Weiniger, Carolyn F. MB, ChB1; Ginosar, Yehuda MBBS1; Elchalal, Uriel MD2; Sharon, Einav MD3; Nokrian, Malka RN, MN2; Ezra, Yossef MD2
The breech-presenting fetus at term should be delivered by cesarean according to guidelines published by the American College of Obstetricians and Gynecologists (ACOG) and Royal College of Obstetricians and Gynaecologists because this delivery mode reduces fetal morbidity.1–3 However, overall maternal and fetal morbidity is lower with vaginal delivery.4–5 Normal vaginal delivery is possible after successful external cephalic version to convert the fetus to cephalic presentation. Higher parity is a known predictor of external cephalic version success,6,7 and whereas the success rate for multiparas may be as high as 100%, the success rate of external cephalic version among nulliparas is lower (30–63%).7–10
The Cochrane Database11 and a meta-analysis12 examined randomized controlled trials comparing neuraxial analgesia before performing external cephalic version with no analgesia (control). They both found discordance between trials using neuraxial analgesia for external cephalic version procedures. Those studies that used spinal analgesia (Delisle MF, Kamani AA, Douglas MJ, Bebbington MW. Antepartum external cephalic version under spinal anesthesia: a randomized controlled study [abstract]. J Obstet Gynaecol Can 2003;25:S13)13 reported lower success rates than those with epidural analgesia.14,15 However, the spinal dose was an analgesic dose, as opposed to the anesthetic epidural dose. The study participants in these trials were a heterogeneous population of multiparous and nulliparous women. The success rate of spinal analgesia according to parity was not reported, but in one nonrandomized trial, the success rate of external cephalic version after neuraxial analgesia among nulliparas was 83%.16 The importance of successful external cephalic version for the nullipara is the ability to potentially avoid a uterine scar if external cephalic version is successful. After a cesarean delivery, if external cephalic version fails, there is an almost 91% chance of a subsequent cesarean delivery.17
MATERIALS AND METHODS
This prospective randomized controlled trial was performed in a tertiary referral center in the Post Anesthesia Care Unit of a Labor and Delivery suite with 5,000 deliveries per year. After institutional review board approval (495-29.10.04) from the Hadassah Hebrew University Medical Center, all eligible nulliparous women who requested external cephalic version after 37 weeks of gestation during the period from September 2002 to May 2006 were approached for recruitment before the external cephalic version procedure. Women with a breech-presenting fetus who requested elective cesarean delivery, either after failed external cephalic version at another institution or because they did not wish to try external cephalic version at all, were not included or followed up, and data regarding these women were not collected. Written informed consent was obtained before enrollment to the study. Spinal analgesia was not offered routinely to women for external cephalic version before or during the study period. Patients who refused to participate in the study were not offered spinal analgesia during their external cephalic version procedure, even in cases of pain or failure, so that women could not decide themselves to self-select to spinal analgesia without undergoing study randomization. This was done to avoid selection bias during the study period, such that women who were apprehensive of the external cephalic version, for example due to a low pain tolerance, could not refuse to enroll, receive spinal analgesia, and thus not be represented in the study population.
Study allocation was by sequentially numbered sealed envelopes containing a concealed allocation card designating the patient either to receive (group S), or not receive (group N) spinal analgesia. The allocation cards were randomly inserted into the sequential envelopes by a physician not involved in study enrollment (S.E.). The allocation sequence was concealed until after enrollment, and informed consent was obtained before revealing the study assignment of the participant. Thus, participant demographics would be expected to be similar in each group. Eligible women were enrolled and the allocation revealed either by an anesthetist (C.F.W.) or obstetrician (Y.E.). Concurrently, multiparous women were enrolled according to the similar trial protocol, but the enrollment of 70 women is not complete, and the results will be published at the study completion.
The two obstetricians (Y.E. and U.E.) experienced in performing external cephalic version were nonblinded so that the pressure exerted on the stomach should not be dangerously forceful when spinal analgesia was performed since the patient feedback was removed. In addition, it was likely that the obstetrician would be aware of the study allocation due to the patients’ muted response to the external cephalic version pressure on the abdomen when spinal analgesia had been performed.
Data were obtained from personal interviews before the performance of the external cephalic version procedure, from ultrasonography, and from the senior obstetrician (Y.E. or U.E.) performing the external cephalic version procedure. After delivery, data were retrieved from computer files and telephone interviews.
Inclusion criteria included American Society of Anesthetists status I–II, at 37–40 weeks of gestation, and no fetal abnormality. Women with any of the following were excluded: previous uterine surgery or uterine anomaly, contraindication for vaginal delivery, contraindications for regional analgesia, patient refusal of regional analgesia, neuropathy, and severe back pain with neurological radiation, poor communication, and morbid obesity (body mass index more than 40 kg/m2).
Initially the study protocol called for an intravenous infusion of ritodrine 50 mg intravenously over 30 minutes before performing the external cephalic version procedure for uterine relaxation. However, ritodrine was unavailable after April 2003. After an approved amendment from the institutional review board, a substitution of nifedipine 20 mg sublingually was incorporated into the study protocol.11 Patients were reclining in the left lateral position and underwent continuous noninvasive blood pressure and fetal heart rate monitoring, once administered.
After randomization, the spinal analgesia group (S) received 1,000 mL of Ringer’s lactate solution. In the sitting position, single-shot spinal analgesia was performed with a pencil-point needle. The bupivacaine dose was a surgical analgesia dose of 7.5 mg plain bupivacaine (AstraZeneca [Tec-O-Pharm-Libra Ltd.], Jerusalem, Israel) and was injected intrathecally at L3–4 or L4–5. The patient then reclined in a left lateral tilt, and her position adjusted to encourage spread of the drug to the sensory level of T6. Once analgesia was attained, the procedure of external cephalic version was performed. In cases where a level below T6 was attained, the procedure was performed after 30 minutes from injection of the spinal drug. The senior obstetrician (Y.E. or U.E.) had over 5 years experience with the external cephalic version and was assisted by another obstetrician, and ultrasound surveillance was used. External cephalic version was halted if any of the following occurred: successful conversion, maternal request (indicative of pain), fetal bradycardia, or placental abruption.
The control group (N) assigned to receive no analgesia also received 1,000 mL Ringer’s lactate before the external cephalic version. These women were monitored as for the spinal group and external cephalic version performed as described. Each woman was aware before consenting to study recruitment that crossover from the control group was permitted in the case that minimal effort was exerted on the abdomen, and the patient felt subjective extreme pain which provoked voluntary guarding of the abdominal wall. In this case the woman was subsequently provided with spinal analgesia as described previously, but the attempt was noted as a failure for the study analysis. It was routine procedure in our department during and preceding the study period not to offer spinal (or other) analgesia to women presenting for external cephalic version. For those participating in the study, spinal analgesia was a potential benefit for those randomized to receive it. Women from the control group (N) who were considered by the obstetrician to have had a reasonable attempt of external cephalic version were not offered spinal analgesia even if the procedure was unsuccessful and the fetus remained in a breech presentation.
Sample size considerations were based on previous reporting of a 30% success rate of external cephalic version among nulliparous women in our department.8 Inclusion of at least 35 women in each group allowed a statistical test to have a power of 80% with a one-sided 5% significance level to detect a twofold increase in the success rate of external cephalic version between the two groups.
The primary end point was successful conversion of a breech to a vertex presentation. This was ascertained by ultrasonography and confirmed by both of the two obstetricians performing the external cephalic version. Secondary end points included pain score during procedure (visual analog scale 0=no pain, 10=severe pain), complications associated with external cephalic version or with analgesia (maternal hypotension [greater than 20-mm Hg reduction in systolic blood pressure]), postdural puncture headache, failure of analgesia). In addition, the occurrence of an inability to perform the procedure due to maternal distress or discomfort was recorded, along with the reason for halting the procedure (successful external cephalic version, fetal bradycardia, maternal discomfort).
The statistical analysis was performed with SPSS 14.0 (SPSS Inc, Chicago, IL). The groups were masked during data insertion, and the data were not analyzed before the study completion. The results were analyzed on an intention-to-treat basis, comparing women randomized to receive spinal or no analgesia. Quantitative variables were compared between the two study groups using the independent samples t test and are presented as means and standard deviations. Categorical data were compared between the study groups using the χ2 test or Fisher exact test and are presented as percentages. As a secondary analysis, a logistic regression model was applied to adjust for covariates deemed important according to previous reports. Adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were derived from the logistic regression model. A P value of 5% or less was considered statistically significant.
During the study period, 127 nulliparous women underwent external cephalic version at our institution. The rate of breech presentation among all deliveries was consistently 3.7% in our institution during the study period. Seventy-four women requesting external cephalic version consented to enroll in the study, and four were subsequently excluded (Fig. 1). Therefore, 70 women were analyzed in the study. The allocation of randomization is described in Figure 1. The external cephalic version success rate during the study period was 41.5% among the 53 nulliparous patients who did not enroll in the study. Table 1 demonstrates the population description, and the groups were compared for differences that might influence the outcome despite the assumption due to randomization that there are no differences. There was, in fact, a significant, but nonclinically relevant, difference in the ages of the women (24.6±3.8 compared with 28.1±4.1 years for groups S and N, respectively, P<.001), which occurred by chance. In the spinal group, the median age was 24; four women were under 21 years, and only two were over 30, as opposed to a median of 28, with 10 women over the age of 30 and only one under 21 in the control group. Univariable analysis did not demonstrate a difference between the groups for age and the effect on the success of external cephalic version, P=.079 (OR 0.9, 95% CI 0.8–1.0).
The first 13 women enrolled received ritodrine, and 57 women received nifedipine as an adjuvant uterine relaxant. The success rate of the external cephalic version procedure with spinal analgesia was 4 of 6 (66.7%) when ritodrine was given, compared with 20 of 30 (66.7%) when nifedipine was given. There were no differences between these drugs with regard to uterine tone, ease of palpating the fetal head, incidence of fetal bradycardia, or maternal hypotension.
The external cephalic version procedure was significantly more successful among women who were randomized to receive spinal analgesia (24 of 36 [66.7%] compared with 11 of 34 [32.4%], P=.004) (95% CI of the difference 0.0954 to 0.5513) (Table 2). The number of external cephalic version procedures that were successful on the first attempt was similar in the spinal group: 21 (88%) and 10 (91%) in the control group. Fifteen women in the control group had unsuccessful external cephalic version due to pain that did not allow a sufficient external cephalic version attempt, and all 15 were offered subsequent spinal analgesia. Eight women in the control group who had unsuccessful external cephalic version were not offered spinal analgesia. This postspinal attempt in the control group was considered a failure of external cephalic version for the primary main outcome analysis. Eleven of the fifteen (73%) women who crossed over from the nonanalgesia group had successful external cephalic version with the subsequent spinal analgesia.
A univariable logistic model was used to test whether the statistical imbalance in mean age between the study groups had an effect on the success parameter. In addition, as a secondary analysis, a multivariable logistic model was used to model parameters that were considered important based on previous studies along with study group. Administration of spinal analgesia, placental position, and fetal position were entered as categorical variables. The values of estimated fetal weight6 and body weight6,18 were categorized and entered into the logistic regression model as categorical variables. Gestational age correlated well with estimated fetal weight (R2=.333, P=.006) and was excluded from the model. The level of spinal blockade and relaxation of uterine tone both correlated well with the presence of spinal analgesia (P<.001). Because they were both considered clinically to indicate the same thing, namely presence of analgesia, they were excluded from the final model. The secondary analysis demonstrated that the odds of external cephalic version success was 4.0-fold higher when performed with spinal analgesia, P=.02 (95% CI odds ratio 1.2–12.9).
Maternal age was found to have no statistically significant effect on success of the external cephalic version procedure (OR 0.9, 95% CI 0.8–1.0).
Two independent variables were predictive of success during the external cephalic version procedure, as presented in Table 3. The odds for success in external cephalic version were 8.2-fold higher (95% CI for OR 2.2–30.3) if the fetus was in a complete, rather than a frank, breech position before the external cephalic version attempt (P=.001), and 4.0-fold higher (95% CI for OR 1.2–12.9) if the attempt was performed with spinal analgesia (P=.02). Fetal weight (P=.505) and maternal weight (P=.335) were not statistically significant predictors of success in this study.
There were no cases of placental abruption, fetal distress, or immediate unplanned cesarean delivery. There were two cases of transient fetal heart rate deceleration (up to 2 minutes), which resulted in the external cephalic version being abandoned unsuccessfully. Maternal hypotension occurred in seven cases after the spinal analgesia and in none in the control group, and in all cases this resolved within a few minutes with boluses of ephedrine (10–25 mg) and 200 mL fluid boluses. Two cases of postdural puncture headache were seen, and one required epidural blood patch 2 days after the procedure.
This prospective randomized controlled trial demonstrated that the success rate of external cephalic version among nulliparous women with a breech-presenting fetus at term is increased twofold by the administration of spinal analgesia before the external cephalic version. Cesarean delivery is the delivery mode for almost 90% of women delivering a breech baby in developed countries today.1 The cesarean rate for breech presentation fetuses can be lowered by performing external cephalic version, and this has both health and cost benefits.19 However, the majority of women are not offered or not prepared to choose external cephalic version, citing pain, the failure rate, or concern for complications.20,21 The increased chance of success among nullipara, from 32% to 67%, when spinal analgesia is administered, coupled with the prospect of painless external cephalic version, may encourage nulliparas with breech-presenting babies at term to undergo external cephalic version. After successful external cephalic version, the nulliparous patient has a high chance of a normal delivery,18 which also reduces the likelihood of cesarean delivery in subsequent pregnancies.19 In addition to the advantages of external cephalic version for delivery mode, the current study supports external cephalic version as a minimal-risk procedure.22
Neuraxial analgesia was shown previously to increase the success rate of external cephalic version from approximately 30% to 41–80% in a heterogeneous population of nulliparas and multiparas.12,23 Furthermore, two studies provided surgical doses of epidural analgesia to sensory levels T614 and T1015 and had rates of success that were comparable to that of the current study. Almost half of the cases receiving dense epidural analgesia in these studies were multiparas,14,15 yet their success rate was no higher than that seen in the current study of nulliparas. This suggests that spinal analgesia administered in our nulliparous population may improve the chances of external cephalic version success even more than epidural analgesia by providing optimum conditions for external cephalic version procedure with maximum muscle relaxation.16
The spinal dose used in the current study may be considered excessive for a short and well-tolerated procedure such as external cephalic version although lower pain scores were previously associated with an increased success rate of external cephalic version.24 The effective sensory level reached in the current study was no higher than that seen in previous studies.14,15 A meta-analysis combining four prospective randomized studies measuring the success rate of external cephalic version performed under neuraxial analgesia described an overall success rate of only 50% (Delisle et al, abstract).13–15 This meta-analysis included two studies administering a lower dose of spinal analgesia than that used in the current study, with lower success rate (41–44%) (Delisle et al, abstract).13 Among current study patients, five were randomized to receive spinal analgesia, which they subjectively considered to be inadequate, such that they described the procedure as painful. We checked the success rate of all patients, who either did not receive spinal analgesia or complained of pain during the procedure despite spinal analgesia, and found a significantly higher success rate among those who had adequate analgesia (P=.009).
The study design was limited by permitting some control group women to subsequently receive spinal analgesia in cases when the external cephalic version provoked guarding and tensing of the abdominal wall due to pain, which resulted in inability to manipulate the fetus. This may potentially have limited the external cephalic version attempt made by the obstetrician if the patient showed resistance to the procedure since he could try again under spinal analgesia. However, both obstetricians were very experienced in performing external cephalic version for patients without spinal analgesia, and the spinal analgesia was not offered to all control group patients whose external cephalic version attempt failed. The possibility for subsequent spinal analgesia was offered to control group patients due to the informed consent they were required to receive. Women were informed of the study hypothesis that spinal analgesia may increase the success rate of the external cephalic version. In addition women were informed that the spinal would provide pain relief as an added benefit for those who were randomized to receive spinal analgesia. Following this consent explanation, patients may not have agreed to enroll if their external cephalic version attempt could have been unsuccessful due to extreme pain after randomization to the nonanalgesia control group. After all, they had agreed to potential randomization to receive spinal analgesia, so the crossover was offered as a benefit to encourage study enrollment. Among control group patients who subsequently received spinal analgesia, a high rate of successful external cephalic version was seen once spinal analgesia was provided. A previous nonrandomized study demonstrated an increased success rate of external cephalic version using neuraxial analgesia after failure of the external cephalic version without spinal analgesia,16 and this was attributed both to abdominal wall relaxation, the increased patient comfort, and more concerted effort possible by the obstetrician in the presence of analgesia. Women who felt that spinal analgesia was unnecessary self-selected themselves not to enroll in the study. This may account for the higher success rate (41.5%) among those nulliparous women who were not enrolled in the study than was seen in the control group (30%). A similar low success rate among control group patients was seen in previous randomized controlled trials.14,15 Randomization can only occur among the consenting subgroup of patients undergoing external cephalic version.
The experienced obstetrician was nonblinded, and this is a potential bias seen also in other studies where analgesia was used.12 A pressure monitor is described, which may allow the obstetrician to use appropriate force on the patient’s abdomen when she is anesthetized and cannot signify discomfort.25 However, our obstetrician was always aware of the randomization due to the patient’s comfort during the procedure when anesthesia has been performed, even when not informed of the randomization allocation.
The two groups were not similar in age as may happen in a small randomized study,26 which may have affected the success of the external cephalic version if the older women who were randomized to not receive spinal analgesia were less tolerant to pain. It should be noted that age is not a factor that might be expected to affect the outcome of external cephalic version, as opposed to estimated fetal weight, maternal weight, and gestational age, which were almost identical in both groups.
Introduction of a new replacement tocolytic was considered essential when ritodrine became unavailable because tocolytics have been shown to increase the success of external cephalic version.11 One tocolytic may have been more beneficial in performing successful external cephalic version, although the success rate in this study was identical between spinal and control patients regardless of the tocolytic used.
The incidence of complications was reported despite the fact that the number of patients evaluated was too small to detect major adverse outcomes among women undergoing external cephalic version procedures. Our rate of maternal hypotension after spinal analgesia was low, as previously reported.13 If external cephalic version with spinal analgesia is to be used as a routine option to convert breech presenting fetuses to vertex presentation, further work should examine potential adverse outcomes in a larger population.
This study excluded nulliparas with morbid obesity and low amniotic fluid index, both of which reduce the success rates of external cephalic version,6,18,27 and the study findings should be validated among this population. In summary, spinal analgesia significantly increases the chance of successful external cephalic version in nulliparas, with no additive risk. An increase in the external cephalic version success rate may have limited impact on the overall cesarean delivery rate, but the individual nulliparous patient will benefit greatly. Successful external cephalic version among nulliparas allows possible normal vaginal delivery, which both decreases maternal morbidity and facilitates a higher chance of normal delivery in subsequent pregnancies. The study demonstrates that spinal analgesia for external cephalic version is an important clinical tool that should be considered when planning health services and advice for nulliparous women with a breech presenting fetus.
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