External Cephalic Version: How to Increase the Chances for Success
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External cephalic version: How to increase the chances for success Henry Michael Lerner, MD Increasing the use of ECV in breech-presenting fetuses at term has the potential to turn the tide on cesarean delivery rates in this population. Certain techniques can help facilitate successful version and the likelihood of vaginal delivery, with low risk to mother and baby. bout 3% to 4% of all fetuses at term facilitating tools of tocolysis and neuraxial are in breech presentation. Since analgesia/anesthesia, is helping to reduce the A 2000, when Hannah and colleagues number of breech presentations in fetuses at reported finding that vaginal delivery of term and thus the number of cesarean deliv- IN THIS ARTICLE breech-presenting babies was riskier than eries and their sequelae—placenta accreta, cesarean delivery,1 most breech-presenting prolonged recovery, and cesarean deliveries neonates in the United States have been deliv- in subsequent pregnancies. Timing the ered abdominally2—despite subsequent ques- ECV procedure tioning of some of that study’s conclusions. page 28 Each year in the United States, approxi- Reluctance to perform ECV mately 4 million babies are born, and fetal is unfounded Risks of ECV malpresentation accounts for 110,000 to In the United States, the practice of offering 150,000 cesarean deliveries. In fact, about ECV to women who present with their fetus page 29 15% of all cesarean deliveries in the United in breech presentation at term varies tremen- States are for breech presentation or trans- dously. It is routine at some institutions but Neuraxial verse lie; in England the percentage is not even offered at others. analgesia/ 10%.3 Fortunately, the repopularized tech- Many ObGyns are reluctant to perform anesthesia nique of external cephalic version (ECV), ECV. Cited reasons include the potential for page 31 in which the clinician externally rotates a injury to the fetus and mother (and related lia- breech- or transverse-lying fetus to a vertex bility concerns), the ease of elective cesarean position (FIGURE, page 30), along with the delivery, the variable success rate of ECV (35% to 86%),4 and the pain that women often have Dr. Lerner is Assistant Clinical Professor, Department of Obstetrics with the procedure. According to the literature, and Gynecology, Harvard Medical however, these concerns either are unfounded School, Boston, Massachusetts. or can be mitigated with use of current tech- niques. Multiple studies have found that the risk of ECV to the fetus and mother is minimal, and that tocolysis and neuraxial anesthesia The author reports no financial relationships relevant to this article. can facilitate the success of ECV and relieve the pain associated with the procedure. CONTINUED ON PAGE 28 26 OBG Management | September 2017 | Vol. 29 No. 9 obgmanagement.com External cephalic version CONTINUED FROM PAGE 26 Indications for ECV only during labor. The advantages are that The indications for ECV include breech, the fetus has had every chance to move into oblique, or transverse lie presentation after vertex presentation on its own, the equip- 36 weeks’ gestation and the mother’s desire ment used to continuously monitor the fetus to avoid cesarean delivery. A clinician skilled during ECV is in place, and cesarean deliv- in ECV and a facility where emergency cesar- ery and anesthesia are immediately avail- ean delivery is possible are essential. able in the event ECV is unsuccessful. There are several instances in which ECV The major disadvantage of waiting until should not be attempted. labor is that the increased size of the fetus Contraindications include: makes ECV more difficult. In addition, the • concerns about fetal status, including non- membranes may have already ruptured, and reactive nonstress test, biophysical pro- the breech may have descended deeply into file score <6/8, severe intrauterine growth the pelvis. restriction, decreased end-diastolic umbil- ical blood flow • placenta previa Success rates in • multifetal gestation before delivery of first breech-to-vertex conversions twin In 2016, the American College of Obstetri- • severe oligohydramnios cians and Gynecologists (ACOG) reported an • severe preeclampsia average ECV success rate of 58% (range, 16% • significant fetal anomaly to 100%).6 ACOG noted that, with transverse • known malformation of uterus lie, the success rate was significantly higher. • breech with hyperextended head or arms Other studies have found a wide range of above shoulders, as seen on ultrasonography. rates: 58% in 1,308 patients in a Cochrane More controversial contraindications review by Hofmeyr and colleagues7; 47% in include prior uterine incision, maternal obe- a study by Beuckens and colleagues8; and Current practice sity (body mass index >40 kg/m2), ruptured 63.1% for primiparas and 82.7% for multipa- 9 is to wait until 36 membranes, and fetal macrosomia. ras in a study by Tong Leung and colleagues. to 37 weeks of These rates were affected by whether ECV gestation to was performed with or without tocolysis, perform ECV, Optimal timing with or without intravenous analgesia, and for the ECV procedure with or without neuraxial analgesia/anesthe- since most fetuses Current practice is to wait until 36 to sia (TABLE, page 29). spontaneously 37 weeks to perform ECV, as most fetuses move into vertex spontaneously move into vertex presenta- Likelihood of vaginal delivery after presentation by tion by 36 weeks’ gestation. This time frame successful ECV 36 weeks has several advantages: Many unneces- The rate of vaginal delivery after successful sary attempts at ECV are avoided; only ECV is roughly half that of fetuses that were 8% of fetuses in breech presentation after never in breech presentation.10 In successful 36 weeks spontaneously change to vertex5; ECV cases, dystocia and nonreassuring fetal many fetuses revert to breech if ECV is per- heart rate patterns are the major indications formed too early; and prematurity generally for cesarean delivery. Some experts have is not an issue in the rare case that immedi- speculated that the factors leading to near- ate delivery is required during or just after term breech presentation—such as an unen- attempted ECV. gaged presenting part or a mother’s smaller ECV during labor. Performing ECV during pelvis—also may be risk factors for dystocia labor appears to pose no increased risk to in labor. Despite this, the rate of vaginal deliv- mother or fetus if membranes are intact and ery of successfully verted babies has been there are no other contraindications to the reported to be as high as 80%.10 procedure. Some clinicians perform ECV As might be expected, post-ECV vaginal CONTINUED ON PAGE 29 28 OBG Management | September 2017 | Vol. 29 No. 9 obgmanagement.com CONTINUED FROM PAGE 28 deliveries are more common in multiparous TABLE Factors that affect the ECV success rate than in primiparous women. Increase ECV success rate Decrease ECV success rate Risks of ECV: Generally low and Transverse or oblique lie Ruptured membranes manageable Multiparity Macrosomic fetus Although multiple problems may occur with Amniotic fluid index >18 Relative oligohydramnios ECV, generally they are rare and reversible. For instance, Grootscholten and colleagues Breech unengaged Maternal obesity found a stillbirth and placental abruption Smaller fetus Primigravida status rate of only 0.25% in a large group of patients Patient with normal body Anterior placenta 11 who underwent ECV. Similarly, the rate mass index of emergency cesarean delivery was 0.35%. Mother’s inability to relax anterior Clinician experienced in ECV abdominal wall muscles In addition, Hofmeyr and Kulier, in their Cochrane Data Review of 2015, found no sig- Placenta on posterior wall of uterus Clinician’s inability to locate fetal head by palpation nificant differences in the Apgar scores and Complete (vs footling) breech pH’s of babies in the ECV group compared Contracting or tense myometrium with babies in breech presentation whose Tocolysis mothers did not undergo ECV.7 Results of Neuraxial analgesia/anesthesia other studies have confirmed the safety of ECV.12,13 Abbreviation: ECV, external cephalic version. One significant risk of ECV attempts is fetal-to-maternal blood transfer. spontaneously move into vertex Boucher and colleagues found that 2.4% of presentation.5 1,244 women who underwent ECV had a • Maternal positioning. There is no good positive Kleihauer-Betke test result, and, in evidence that such maneuvers are effective one-third of the positive cases, more than in changing fetal presentation.15 1 mL of fetal blood was found in maternal • Moxibustion and acupuncture. Moxi- Tocolysis, which 14 circulation. This risk can be minimized by bustion is inhalation of smoke from burn- relaxes the uterus, administering Rh (D) immune globulin to ing herbal compounds. In formal studies o and neuraxial all Rh-negative mothers after the procedure. using controls, these techniques did not analgesia/ Even these small risks, however, should consistently increase the rate of movement anesthesia, which 16–18 not be considered in isolation. The infrequent from breech to vertex presentation. relaxes anterior complications of ECV must be compared Likewise, studies with the use of acupunc- abdominal wall with what can occur with breech-presenting ture have not shown consistent success in muscles and reduces fetuses during labor or cesarean delivery: changing fetal presentation.19 ECV-associated complications of breech vaginal delivery, pain, can facilitate cord prolapse, difficulties with cesarean Methods to facilitate delivery, and maternal operative complica- ECV success ECV success tions related to present and future cesarean Two techniques that can facilitate ECV suc- deliveries. cess are tocolysis, which relaxes the uterus, and neuraxial analgesia/anesthesia, which Alternative approaches to relaxes anterior abdominal wall muscles and converting breech presentation reduces or relieves ECV-associated pain. of unproven efficacy Over the years, attempts have been made to Tocolysis address breech presentations with measures In tocolysis, a medication is administered to short of ECV.