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Anesthesia-facilitated external cephalic version: pennywise or pound-foolish?

2012; Springer Science+Business Media; Volume: 60; Issue: 1 Linguagem: Inglês

10.1007/s12630-012-9817-2

1496-8975

Roanne Preston, Robert Jee,

Assisted Reproductive Technology and Twin Pregnancy

External cephalic version (ECV) has likely been around for centuries as obstetricians (and midwives) sought to avoid the known dangers of a vaginal breech birth. Perhaps to the surprise of many anesthesiologists, the same issue applies to anesthesia assistance for ECV, as maternal pain is one of the two most common reasons to abort attempted ECV. In 1968, Ellis reported on 314 cases of attempted ECV under general anesthesia. At the time, the perinatal mortality from vaginal breech birth was 8-10%. There were 262 successful versions with a perinatal mortality of just less than 1%, and ‘‘none of the mothers died or suffered significant harm’’. Anesthesia for the procedure typically consisted of chloroform or ether and sometimes a muscle relaxant. In 2000, the Term Breech Trial, a multinational randomized controlled trial of vaginal vs elective Cesarean delivery for breech presentation at term, published results for 2,088 women that showed significant excess perinatal mortality in the vaginal delivery group (relative risk [RR] 0.33, 95% confidence interval [CI] 0.19 to 0.56). This led to an abrupt change in practice in developed countries, as almost all term breech presentations were then booked for elective Cesarean delivery. Subsequently, the trial has received significant criticism, leading to reconsideration of the options available to women presenting close to term with a fetus in breech position. The American College of Obstetricians and Gynecologists and the Society of Obstetricians and Gynecologists of Canada published new guidelines for breech vaginal birth in 2006 and 2009, respectively. The guidelines essentially endorsed a return to a practice condemned for its high perinatal mortality, but with strict provisos for women’s eligibility. Unfortunately, obstetrical expertise in performing a safe vaginal breech birth had faded away in the interim, and that, combined with a concerted effort to reduce the escalating Cesarean delivery rate, has led to a resurgence in interest in ECV and anesthesia-facilitated ECV. External cephalic version is typically performed at 36-37 weeks’ gestation. Prerequisites include adequate amniotic fluid volume, estimated fetal weight\4,000 g, an appropriate breech configuration (frank or complete), and a willing fully informed woman who has given her consent. The reported success rates vary from 30-70% and are highly dependent on the skill of the operator. Rather than considering medical problems up until time of delivery, the reported complications tend to be only those immediately associated with the procedure; therefore, the true risks associated with ECV may be underestimated. Reports most often describe non-recovering fetal bradycardia resulting in stat Cesarean delivery (1-5 per 1,000 attempted ECVs), placental abruption ( 0.3%), and maternal pain necessitating termination of the procedure (10-45%). Since 1994, there have been several articles examining the use of regional anesthesia to facilitate ECV, specifically, eight randomized controlled trials (two of which remain unpublished), six non-randomized studies, several reviews, and three meta-analyses. From an anesthetic perspective, it has been properly concluded that regional anesthesia (spinal, epidural, or the combination), not just Author contributions Roanne Preston and Robert Jee conceived, wrote, and edited the manuscript.