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External Cephalic Version

Overview

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.

Breech presentation occurs in 3-4% of all term pregnancies.
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.
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
recommended cesarean section for breech fetuses at term, ECV has resurfaced as a valuable maneuver.
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.

ECV has been clearly shown to decrease the incidence of breech presentation at term, thereby reducing the cesarean section rate.
The safety of ECV, described later in this article, has been well-studied and confirmed. In accordance with the recommendations of the American Congress 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.
In the properly selected patient, ECV is considered to be a safe and effective procedure to convert babies from breech to vertex presentation.

Cesarean section is considered the largest contributing factor to maternal morbidity after childbirth
and routine use of ECV could potentially reduce the rate of cesarean delivery by about two thirds.
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,
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.

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.

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.

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.
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.
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.

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%.

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.
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%.
Moreover, of those who are offered ECV, reported rates of maternal refusal range from 18% to 76%.

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.
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.

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:

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:

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

Recently, 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.

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.

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.

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.
In addition, ECV is abandoned earlier when pain is reported.
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.

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.
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.

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.

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.
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.

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.

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

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