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Cesarean delivery after successful external cephalic version of breech presentation at term: a comparative study
American Journal of Obstetrics and Gynecology (2004) 190, 763e8
www.elsevier.com/locate/ajog
Cesarean delivery after successful external cephalic version of breech presentation at term: A comparative study Yannik Ve´zina, MD, Emmanuel Bujold, MD, Jocelyne Varin, RN, Ge´rald P. Marquette, MD, Marc Boucher, MD Department of Obstetrics and Gynecology, Hoˆpital Sainte-Justine, Montre´al, Que´bec, Canada Received for publication June 16, 2003; revised September 22, 2003; accepted September 23, 2003
–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– KEY WORDS External cephalic version Breech presentation Cesarean delivery
Objective: The purpose of this study was to evaluate the rate and indications of cesarean delivery after a successful external cephalic version. Study design: A case-control study was performed from patients who were delivered in a tertiary care center between 1987 and 2000. Each patient who underwent a successful external cephalic version (study group) was compared with the next woman with the same parity, who was delivered at term (control group). Nulliparous and multiparous women were analyzed separately. Chi-squared, Mann-Whitney, and Student t tests were used for statistical analysis. Multivariate logistic regression analysis was performed where appropriate. Results: A total of 602 patients were included in this study. The rates of cesarean delivery in nulliparous women (29.8% vs 15.9%; P!.001) and in multiparous women (15.9% vs 4.7%; P!.001) were significantly higher when compared with the control group. Patients with successful external cephalic version were more likely to have a cesarean delivery for dystocia (nulliparous, 22.5% vs 11.9%; P = .01; multiparous, 10.9% vs 1.3%; P!.01). After an adjustment for confounding variables, a successful external cephalic version was associated with an increased rate of cesarean delivery at term (nulliparous: odds ratio, 2.04; 95% CI, 1.13-3.68; multiparous: odds ratio, 4.30; 95% CI, 1.76-10.54). Conclusion: The rate of cesarean delivery for dystocia is increased after a successful trial of external cephalic version in both nulliparous and multiparous women. Ó 2004 Elsevier Inc. All rights reserved.
––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– Recent data suggest that there is an increased risk of neonatal morbidity that is associated with a trial of Presented at the 23rd Annual Meeting of the Society for MaternalFetal Medicine, San Francisco, February 3-8, 2003. Reprint requests: Emmanuel Bujold, MD, Hoˆpital Sainte-Justine, 3175 Coˆte Ste-Catherine, Montreal, Quebec, Canada, H3T 1C5. E-mail: [email protected] 0002-9378/$ - see front matter Ó 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.ajog.2003.09.056
breech vaginal delivery.1 Therefore, increasingly, clinicians are counseling patients who have a fetus in breech presentation at term against a trial of labor.2 Because external cephalic version (ECV) is performed with ultrasound guidance and with appropriate fetal monitoring, it is a safe alternative to routine cesarean delivery and has been demonstrated to reduce the rate of breech presentation at the time of labor.3,4
764 Table I
Ve´zina et al Literature for cesarean delivery after successful ECV Patients with successful ECV and controls
Cesarean rate (cases vs controls)
38 cases 114 controls 92 cases 184 controls 76 cases 76 controls 279 cases 28447 controls
10.5% vs 7.0% P = .5 22.8% vs 23.4% NS 8% vs 6% P = .74 23.3% vs 9.4% OR 3,1 (CI 95% 2.3-4.1)
Laros 1995 (US)7
174 cases no formal control
31% vs 15% P!.05
Lau 1997 (Hong Kong)8
154 cases 308 controls
16.9% vs 7.5% P!.005
Ben Haroush 2002 (Israel)5
96 cases 192 controls
19.8% vs 6.25% P!.001
Wax 2000 (US)
11
Siddiki 1999 (US)10 Egge 1994 (US)9 Chan 2002 (Hong Kong)6
Comments
Higher rate of cesarean for suspected fetal distress and/or failure to progress Higher rate of cesarean for failure to progress and/or failed induction Higher rate of cesarean for labor dystocia and/or suspected fetal distress Higher rate of cesarean for labor dystocia and/or fetal malpresentation
NS, Not significant.
It has been reported that the rate of cesarean delivery is higher in patients with a fetus in cephalic presentation after a successful ECV, when compared with the general population.5-8 However, other studies do not support those results (Table I).9-11 This controversy is most likely the result of the small sample size and/or the heterogeneity of study populations. The purpose of this study was to evaluate whether patients who had undergone successful ECV at term were at a higher risk of cesarean delivery.
Study design This cohort study included patients who were referred to a single institution, Sainte-Justine Hospital, for a trial of ECV between November 1987 and May 2000. The data for this study were collected prospectively as part of an observational study that was performed at our institution. This study was approved by the Research Ethics Review Board. In 1987, a program of ECV was implemented. Two referral clinics were designated to perform ECVs and were staffed by 2 maternal-fetal medicine subspecialists (M.B. and G.P.M.). Pregnant women with a fetus in breech presentation at term were referred by physicians or midwives to these specialized outpatient clinics. The referral population consisted of physicians and midwives who delivered at our own institution and those from the greater Montreal metropolitan area. Inclusion criteria for ECV included a pregnancy with a fetus in breech presentation and a gestational age of
R36 weeks. Exclusion criteria for ECV included multiple gestations, pregnancies with a nonmobile breech, pregnancies complicated by contraindications to a vaginal delivery, major congenital anomalies, patients in labor, or patients with premature rupture of membranes. Data that were recorded included maternal age, parity, gestational age, and information about medical history, pregnancy history, and pregnancy complications. An ultrasound examination was performed to evaluate the type of breech, fetal weight, amniotic fluid index, and localization of the placenta. Fundal height and mobility of the presentation were noted. Breech mobility was defined as the possibility to elevate the fetal presentation from the maternal pelvis through suprapubic pressure. No attempt was made to move the breech presentation by vaginal manipulation. If the patient was eligible for ECV, an informed consent was obtained from the patient. From 1987 to 1994, the standard of care in our institution was to offer intravenous ritodrine (111 mg/min) as tocolytic in ECV if there was no contraindication. Between 1994 and 1996, patients were assigned randomly to receive intravenous ritodrine (111 m/min) or intravenous placebo on the basis of an approved research protocol. After the publication of a study by Marquette et al12 in 1996 that showed a benefit of intravenous ritodrine only in nulliparous women, the use of tocolytic was stopped for multiparous patients, and intravenous ritodrine was used only for nulliparous patients. The technique that was used was either a backward or a forward flip. A maximum of 3 attempts was allowed. A nonstress test was performed before and after the proce-
Ve´zina et al Table II
765
Clinical characteristics of patients after successful ECV in comparison to control group Nulliparous
Maternal age (y) meanGSD* Parity (median [min, max])y Gestational age (wk) (meanGSD)* Birth weight (g) (meanGSD)* Prior cesarean (No. [%])z Induction of labor (No. [%])z Epidural (No. [%])z
Multiparous
Post ECV (n = 151)
Control (n = 151)
P value
Post ECV (n = 150)
Control (n = 150)
P value
28.6G5.0 0 39.9G1.3
28.3G5.5 0 39.4G1.1
NS !.01
32.1G4.7 1 (1,4) 39.4G1.3
30.5G5.4 1 (1,4) 39.4G1.2
.01 NS NS
3408G439
3378G426
NS
3514G477
3498G441
NS
0 21 (14) 110 (73)
0 23 (15) 91 (60)
NS .02
17 (11) 17 (11) 73 (49)
7 (5) 13 (9) 53 (35)
.05 NS .02
NS, Not significant. * Student t test. y Mann-Whitney test. z Pearson c2 test.
dure. Rh immune globulin was administered when indicated. The mode of delivery, the indication for cesarean delivery, gender, birth weight, and Apgar scores were collected by review of medical records. The study group consisted of all patients who had undergone a successful ECV and were admitted for delivery in our institution with a fetus in cephalic presentation. One control patient was selected for each patient in the study group. With the use of the delivery log book of our labor and delivery unit, each study case was matched, according to parity, to the next woman with a singleton gestation at term who had no contraindication to labor and who was delivered in our center. We compared demographic data, the rate of induction of labor, epidural analgesia, operative vaginal delivery, cesarean delivery, and the indications for cesarean delivery between both groups. Nulliparous and multiparous women were analyzed separately. Statistical analysis was performed using chi-squared, Mann-Whitney, and Student t tests, where appropriate. A multivariate analysis was performed to adjust for confounding variables that were associated with cesarean delivery. A probability value of !.05 was considered statistically significant. A power analysis was performed to evaluate the sample size that was required to detect a significant difference in the cesarean delivery rate. When a 10% baseline rate for cesarean delivery (excluding patients undergoing an elective cesarean), an a-error of .05 and a b-error of .20 was considered, we calculated that 220 patients would be required in each group to detect a 100% increase in cesarean delivery rate.
Results From November 1987 to May 2000, of 50,686 patients who were delivered in our center, 655 patients underwent a trial of ECV, of those 326 trials (50%) were
successful. The rate of spontaneous reversion to breech was 7.7% (25/326 patients). Therefore, 301 patients underwent a successful ECV with the fetus remaining in a vertex presentation. These 301 study patients were matched to an equal number of women at term with the same parity and who were delivered in our center. Table II depicts the clinical characteristics of the 2 groups. Nulliparous women with a successful ECV had a higher gestational age and a higher frequency of epidural analgesia. In counterpart, multiparous women with a successful ECV had a higher maternal age and a higher rate of epidural analgesia when compared with the control group. Obstetric outcomes are given in Table III. The overall rate of cesarean delivery (parous and nulliparous) was significantly greater in the study group, when compared with the control group (25.1% [74/301 patients] vs 10.5% [31/301 patients]; P!.001). After dividing groups according to parity, the difference in the cesarean delivery rate remained statistically significant in both nulliparous (29.8% vs 15.9%; P!.001) and multiparous women (20.0% vs 4.7%; P!.001). Both nulliparous and multiparous women with a successful ECV had a higher rate of cesarean delivery for dystocia. Multiparous women with a successful ECV also had a higher rate of cesarean delivery for suspected fetal distress and were more likely to have an operative vaginal delivery. To evaluate factors that are associated with cesarean delivery in patients who had a trial of labor after a successful cephalic version, we compared the clinical characteristics of patients who had a successful vaginal delivery and patients who had a cesarean delivery in the study groups (Table IV). Patients who had a cesarean delivery were older, and the birth weight of the neonate was higher. The interval between ECV and delivery, the amniotic fluid index at the time of ECV, and the induction of labor were not significantly different between the study groups. The mean gestational age and the rate
766 Table III
Ve´zina et al Obstetric outcome Nulliparous
Operative vaginal delivery Birth weight O4000 g Cesarean delivery Reason for cesarean Dystocia Non reassuring heart rate Other indications Apgar score at 5 min !7
Multiparous
Post ECV (n [%])
Control (n [%])
P value*
31 (20.5) 14 (9.3) 44 (29.8)
23 (15.2) 12 (7.9) 24 (15.9)
.29 NS !.001
34 8 3 3
18 (11.9) 6 (4.0) 0 3 (2.0)
.01 NS NS NS
(22.5) (5.3) (2.0) (2.0)
Post ECV (n [%]) 13 (8.7) 26 (17.3) 30 (20.0) 16 13 131 1
(10.7) (8.7) (0.7) (0.7)
Control (n [%])
P value*
4 (2.7) 17 (11.3) 7 (4.7)
.02 NS !.001
2 4 1 1
(1.3) (2.7) (0.7) (0.7)
!.01 .02 NS NS
NS, Not significant * Pearson c2 test.
Table IV
Factors associated with mode of delivery after a successful ECV Nulliparous
Maternal age (y) (meanGSD)* Gestational age (wk) (meanGSD)* Interval ECV delivery (d) (meanGSD)* Birth weight (gr) (meanGSD)* Birth weight O4000 g AFI at the term (cm) (meanGSD)* Induction of labor (n [%])y Epidural (n [%])y
Multiparous
Vaginal (n = 106)
Cesarean (n = 45)
P value
Vaginal (n = 120)
Cesarean (n = 30)
P value
28.0G4.8 39.8G1.3 18G10 3364G396 5 (4.7) 12.8G4.4 12 (11.3) 76 (71.7)
30.0G5.3 40.0G1.3 20G10 3512G518 9 (20.0) 13.3G4.5 9 (20.0) 34 (75.6)
!.01 NS NS .02 .003 NS NS NS
31.5G4.3 39.2G1.2 14G9 3470G473 17 (14.2) 13.4G4.6 14 (11.7) 50 (41.7)
34.7G5.5 40.0G1.2 16G9 3693G457 9 (30.0) 13.8G4.3 3 (10.0) 23 (76.7)
!.01 !.01 NS .02 .04 NS NS .001
ECV, External cephalic version, AFI, Amniotic fluid index, NS, not significant. * Student t test. y Pearson c2 test.
of epidural analgesia were also higher in multiparous women who had a cesarean delivery when compared with multiparous women who had a vaginal delivery. A multivariate logistic regression analysis was performed to adjust for confounding variables that are associated with cesarean delivery (Table V). A history of ECV during the current pregnancy, the induction of labor, and a birth weight of O4000 g were associated with cesarean delivery in nulliparous women, although a history of ECV and the use of epidural analgesia were the factors that were associated with cesarean delivery in multiparous women.
Comment We found that a successful trial of ECV is associated with an increased risk of cesarean delivery in both nulliparous and multiparous women. This difference remains statistically significant in both groups after an adjustment for potential confounding variables. Although our finding that patients with a successful ECVs have a higher rate of cesarean delivery is consistent with
4 previously reported studies,5-8 it contradicts 3 other studies that did not find such a difference in cesarean delivery rates.9-11 These 3 studies had small sample size, and none of the studies had sufficient power to detect a 100% difference in the rate of cesarean delivery, considering a baseline cesarean delivery rate of 10%. The difference in the rate of cesarean delivery was due, in part, to an increase in the rate of cesarean delivery for dystocia in women with a successful ECV. In addition, in the multiparous group, there was an increased rate of cesarean delivery for suspected fetal distress. However, this difference was not associated with a difference in the incidence of 5-minute Apgar scores of !7. Reasons for the increase in labor dystocia in patients with successful ECV remains unclear. We propose 3 hypotheses: first, one may suggest that uterine anomalies or atypical maternal pelvis configuration may cause both an increased risk for fetal breech presentation and a higher risk of dystocia during labor. We do not have data about the rate of uterine abnormalities in our population, but we suspected that it was very low. However, operative reports of patients in the study group who had a cesarean delivery were reviewed, and
Ve´zina et al the surgeons reported no uterine anomalies. Moreover, it has been demonstrated that most patients with a previous cesarean delivery for breech presentation will be delivered vaginally at the next pregnancy.13,14 A second explanation could be that patients who have a successful ECV trial, because of the need to have a mobile fetus, are more likely during labor to have a fetus with an unmolded, unengaged head or a head in an asynclitic position or a combination of those factors. It has also been reported that a closed cervix and an unengaged fetus at the time of ECV were associated with a higher rate of successful ECV.15 Consequently, successful ECV may be associated with an unfavorable cervix later in pregnancy and be associated with higher rates of labor induction and cesarean delivery. However, in our study, there were no differences in the rate of labor induction between both groups. Finally, it is a possibility that patients with successful ECVs have an increased uterine compliance that, in time, may be associated with abnormal uterine contractility. We found that patients who had a cesarean delivery after a successful ECV were more likely to have a higher maternal age, a greater neonatal birth weight, and, for multiparous women, to have had an epidural analgesia. Advanced maternal age16,17 and macrosomia18,19 have been demonstrated to be risk factors for cesarean delivery. However, after adjusting for confounding variables, we found that advanced maternal age was not a significant factor for cesarean delivery in this instance. Because epidural analgesia was not a factor that affects the cesarean delivery rate in a randomized trial,20 we believe that multiparous patients with a successful ECV were more likely to have a longer, dysfunctional labor and therefore to receive epidural analgesia. It is worth mentioning that the time that elapsed between ECV and delivery was not different between patients in the study group who had a cesarean delivery and patients who had a vaginal delivery and could not explain a higher rate of cesarean delivery, as suggested in the study by Ben-Haroush et al.5 When we combined both the study and the control group for the multivariate logistic regression analysis, after adjustments for confounding variables, a successful ECV was the only factor that was associated with cesarean delivery in both nulliparous and multiparous women. In nulliparous women, the induction of labor and birth weight of O4000 g were also independent factors that were associated with cesarean delivery. Both variables have been implied as risk factors for cesarean delivery in earlier studies.17,18,21 The strengths of our study are multiple. First, the same 2 obstetricians performed all of the ECVs in our study, and all deliveries took place in the same labor and delivery unit that was managed by a single obstetrician at a time, which decreases the risk of selection biases. Second, this study constitutes the largest cohort of patients with successful ECVs published (Medline,
767 Table V Multiple logistic regression for factors associated with cesarean delivery
Nulliparous women Prior ECV Induction of labor Maternal age O35 y Epidural use Birth weight O4000 g Gestational age O41 wk Multiparous women Prior ECV Induction of labor Maternal age O35 y Epidural use Birth weight O4000 g Gestational age O41wk Prior cesarean delivery
Odds ratio
95% CI
P value
2.04 2.09 1.41 1.63 2.67 1.54
1.13e3.68 1.01e4.33 0.63e3.15 0.84e3.16 1.10e6.47 0.83e2.88
.02 !.05 NS NS .03 NS
4.30 0.99 1.51 5.98 1.61 2.04 1.42
1.76e10.54 0.29e3.30 0.67e3.36 2.40e14.94 0.63e4.07 0.83e5.02 0.50e4.05
.001 NS NS !.001 NS NS NS
NS, Not significant.
1966-2002. Key words: ‘‘external cephalic version’’). Our sample size had the power to detect a difference of 8% in the absolute rate of cesarean delivery between study groups. Moreover, our study had the power to detect a difference of 12% in the absolute rate of cesarean delivery in both nulliparous and multiparous women when evaluated separately. Finally, adjustment for multiple confounding variables was provided. The main limitation to this study is that the control group was obtained retrospectively, although data for ECV patients had been collected prospectively. In conclusion, although ECV is associated with an increased rate of cesarean delivery when compared with spontaneous vertex controls, the rate of vaginal delivery after successful ECV delivery was 70% for nulliparous and 84% in multiparous women. The reasons for this increase in cesarean delivery remain an unresolved issue at this moment, and further studies will need to address this fact.
Acknowledgments We thank Dr Susan Berman for her assistance in the statistics analysis and in the interpretation of the data.
References 1. Hannah ME, Hannah WJ, Hewson SA, Hodnett ED, Saigal S, Willan AR. Planned cesarean section versus planned vaginal birth for presentation at term: a randomised multicentre trial. Lancet 2000;356:1375-83. 2. Hogle KL, Kilburn L, Hewson S, Gafni A, Wall R, Hannah ME. Impact of the international term breech trial on clinical practice and concerns: a survey of centre collaborators. J Obstet Gynaecol Can 2003;25:14-6.
768 3. Hofmeyr GJ, Kulier R. External cephalic version for breech presentation at term. Cochrane Database Syst Rev 2000;2: CD000083. 4. American College of Obstetricians and Gynecologists. External cephalic version. Washington (DC): The College; 2000 Practice bulletin no.: 13. 5. Ben-Haroush A, Perri T, Bar J, Yogev Y, Bar-Hava I, Hod M, et al. Mode of delivery following successful external cephalic version. Am J Perinatol 2002;19:355-60. 6. Chan LYS, Leung TY, Fok WY, Chan LW, Lau TK. High incidence of obstetrics interventions after successful external cephalic version. BJOG 2002;109:627-31. 7. Laros RK, Flanagan TA, Kilpatrick SJ. Management of term breech presentation: a protocol of external cephalic version and selective trial of labor. Am J Obstet Gynecol 1995;172:1916-25. 8. Lau TK, Lo KWK, Rogers M. Pregnancy outcome after successful external cephalic version for breech presentation at term. Am J Obstet Gynecol 1997;176:218-23. 9. Egge T, Schanberger C, Schaper A. Dysfunctional labor after external cephalic version. Obstet Gynecol 1994;83:771-2. 10. Siddiki D, Stiller RJ, Collins J, Laifer SA. Pregnancy outcome after successful external cephalic version. Am J Obstet Gynecol 1999;181:1092-5. 11. Wax JR, Sutula K, Lerer T, Steinfeld J, Ingardia CJ. Labor and delivery following successful external cephalic version. Am J Perinatol 2000;17:183-6. 12. Marquette GP, Boucher M, Theriault D, Rinfret D. Does the use of a tocolytic agent affect the success rate of external cephalic version? Am J Obstet Gynecol 1996;175:859-61.
Ve´zina et al 13. Wing DA, Paul RH. Vaginal birth after cesarean section: selection and management. Clin Obstet Gynecol 1999;42:836-48. 14. Bujold E, Gauthier RJ. Should we allow a trial of labor after a previous cesarean for dystocia in the second stage of labor? Obstet Gynecol 2001;98:652-5. 15. Newman RB, Peacock BS, VanDorsten JP, Hunt HH. Predicting success of external cephalic version. Am J Obstet Gynecol 1993; 169:245-9. 16. Main DM, Main EK, Moore DH 2nd. The relationship between maternal age and uterine dysfunction: a continuous effect throughout reproductive life. Am J Obstet Gynecol 2000;182: 1312-20. 17. Ecker JL, Chen KT, Cohen AP, Riley LE, Lieberman ES. Increased risk of cesarean delivery with advancing maternal age: indications and associated factors in nulliparous women. Am J Obstet Gynecol 2001;185:883-7. 18. Maslow AS, Sweeny AL. Elective induction of labor as a risk factor for cesarean delivery among low-risk women at term. Obstet Gynecol 2000;95:917-22. 19. Mulik V, Usha Kiran TS, Bethal J, Bhal PS. The outcome of macrosomic fetuses in a low risk primigravid population. Int J Gynaecol Obstet 2003;80:15-22. 20. Sharma SK, Alexander JM, Messick G, Bloom SL, McIntire DD, Wiley J, et al. A randomized trial of epidural analgesia versus intravenous meperidine analgesia during labor in nulliparous women. Anesthesiology 2002;96:546-51. 21. Cammu H, Martens G, Ruyssincks G, Amy JJ. Outcome after elective labor induction in nulliparous women: a matched cohort study. Am J Obstet Gynecol 2002;186:240-4.
www.elsevier.com/locate/ajog
Cesarean delivery after successful external cephalic version of breech presentation at term: A comparative study Yannik Ve´zina, MD, Emmanuel Bujold, MD, Jocelyne Varin, RN, Ge´rald P. Marquette, MD, Marc Boucher, MD Department of Obstetrics and Gynecology, Hoˆpital Sainte-Justine, Montre´al, Que´bec, Canada Received for publication June 16, 2003; revised September 22, 2003; accepted September 23, 2003
–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– KEY WORDS External cephalic version Breech presentation Cesarean delivery
Objective: The purpose of this study was to evaluate the rate and indications of cesarean delivery after a successful external cephalic version. Study design: A case-control study was performed from patients who were delivered in a tertiary care center between 1987 and 2000. Each patient who underwent a successful external cephalic version (study group) was compared with the next woman with the same parity, who was delivered at term (control group). Nulliparous and multiparous women were analyzed separately. Chi-squared, Mann-Whitney, and Student t tests were used for statistical analysis. Multivariate logistic regression analysis was performed where appropriate. Results: A total of 602 patients were included in this study. The rates of cesarean delivery in nulliparous women (29.8% vs 15.9%; P!.001) and in multiparous women (15.9% vs 4.7%; P!.001) were significantly higher when compared with the control group. Patients with successful external cephalic version were more likely to have a cesarean delivery for dystocia (nulliparous, 22.5% vs 11.9%; P = .01; multiparous, 10.9% vs 1.3%; P!.01). After an adjustment for confounding variables, a successful external cephalic version was associated with an increased rate of cesarean delivery at term (nulliparous: odds ratio, 2.04; 95% CI, 1.13-3.68; multiparous: odds ratio, 4.30; 95% CI, 1.76-10.54). Conclusion: The rate of cesarean delivery for dystocia is increased after a successful trial of external cephalic version in both nulliparous and multiparous women. Ó 2004 Elsevier Inc. All rights reserved.
––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– Recent data suggest that there is an increased risk of neonatal morbidity that is associated with a trial of Presented at the 23rd Annual Meeting of the Society for MaternalFetal Medicine, San Francisco, February 3-8, 2003. Reprint requests: Emmanuel Bujold, MD, Hoˆpital Sainte-Justine, 3175 Coˆte Ste-Catherine, Montreal, Quebec, Canada, H3T 1C5. E-mail: [email protected] 0002-9378/$ - see front matter Ó 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.ajog.2003.09.056
breech vaginal delivery.1 Therefore, increasingly, clinicians are counseling patients who have a fetus in breech presentation at term against a trial of labor.2 Because external cephalic version (ECV) is performed with ultrasound guidance and with appropriate fetal monitoring, it is a safe alternative to routine cesarean delivery and has been demonstrated to reduce the rate of breech presentation at the time of labor.3,4
764 Table I
Ve´zina et al Literature for cesarean delivery after successful ECV Patients with successful ECV and controls
Cesarean rate (cases vs controls)
38 cases 114 controls 92 cases 184 controls 76 cases 76 controls 279 cases 28447 controls
10.5% vs 7.0% P = .5 22.8% vs 23.4% NS 8% vs 6% P = .74 23.3% vs 9.4% OR 3,1 (CI 95% 2.3-4.1)
Laros 1995 (US)7
174 cases no formal control
31% vs 15% P!.05
Lau 1997 (Hong Kong)8
154 cases 308 controls
16.9% vs 7.5% P!.005
Ben Haroush 2002 (Israel)5
96 cases 192 controls
19.8% vs 6.25% P!.001
Wax 2000 (US)
11
Siddiki 1999 (US)10 Egge 1994 (US)9 Chan 2002 (Hong Kong)6
Comments
Higher rate of cesarean for suspected fetal distress and/or failure to progress Higher rate of cesarean for failure to progress and/or failed induction Higher rate of cesarean for labor dystocia and/or suspected fetal distress Higher rate of cesarean for labor dystocia and/or fetal malpresentation
NS, Not significant.
It has been reported that the rate of cesarean delivery is higher in patients with a fetus in cephalic presentation after a successful ECV, when compared with the general population.5-8 However, other studies do not support those results (Table I).9-11 This controversy is most likely the result of the small sample size and/or the heterogeneity of study populations. The purpose of this study was to evaluate whether patients who had undergone successful ECV at term were at a higher risk of cesarean delivery.
Study design This cohort study included patients who were referred to a single institution, Sainte-Justine Hospital, for a trial of ECV between November 1987 and May 2000. The data for this study were collected prospectively as part of an observational study that was performed at our institution. This study was approved by the Research Ethics Review Board. In 1987, a program of ECV was implemented. Two referral clinics were designated to perform ECVs and were staffed by 2 maternal-fetal medicine subspecialists (M.B. and G.P.M.). Pregnant women with a fetus in breech presentation at term were referred by physicians or midwives to these specialized outpatient clinics. The referral population consisted of physicians and midwives who delivered at our own institution and those from the greater Montreal metropolitan area. Inclusion criteria for ECV included a pregnancy with a fetus in breech presentation and a gestational age of
R36 weeks. Exclusion criteria for ECV included multiple gestations, pregnancies with a nonmobile breech, pregnancies complicated by contraindications to a vaginal delivery, major congenital anomalies, patients in labor, or patients with premature rupture of membranes. Data that were recorded included maternal age, parity, gestational age, and information about medical history, pregnancy history, and pregnancy complications. An ultrasound examination was performed to evaluate the type of breech, fetal weight, amniotic fluid index, and localization of the placenta. Fundal height and mobility of the presentation were noted. Breech mobility was defined as the possibility to elevate the fetal presentation from the maternal pelvis through suprapubic pressure. No attempt was made to move the breech presentation by vaginal manipulation. If the patient was eligible for ECV, an informed consent was obtained from the patient. From 1987 to 1994, the standard of care in our institution was to offer intravenous ritodrine (111 mg/min) as tocolytic in ECV if there was no contraindication. Between 1994 and 1996, patients were assigned randomly to receive intravenous ritodrine (111 m/min) or intravenous placebo on the basis of an approved research protocol. After the publication of a study by Marquette et al12 in 1996 that showed a benefit of intravenous ritodrine only in nulliparous women, the use of tocolytic was stopped for multiparous patients, and intravenous ritodrine was used only for nulliparous patients. The technique that was used was either a backward or a forward flip. A maximum of 3 attempts was allowed. A nonstress test was performed before and after the proce-
Ve´zina et al Table II
765
Clinical characteristics of patients after successful ECV in comparison to control group Nulliparous
Maternal age (y) meanGSD* Parity (median [min, max])y Gestational age (wk) (meanGSD)* Birth weight (g) (meanGSD)* Prior cesarean (No. [%])z Induction of labor (No. [%])z Epidural (No. [%])z
Multiparous
Post ECV (n = 151)
Control (n = 151)
P value
Post ECV (n = 150)
Control (n = 150)
P value
28.6G5.0 0 39.9G1.3
28.3G5.5 0 39.4G1.1
NS !.01
32.1G4.7 1 (1,4) 39.4G1.3
30.5G5.4 1 (1,4) 39.4G1.2
.01 NS NS
3408G439
3378G426
NS
3514G477
3498G441
NS
0 21 (14) 110 (73)
0 23 (15) 91 (60)
NS .02
17 (11) 17 (11) 73 (49)
7 (5) 13 (9) 53 (35)
.05 NS .02
NS, Not significant. * Student t test. y Mann-Whitney test. z Pearson c2 test.
dure. Rh immune globulin was administered when indicated. The mode of delivery, the indication for cesarean delivery, gender, birth weight, and Apgar scores were collected by review of medical records. The study group consisted of all patients who had undergone a successful ECV and were admitted for delivery in our institution with a fetus in cephalic presentation. One control patient was selected for each patient in the study group. With the use of the delivery log book of our labor and delivery unit, each study case was matched, according to parity, to the next woman with a singleton gestation at term who had no contraindication to labor and who was delivered in our center. We compared demographic data, the rate of induction of labor, epidural analgesia, operative vaginal delivery, cesarean delivery, and the indications for cesarean delivery between both groups. Nulliparous and multiparous women were analyzed separately. Statistical analysis was performed using chi-squared, Mann-Whitney, and Student t tests, where appropriate. A multivariate analysis was performed to adjust for confounding variables that were associated with cesarean delivery. A probability value of !.05 was considered statistically significant. A power analysis was performed to evaluate the sample size that was required to detect a significant difference in the cesarean delivery rate. When a 10% baseline rate for cesarean delivery (excluding patients undergoing an elective cesarean), an a-error of .05 and a b-error of .20 was considered, we calculated that 220 patients would be required in each group to detect a 100% increase in cesarean delivery rate.
Results From November 1987 to May 2000, of 50,686 patients who were delivered in our center, 655 patients underwent a trial of ECV, of those 326 trials (50%) were
successful. The rate of spontaneous reversion to breech was 7.7% (25/326 patients). Therefore, 301 patients underwent a successful ECV with the fetus remaining in a vertex presentation. These 301 study patients were matched to an equal number of women at term with the same parity and who were delivered in our center. Table II depicts the clinical characteristics of the 2 groups. Nulliparous women with a successful ECV had a higher gestational age and a higher frequency of epidural analgesia. In counterpart, multiparous women with a successful ECV had a higher maternal age and a higher rate of epidural analgesia when compared with the control group. Obstetric outcomes are given in Table III. The overall rate of cesarean delivery (parous and nulliparous) was significantly greater in the study group, when compared with the control group (25.1% [74/301 patients] vs 10.5% [31/301 patients]; P!.001). After dividing groups according to parity, the difference in the cesarean delivery rate remained statistically significant in both nulliparous (29.8% vs 15.9%; P!.001) and multiparous women (20.0% vs 4.7%; P!.001). Both nulliparous and multiparous women with a successful ECV had a higher rate of cesarean delivery for dystocia. Multiparous women with a successful ECV also had a higher rate of cesarean delivery for suspected fetal distress and were more likely to have an operative vaginal delivery. To evaluate factors that are associated with cesarean delivery in patients who had a trial of labor after a successful cephalic version, we compared the clinical characteristics of patients who had a successful vaginal delivery and patients who had a cesarean delivery in the study groups (Table IV). Patients who had a cesarean delivery were older, and the birth weight of the neonate was higher. The interval between ECV and delivery, the amniotic fluid index at the time of ECV, and the induction of labor were not significantly different between the study groups. The mean gestational age and the rate
766 Table III
Ve´zina et al Obstetric outcome Nulliparous
Operative vaginal delivery Birth weight O4000 g Cesarean delivery Reason for cesarean Dystocia Non reassuring heart rate Other indications Apgar score at 5 min !7
Multiparous
Post ECV (n [%])
Control (n [%])
P value*
31 (20.5) 14 (9.3) 44 (29.8)
23 (15.2) 12 (7.9) 24 (15.9)
.29 NS !.001
34 8 3 3
18 (11.9) 6 (4.0) 0 3 (2.0)
.01 NS NS NS
(22.5) (5.3) (2.0) (2.0)
Post ECV (n [%]) 13 (8.7) 26 (17.3) 30 (20.0) 16 13 131 1
(10.7) (8.7) (0.7) (0.7)
Control (n [%])
P value*
4 (2.7) 17 (11.3) 7 (4.7)
.02 NS !.001
2 4 1 1
(1.3) (2.7) (0.7) (0.7)
!.01 .02 NS NS
NS, Not significant * Pearson c2 test.
Table IV
Factors associated with mode of delivery after a successful ECV Nulliparous
Maternal age (y) (meanGSD)* Gestational age (wk) (meanGSD)* Interval ECV delivery (d) (meanGSD)* Birth weight (gr) (meanGSD)* Birth weight O4000 g AFI at the term (cm) (meanGSD)* Induction of labor (n [%])y Epidural (n [%])y
Multiparous
Vaginal (n = 106)
Cesarean (n = 45)
P value
Vaginal (n = 120)
Cesarean (n = 30)
P value
28.0G4.8 39.8G1.3 18G10 3364G396 5 (4.7) 12.8G4.4 12 (11.3) 76 (71.7)
30.0G5.3 40.0G1.3 20G10 3512G518 9 (20.0) 13.3G4.5 9 (20.0) 34 (75.6)
!.01 NS NS .02 .003 NS NS NS
31.5G4.3 39.2G1.2 14G9 3470G473 17 (14.2) 13.4G4.6 14 (11.7) 50 (41.7)
34.7G5.5 40.0G1.2 16G9 3693G457 9 (30.0) 13.8G4.3 3 (10.0) 23 (76.7)
!.01 !.01 NS .02 .04 NS NS .001
ECV, External cephalic version, AFI, Amniotic fluid index, NS, not significant. * Student t test. y Pearson c2 test.
of epidural analgesia were also higher in multiparous women who had a cesarean delivery when compared with multiparous women who had a vaginal delivery. A multivariate logistic regression analysis was performed to adjust for confounding variables that are associated with cesarean delivery (Table V). A history of ECV during the current pregnancy, the induction of labor, and a birth weight of O4000 g were associated with cesarean delivery in nulliparous women, although a history of ECV and the use of epidural analgesia were the factors that were associated with cesarean delivery in multiparous women.
Comment We found that a successful trial of ECV is associated with an increased risk of cesarean delivery in both nulliparous and multiparous women. This difference remains statistically significant in both groups after an adjustment for potential confounding variables. Although our finding that patients with a successful ECVs have a higher rate of cesarean delivery is consistent with
4 previously reported studies,5-8 it contradicts 3 other studies that did not find such a difference in cesarean delivery rates.9-11 These 3 studies had small sample size, and none of the studies had sufficient power to detect a 100% difference in the rate of cesarean delivery, considering a baseline cesarean delivery rate of 10%. The difference in the rate of cesarean delivery was due, in part, to an increase in the rate of cesarean delivery for dystocia in women with a successful ECV. In addition, in the multiparous group, there was an increased rate of cesarean delivery for suspected fetal distress. However, this difference was not associated with a difference in the incidence of 5-minute Apgar scores of !7. Reasons for the increase in labor dystocia in patients with successful ECV remains unclear. We propose 3 hypotheses: first, one may suggest that uterine anomalies or atypical maternal pelvis configuration may cause both an increased risk for fetal breech presentation and a higher risk of dystocia during labor. We do not have data about the rate of uterine abnormalities in our population, but we suspected that it was very low. However, operative reports of patients in the study group who had a cesarean delivery were reviewed, and
Ve´zina et al the surgeons reported no uterine anomalies. Moreover, it has been demonstrated that most patients with a previous cesarean delivery for breech presentation will be delivered vaginally at the next pregnancy.13,14 A second explanation could be that patients who have a successful ECV trial, because of the need to have a mobile fetus, are more likely during labor to have a fetus with an unmolded, unengaged head or a head in an asynclitic position or a combination of those factors. It has also been reported that a closed cervix and an unengaged fetus at the time of ECV were associated with a higher rate of successful ECV.15 Consequently, successful ECV may be associated with an unfavorable cervix later in pregnancy and be associated with higher rates of labor induction and cesarean delivery. However, in our study, there were no differences in the rate of labor induction between both groups. Finally, it is a possibility that patients with successful ECVs have an increased uterine compliance that, in time, may be associated with abnormal uterine contractility. We found that patients who had a cesarean delivery after a successful ECV were more likely to have a higher maternal age, a greater neonatal birth weight, and, for multiparous women, to have had an epidural analgesia. Advanced maternal age16,17 and macrosomia18,19 have been demonstrated to be risk factors for cesarean delivery. However, after adjusting for confounding variables, we found that advanced maternal age was not a significant factor for cesarean delivery in this instance. Because epidural analgesia was not a factor that affects the cesarean delivery rate in a randomized trial,20 we believe that multiparous patients with a successful ECV were more likely to have a longer, dysfunctional labor and therefore to receive epidural analgesia. It is worth mentioning that the time that elapsed between ECV and delivery was not different between patients in the study group who had a cesarean delivery and patients who had a vaginal delivery and could not explain a higher rate of cesarean delivery, as suggested in the study by Ben-Haroush et al.5 When we combined both the study and the control group for the multivariate logistic regression analysis, after adjustments for confounding variables, a successful ECV was the only factor that was associated with cesarean delivery in both nulliparous and multiparous women. In nulliparous women, the induction of labor and birth weight of O4000 g were also independent factors that were associated with cesarean delivery. Both variables have been implied as risk factors for cesarean delivery in earlier studies.17,18,21 The strengths of our study are multiple. First, the same 2 obstetricians performed all of the ECVs in our study, and all deliveries took place in the same labor and delivery unit that was managed by a single obstetrician at a time, which decreases the risk of selection biases. Second, this study constitutes the largest cohort of patients with successful ECVs published (Medline,
767 Table V Multiple logistic regression for factors associated with cesarean delivery
Nulliparous women Prior ECV Induction of labor Maternal age O35 y Epidural use Birth weight O4000 g Gestational age O41 wk Multiparous women Prior ECV Induction of labor Maternal age O35 y Epidural use Birth weight O4000 g Gestational age O41wk Prior cesarean delivery
Odds ratio
95% CI
P value
2.04 2.09 1.41 1.63 2.67 1.54
1.13e3.68 1.01e4.33 0.63e3.15 0.84e3.16 1.10e6.47 0.83e2.88
.02 !.05 NS NS .03 NS
4.30 0.99 1.51 5.98 1.61 2.04 1.42
1.76e10.54 0.29e3.30 0.67e3.36 2.40e14.94 0.63e4.07 0.83e5.02 0.50e4.05
.001 NS NS !.001 NS NS NS
NS, Not significant.
1966-2002. Key words: ‘‘external cephalic version’’). Our sample size had the power to detect a difference of 8% in the absolute rate of cesarean delivery between study groups. Moreover, our study had the power to detect a difference of 12% in the absolute rate of cesarean delivery in both nulliparous and multiparous women when evaluated separately. Finally, adjustment for multiple confounding variables was provided. The main limitation to this study is that the control group was obtained retrospectively, although data for ECV patients had been collected prospectively. In conclusion, although ECV is associated with an increased rate of cesarean delivery when compared with spontaneous vertex controls, the rate of vaginal delivery after successful ECV delivery was 70% for nulliparous and 84% in multiparous women. The reasons for this increase in cesarean delivery remain an unresolved issue at this moment, and further studies will need to address this fact.
Acknowledgments We thank Dr Susan Berman for her assistance in the statistics analysis and in the interpretation of the data.
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