—a result not clearly associated with the procedure itself. The rate of suspected placental abruption was 0.1%. ^[15]

In the same study, emergency cesarean section was performed for 4 patients at the time of the attempted version (0.5%). Two had abnormal fetal heart rate tracings for more than 20 minutes after the procedure; one of these neonates was subsequently diagnosed with trisomy 21. A third woman experienced vaginal bleeding with a normal fetal heart rate tracing after a failed ECV. At the time of cesarean section, there was no definitive evidence of placental abruption. The fourth cesarean section was due to rupture of membranes during a failed ECV attempt. All three congenitally normal babies were born with normal Apgar scores and cord pH levels. Uterine rupture and fetal trauma were not experienced. The authors concluded that women should be counseled that ECV is extremely safe but has a 0.5% risk of emergency cesarean section at the time of the procedure. ^[15]

In another study by Collaris and Oei, the overall perinatal mortality was 0.16%. The most frequently reported complications were transient fetal heart rate changes (5.7%), persistent fetal heart rate changes (0.37%), and vaginal bleeding (0.4%). Fetomaternal hemorrhage occurred 3.7% of the time. The reported incidence of placental abruption was 0.12% and the rate of emergency cesarean was 0.43%. ^[80] There was also a 3% risk of spontaneous reversion to breech presentation after successful ECV at or beyond 36 weeks gestation. ^[15]

We recommend counseling patients of a 0.5% risk of emergency cesarean section, perinatal mortality of < 0.1%, persistent fetal heart rate changes of 0.37%, spontaneous reversion to breech of 3%, and placental abruption of 0.1%. ^{[15, 80, 38]} The overall failure rate of ECV is approximately 50%, with a success rate of 72.3% in multiparous women and 46.1% in nulliparous women. ^[25]