http://informahealthcare.com/jmf ISSN: 1476-7058 (print), 1476-4954 (electronic) J Matern Fetal Neonatal Med, 2014; 27(17): 1805–1808 ! 2014 Informa UK Ltd. DOI: 10.3109/14767058.2014.880880
ORIGINAL ARTICLE
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Which is the safer method of labor induction for oligohydramnios women? Transcervical double balloon catheter or dinoprostone vaginal insert WenYan Wang1, Jianlan Zheng1,2, JingLi Fu1, XiaoQiong Zhang1, QinLing Ma1, ShuiLan Yu1, MeiYing Li3, and Li Hou3 1
Department of Obstetric, The People’s Liberation Army 174th Hospital, Xiamen, China, 2Medical College, Xiamen University, Xiang’an, Xiamen, China, and 3People’s Liberation Army 174th Clinical College, Anhui Medical University, Ximen, China
Abstract
Keywords
Objective: To compare the effectiveness and safety of two cervical ripening methods in term primiparous women with unfavorable cervices and oligohydramnios. Methods: Women (126 cases) with oligohydramnios [amniotic fluid index (AFI) 5 cm] and a low Bishop Score (6) were assigned randomly to use double balloon catheter (mechanical method group, 67 cases) or dinoprostone 10 mg controlled-release vaginal insert (pharmacological method group, 59 cases) for induction of labor. The study’s primary outcome was caesarean section rate (CSR). The secondary outcome measures included maternal and neonatal morbidity, an incremental changes in Bishop Score, and intrapartum interventions. Results: There was no significant difference between the mechanical method group and the pharmacological method group in CSR and change in Bishop Score. Tacysystole, non-reassuring fetal heart patterns, and cases of newborn umbilical-cord arterial blood pH57.1 were significantly lower with the mechanical method compared with the pharmacological method (p50.05). More patients needed additional intervention in the mechanical method group. Conclusions: Both methods resulted in a similar CSR. Double balloon catheter resulted in fewer labor complications, but more frequent use of oxytocin and amniotomy. Compared with dinoprostone vaginal insert, double balloon catheter use may be less problematic in women with oligohydramnios.
Cervical ripening, double balloon catheter, dinoprostone vaginal insert, induction of labor, oligohydramnios
Introduction Cervical assessment is recognized as having a significant impact on successful labor induction for more than 40 years [1]. Induction of labor is an increasingly common obstetric intervention. Successful induction in the patient with an unfavorable cervix is a frequent challenge that obstetricians face. In China, the issue of unsuccessful induction is a particular problem. China’s overall CSR is 46.2% and the CSR without medical indication occurs in 11.7% [2] of cases. There is a large body of research directed at comparing pharmacologic agents or mechanical devices in an effort to identify the best methods of cervical ripening. Prostaglandin cervical ripening in the form of a dinoprostone 10 mg controlled-release vaginal insert as the pharmacologic method has gained widespread use in clinical practice. This method has never been studied in patients with oligohydramnios, where there is an increase chance of non-reassuring fetal heart rate abnormalities during labor [3]. Furthermore, Address for correspondence: Jianlan Zheng, Department of Obstetric, The People’s Liberation Army 174th Hospital, OB, 96 Wenyuan Road, Xiamen 361003, China. E-mail: [email protected]
History Received 12 November 2013 Revised 30 December 2013 Accepted 5 January 2014 Published online 3 February 2014
oligohydramnios is often a medical indication for induction of labor. Mechanical balloon cervical ripening is another option that is used to initiate induction of labor in patient with an unfavorable cervix. Effectiveness of cervical balloon ripening has been debated [4–6]. In the present study, we analyzed the pregnancy outcomes and success of induction through the use of dinoprostone 10 mg controlled-release vaginal insert or double balloon catheter in women with oligohydramnios.
Materials and methods Between April 2010 and February 2011, 132 term primiparous women with oligohydramnios were assessed for eligibility in this study. The investigation was conducted in the Obstetrics Department of The People’s Liberation Army 174th Hospital, Xiamen, China. Oligohydramnios was defined as an amniotic fluid index (AFI) 5 cm [7]. AFI was reconfirmed by one of the investigators prior to randomization. Other inclusion criteria were gestational age beyond 37 0/7 weeks’, singleton pregnancy, vertex presentation, Bishop Score 6, intact membranes, the absence of documented uterine contractions, the absence of prior
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J Matern Fetal Neonatal Med, 2014; 27(17): 1805–1808
C-section delivery history, and reassuring antenatal fetal testing (non-stress test, NST) active, and oxytocin challenge test (OCT) negative upon study entry. Women with antepartum bleeding, chorioamnionitis, placenta previa, or any other contraindication to vaginal delivery were excluded. Patients with a documented prostaglandin allergy, maternal asthma history, vaginitis or cervicitis at presentation, and/or glaucoma history were not eligible for the pharmacological treatment arm. This study protocol was approved and reviewed by the Institutional Ethics Committee of The People’s Liberation Army 174th Hospital, China. After written informed consent was obtained, and assessment of fetal condition and Bishop Score, women were randomly allocated to induction with either mechanical method or pharmacological method (sealed envelope randomization) (Table 1). In the mechanical method group, a double balloon catheter, the cervical ripening balloon (CRB) [Cook Medical Incorporated] was used. The CRB was inserted through the endocervical canal with both balloons ultimately filled with 80 mL of sterile 0.9% NaCl after seating the uterine balloon at the internal os and the vaginal balloon at the external os. The external end of the catheter was taped without traction to the patient’s thigh. Catheter placement was limited to a maximum of 12 h. Catheter removal occurred earlier upon rupture of amniotic membranes or when spontaneously expelled in active labor. In the pharmacological method group, the dinoprostone 10 mg controlled-release vaginal insert [Controlled Therapeutics (Scotland) Limited, East Kilbride, Scotland] was inserted into the subject’s posterior vaginal fornix. Prostaglandin insert removal occurred after 24 h of exposure. Prostaglandin was removed earlier in the presence of active labor or non-reassuring fetal heart rate monitoring. Both groups were monitored for uterine activity and fetal heart rate for at least 0.5 h after the catheter or pharmacologic agent was placed. Subjects were then allowed to ambulate, with periodic heart rate monitoring every 2–4 h. Oxytocin was used after 24 h of unsuccessful ripening, with a 30-min delay between device or medication removal and initiation of oxytocin. Oxytocin was also used for augmentation in active labor for the management of arrest disorders. Two patients needed replacement of their balloon catheter and one needed replacement of prostaglandin insert. All the outcome data were obtained concurrently and recorded by the research team. Statistical analysis of outcomes data was performed with the SPSS for Windows (SPSS version 13.0, SPSS Inc., Chicago, IL) statistical package. Continuous variables were expressed as mean ± SD and compared using t-test and discrete data
with chi-squared test or Fisher’s exact test. A p value of50.05 was established as the level of significance.
Results Six of the 132 primiparous women with oligohydramnios and unfavorable cervix declined to join the study, and declined either of the two methods. All these six patients chose cesarean delivery without induction of labor. One hundred twenty-six subjects were randomized between the two methods. Two patients who were allocated to the mechanical method group were reassigned to the pharmacological method group (one because of catheter insertion failure and one refused catheter placement). Three patients, who were allocated to the pharmacological method group, were reassigned to the mechanical method group after a conversation with the patients and their family, because of non-reassuring fetal heart rate patterns at the beginning of study. An analysis of the mechanical method group (67 cases) and pharmacological method group (59 cases) was performed. For patients undergoing either treatment, study data were complete except one patient in the mechanical method groups did not have an umbilical-cord arterial blood pH assessment. A complementary analysis was done comparing the original assigned mechanical group (66 cases) versus pharmacological group (60 cases). The result was similar (Figure 1). In the mechanical method group, nine patients’ catheters were expelled spontaneously after they went into active labor within 12 h of placement, including one patients where the catheter was removed early due to membrane rupture 4 h after catheter placement. In the pharmacological group, Assessed for eligibility (n=132) Declined to join the study (n=6)
Randomized (n=126)
Mechanical method
Pharmacological method
Double balloon catheter
Dinoprostone vaginal insert
Allocated (n=66)
Allocated (n=60)
Catheter insertion failure˄n=1˅ Choice for Dinoprostone vaginal insert (n=1)
Reassigned
Table 1. Demographic and baseline characteristics.
Variable Maternal age, years Gestational age on admission, days Baseline Bishop Score
Mechanical method (n ¼ 67)
Pharmacological method (n ¼ 59)
p value
27.9 ± 3.9 275 ± 15
27.8 ± 3.4 273 ± 9
0.36 0.34
2.4 ± 0.8
2.5 ± 0.7
0.32
Non-reassuring fetal heart rate patterns (n=3)
Reassigned Analysed (n=67)
Analysed (n=59)
Figure 1. Flow of patients through the trial.
Safer method of labor induction
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DOI: 10.3109/14767058.2014.880880
the treatment was stopped prior to 24 h after insert placement, including seven patients for non-reassuring fetal heart patterns and another two patients for tachysystole. In one patient, the vaginal insert fell out after a vaginal exam. Tachysystole was not observed in the mechanical device group (Table 2). The cesarean section rate (CSR) was lower in the mechanical group (16%) than the pharmacological group (22%), but this difference was not statistically significant. The incidence of excessive uterine activity was significantly lower in the mechanical group than the pharmacological group (p50.05). The rate of non-reassuring fetal heart rate status was significantly lower in the mechanical group than the pharmacological group (p50.05). Consequently CSR for non-reassuring heart rate status was also less in the mechanical group. Improvement in the Bishop Score after ripening, time to vaginal delivery, and vaginal delivery within 24 h from initiation of either procedure was similar. Twentythree patients (34.3%) in the mechanical group and 30 patients (50.8%) in the pharmacological group went into active labor during the ripening process, without any statistical significance between them. There was more intervention of oxytocin infusion and amniotomy in the mechanical method group than in the pharmacological method group (p50.05). Birth canal injury, precipitous delivery, postpartum hemorrhage, and the volume of postpartum blood loss were not significantly different between the groups. No serious side-effects such as maternal placental abruption were found in either group. Neonatal outcomes (which included birth weight, 5-min Apgar scores57, umbilical-cord arterial blood pH, and rate of admission to the Neonatal Intensive Care Unit) were similar among the groups. Newborn infants with an umbilicalcord arterial blood pH57.1 were more frequently seen in the pharmacological method group than in the mechanical
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method group (p50.05). There was no perinatal death in either group.
Discussion The World Health Organization (WHO) and the Pan American Health Organization (PAHO) have recommended that the CSR in pregnancy should optimally be less than 15% [8]. But the global CSR has apparently been rising everywhere in recent years [2,9]. The high CSR in China has aroused the attention of the world. Our previous research reported [10] that the rate of postpartum hemorrhage and the volume of postpartum blood loss at cesarean delivery were significantly higher than vaginal delivery, even after induction of labor by double balloon catheter or dinoprostone 10 mg controlled-release vaginal insert. Postpartum hemorrhage is the direct cause of 30% maternal deaths worldwide [11]. In order to improve maternal and infant outcomes, it seems clear that cesarean section should be limited to pregnant women who have clear medical indications. This is particularly true in China. Oligohydramnios often occurs in post-term pregnancy, intrauterine growth restriction (IUGR), and premature rupture of membrane [3]. Oligohydramnios is associated with an increase in perinatal morbidity and mortality [12], such as non-reassuring fetal heart rate status during labor, meconium aspiration syndrome, and perinatal asphyxia [13,14]. In several countries, most pregnant women with oligohydramnios undergo cesarean section. The CSR of pregnant women with oligohydramnios has been reported to be five times higher than those with normal amniotic fluid volume [15]. The neonatal morbidity and mortality rates are also increased in oligohydramnios. Successful vaginal delivery after
Table 2. Induction, intrapartum, and neonatal outcomes. Mechanical method (n ¼ 67)
Pharmacological method (n ¼ 59)
p value
Improvement in Bishop Score Bishop Score56 after 12 h, n (%) Excessive uterine activity Nonreassuring fetal heart Onset of active labor, n (%) Oxytocin infusion, n (%) Amniotomy, n (%)
4 ± 1.4 13 (19.4) 3 (4.5%) 1 (1.5%) 23 (34.3) 43 (64.2) 49 (73.1)
3.4 ± 1.4 19 (32.2) 10 (16.9%) 9 (15.3%) 30 (50.8) 13 (22.0) 24 (40.7)
0.27 0.10 0.04* 0.01* 0.61 0.00* 0.00*
Time to vaginal delivery, min Vaginal delivery within 24 h, n (%) Cesarean section, n (%) Failure to progress, n (%) Fetal distress, n (%) Others, n (%) Birth canal injury, n (%) Precipitous delivery, n (%) Postpartum hemorrhage, n (%) Volume of postpartum blood loss, mL
1170 ± 323 40 (59.7) 11 (16.4) 7 (63.6) 1 (9.1) 3 (27.3) 1 (1.5) 1 (1.5) 1 (1.5) 202 ± 97
1122 ± 537 36 (61.0) 13 (22.0) 5 (38.5) 7 (53.8) 1 (7.7) 5 (8.5) 3 (5.1) 2 (3.4) 218 ± 102
0.54 0.88 0.42 0.71 0.03* 0.62 0.10 0.34 0.60 0.38
Newborn birthweight, g Newborn asphyxia, n (%) 5-min Apgar Score 57, n (%) Umbilical-cord arterial blood pH pH 57.1, n (%) NICU admission, n (%)
3157 ± 317 3 (4.5) 0 (0) 7.2 ± 0.6 4 (6) 0 (0)
3172 ± 402 3 (5.1) 2 (3.4) 7.1 ± 0.1 15 (25) 2 (3.4)
0.82 1.00 0.22 0.06 0.03* 0.22
OR (95% CI) 0.51 0.23 0.08 0.51 6.34 3.97
(0.22,1.15) (0.06,0.88) (0.01,0.69) (0.25,1.04) (2.87,14.01) (1.88,8.40)
0.95 0.70 1.26 1.11 2.72 0.16 0.28 0.43
(0.46,1.94) (0.29,1.70) (0.38,4.21) (0.01,0.94) (0.28,26.87) (0.02,1.44) (0.03,2.80) (0.04,4.89)
0.88 (0.17,4.51) 1.04 (0.99,1.09) 0.19 (0.06,0.60) 1.04 (0.99,1.09)
*The difference was statistically significant between the mechanical method group and the pharmacological method group.
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induction has been reported to occur in 40% of patients with oligohydramnios [12]. A range of methods, including mechanical and pharmacological methods, are available for cervical ripening including the use of dinoprostone vaginal inserts [16]. Dinoprostone is the most commonly available pharmacologic ripening agent used in China and many other countries. Mechanical methods including the double balloon catheter have been recommended for cervical ripening by ACOG in 2009 [3,4,17]. This method has more recently been introduced to China in 2010. Our previous research [5] showed that when used for labor induction, the double balloon catheter may be more effective than dinoprostone vaginal inserts. We reported a shorter second stage of labor and fetal intolerance of labor in patients after induction with a double balloon catheter. The mechanism of ripening/induction of double balloon catheter is thought to occur via local endogenous prostaglandin synthesis within the cervical stroma, resulting in cervical ripening. The results of this study show that both methods can promote cervical ripening effectively and should significantly reduce the CSR of pregnant women with oligohydramnios. After induction with double balloon catheter, the overall rates of excessive uterine activity, non-reassuring fetal heart, and the rate of cesarean delivery for non-reassuring fetal status were significantly lower. Induction with double balloon catheter was associated with non-significant reduction in the observed rate of precipitous delivery, newborn asphyxia, and postpartum hemorrhage. With increasing advances in perinatal medicine, ultrasound, and electronic fetal monitoring, it is often possible nowadays to choose the most reasonable delivery method in order to achieve the best perinatal result. Oligohydramnios is not an absolute indication for CS. Both dinoprostone vaginal insert and double balloon catheter can promote cervical ripening and improve the rate of vaginal delivery of the oligohydramnios. Compared with dinoprostone vaginal inserts, double balloon catheter seems safer to induce labor for pregnant women with oligohydramnios. We speculate that double balloon catheter will help to reduce the CSR and result in safer fetal outcomes.
Acknowledgements Authors are grateful to Dr. Reginald Tsang, MD, University of Cincinnati, Cincinnati Children’s Hospital, for help in editing this manuscript.
Declaration of interest This study complies with current ethical consideration. We also confirm that all the listed authors have participated actively in this study and have reviewed and approved this
J Matern Fetal Neonatal Med, 2014; 27(17): 1805–1808
manuscript. The authors do not have any possible conflicts of interest. The authors would like to acknowledge the financial support of The People’s Liberation Army Nanjing Military Area Command Medicine Health Department in China.
References 1. Bishop EH. Pelvic scoring for elective induction. Obstet Gynecol 1964;24:266–8. 2. Lumbiganon P, Laopaiboon M, Gulmezoglu AM, et al. Method of delivery and pregnancy outcomes in Asia: the WHO global survey on maternal and perinatal health 2007–08. Lancet 2010;375: 490–9. 3. Alchalabi HA, Obeidat BR, Jallad MF, et al. Induction of labor and perinatal outcome: the impact of the amniotic fluid index. Eur J Obstet Gynecol Report Biol 2006;129:124–7. 4. Pennell CE, Henderson JJ, O’Neill MJ, et al. Induction of labour in primiparous women with an unfavorable cervix: a randomised controlled trial comparing double and single balloon catheters and PGE2 gel. BJOG 2009;116:1443–52. 5. Jianlan Zheng, JingLi Fu, XiaoQiong Zhang, et al. A randomized controlled trial comparing double balloon catheter with dinoprostone 10 mg controlled-release vaginal insert to promote cervical mature and induction of labor. Chin J Obstet Gynecol 2011;46: 610–12 [Article in Chinese]. 6. Cromi A, Ghezzi F, Uccella S, et al. A randomised trial of preinduction cervical ripening: dinoprostone vaginal insert versus double-balloon catheter. Am J Obestet Gynecol 2012;207: e1–7. 7. Phelan JP, Smith CV, Broussard P, Small M. Amniotic fluid volume assessment with the four-quadrant technique at 36–42 weeks’ gestation. J Report Med 1987;32:540–2. 8. Moore B. Appropriate technology for birth. Lancet 1985;2:436–7. 9. Klemetti R, Che X, Gao Y, et al. Cesarean section delivery among primiparous women in rural China: an emerging epidemic. Am J Obstet Gynecol 2010;202:65.e1–6. 10. JingLi Fu, Jianlan Zheng, XiaoQiong Zhang, et al. The clinical analysis of postpartum hemorrhage. Progr. Obstet Gynecol 2012; 21:215–17 [Article in Chinese]. 11. World Health Organization. Maternal mortality in 2000: estimates developed by WHO, UNICEF, and UNFPA[R]. Geneva: World Health Organization; 2004. 12. Casey BM, Mcintire DD, Bloom SL, et al. Pregnancy outcomes after antepartum diagnosis of oligohydramnios at or beyond 34 weeks’ gestation. Am J Obstet Gynecol 2000;182: 909–12. 13. Hsieh TT, Hung TH, Chen KC, et al. Perinatal outcome of oligohydramnios without associated premature rupture of the membranes and fetal anomalies. Gynecol Obestet Invest 1998;45: 232–6. 14. Divon MY, Marks AD, Henderson CE, et al. Longitudinal measurement of amniotic fluid index in post-term pregnancies and its association with fetal outcome. Am J Obstet Gynecol 1995; 172:142–6. 15. Gary C, Paul M, Norman FG, et al. Williams Obstetrics [M]. 20th ed. Stanford: Appleton & Lange; 1997:664. 16. Hughes EG, Kelly AJ, Kavanagh J. Dinoprostone vaginal insert for cervical ripening and labor induction: a meta-analysis. Obstet Gynecol 2001;97:847–55. 17. ACOG Practice Bulletin No. 107: induction of labor. Obstet Gynecol 2009;114:386–97.
ORIGINAL ARTICLE
J Matern Fetal Neonatal Med Downloaded from informahealthcare.com by Selcuk Universitesi on 01/08/15 For personal use only.
Which is the safer method of labor induction for oligohydramnios women? Transcervical double balloon catheter or dinoprostone vaginal insert WenYan Wang1, Jianlan Zheng1,2, JingLi Fu1, XiaoQiong Zhang1, QinLing Ma1, ShuiLan Yu1, MeiYing Li3, and Li Hou3 1
Department of Obstetric, The People’s Liberation Army 174th Hospital, Xiamen, China, 2Medical College, Xiamen University, Xiang’an, Xiamen, China, and 3People’s Liberation Army 174th Clinical College, Anhui Medical University, Ximen, China
Abstract
Keywords
Objective: To compare the effectiveness and safety of two cervical ripening methods in term primiparous women with unfavorable cervices and oligohydramnios. Methods: Women (126 cases) with oligohydramnios [amniotic fluid index (AFI) 5 cm] and a low Bishop Score (6) were assigned randomly to use double balloon catheter (mechanical method group, 67 cases) or dinoprostone 10 mg controlled-release vaginal insert (pharmacological method group, 59 cases) for induction of labor. The study’s primary outcome was caesarean section rate (CSR). The secondary outcome measures included maternal and neonatal morbidity, an incremental changes in Bishop Score, and intrapartum interventions. Results: There was no significant difference between the mechanical method group and the pharmacological method group in CSR and change in Bishop Score. Tacysystole, non-reassuring fetal heart patterns, and cases of newborn umbilical-cord arterial blood pH57.1 were significantly lower with the mechanical method compared with the pharmacological method (p50.05). More patients needed additional intervention in the mechanical method group. Conclusions: Both methods resulted in a similar CSR. Double balloon catheter resulted in fewer labor complications, but more frequent use of oxytocin and amniotomy. Compared with dinoprostone vaginal insert, double balloon catheter use may be less problematic in women with oligohydramnios.
Cervical ripening, double balloon catheter, dinoprostone vaginal insert, induction of labor, oligohydramnios
Introduction Cervical assessment is recognized as having a significant impact on successful labor induction for more than 40 years [1]. Induction of labor is an increasingly common obstetric intervention. Successful induction in the patient with an unfavorable cervix is a frequent challenge that obstetricians face. In China, the issue of unsuccessful induction is a particular problem. China’s overall CSR is 46.2% and the CSR without medical indication occurs in 11.7% [2] of cases. There is a large body of research directed at comparing pharmacologic agents or mechanical devices in an effort to identify the best methods of cervical ripening. Prostaglandin cervical ripening in the form of a dinoprostone 10 mg controlled-release vaginal insert as the pharmacologic method has gained widespread use in clinical practice. This method has never been studied in patients with oligohydramnios, where there is an increase chance of non-reassuring fetal heart rate abnormalities during labor [3]. Furthermore, Address for correspondence: Jianlan Zheng, Department of Obstetric, The People’s Liberation Army 174th Hospital, OB, 96 Wenyuan Road, Xiamen 361003, China. E-mail: [email protected]
History Received 12 November 2013 Revised 30 December 2013 Accepted 5 January 2014 Published online 3 February 2014
oligohydramnios is often a medical indication for induction of labor. Mechanical balloon cervical ripening is another option that is used to initiate induction of labor in patient with an unfavorable cervix. Effectiveness of cervical balloon ripening has been debated [4–6]. In the present study, we analyzed the pregnancy outcomes and success of induction through the use of dinoprostone 10 mg controlled-release vaginal insert or double balloon catheter in women with oligohydramnios.
Materials and methods Between April 2010 and February 2011, 132 term primiparous women with oligohydramnios were assessed for eligibility in this study. The investigation was conducted in the Obstetrics Department of The People’s Liberation Army 174th Hospital, Xiamen, China. Oligohydramnios was defined as an amniotic fluid index (AFI) 5 cm [7]. AFI was reconfirmed by one of the investigators prior to randomization. Other inclusion criteria were gestational age beyond 37 0/7 weeks’, singleton pregnancy, vertex presentation, Bishop Score 6, intact membranes, the absence of documented uterine contractions, the absence of prior
J Matern Fetal Neonatal Med Downloaded from informahealthcare.com by Selcuk Universitesi on 01/08/15 For personal use only.
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J Matern Fetal Neonatal Med, 2014; 27(17): 1805–1808
C-section delivery history, and reassuring antenatal fetal testing (non-stress test, NST) active, and oxytocin challenge test (OCT) negative upon study entry. Women with antepartum bleeding, chorioamnionitis, placenta previa, or any other contraindication to vaginal delivery were excluded. Patients with a documented prostaglandin allergy, maternal asthma history, vaginitis or cervicitis at presentation, and/or glaucoma history were not eligible for the pharmacological treatment arm. This study protocol was approved and reviewed by the Institutional Ethics Committee of The People’s Liberation Army 174th Hospital, China. After written informed consent was obtained, and assessment of fetal condition and Bishop Score, women were randomly allocated to induction with either mechanical method or pharmacological method (sealed envelope randomization) (Table 1). In the mechanical method group, a double balloon catheter, the cervical ripening balloon (CRB) [Cook Medical Incorporated] was used. The CRB was inserted through the endocervical canal with both balloons ultimately filled with 80 mL of sterile 0.9% NaCl after seating the uterine balloon at the internal os and the vaginal balloon at the external os. The external end of the catheter was taped without traction to the patient’s thigh. Catheter placement was limited to a maximum of 12 h. Catheter removal occurred earlier upon rupture of amniotic membranes or when spontaneously expelled in active labor. In the pharmacological method group, the dinoprostone 10 mg controlled-release vaginal insert [Controlled Therapeutics (Scotland) Limited, East Kilbride, Scotland] was inserted into the subject’s posterior vaginal fornix. Prostaglandin insert removal occurred after 24 h of exposure. Prostaglandin was removed earlier in the presence of active labor or non-reassuring fetal heart rate monitoring. Both groups were monitored for uterine activity and fetal heart rate for at least 0.5 h after the catheter or pharmacologic agent was placed. Subjects were then allowed to ambulate, with periodic heart rate monitoring every 2–4 h. Oxytocin was used after 24 h of unsuccessful ripening, with a 30-min delay between device or medication removal and initiation of oxytocin. Oxytocin was also used for augmentation in active labor for the management of arrest disorders. Two patients needed replacement of their balloon catheter and one needed replacement of prostaglandin insert. All the outcome data were obtained concurrently and recorded by the research team. Statistical analysis of outcomes data was performed with the SPSS for Windows (SPSS version 13.0, SPSS Inc., Chicago, IL) statistical package. Continuous variables were expressed as mean ± SD and compared using t-test and discrete data
with chi-squared test or Fisher’s exact test. A p value of50.05 was established as the level of significance.
Results Six of the 132 primiparous women with oligohydramnios and unfavorable cervix declined to join the study, and declined either of the two methods. All these six patients chose cesarean delivery without induction of labor. One hundred twenty-six subjects were randomized between the two methods. Two patients who were allocated to the mechanical method group were reassigned to the pharmacological method group (one because of catheter insertion failure and one refused catheter placement). Three patients, who were allocated to the pharmacological method group, were reassigned to the mechanical method group after a conversation with the patients and their family, because of non-reassuring fetal heart rate patterns at the beginning of study. An analysis of the mechanical method group (67 cases) and pharmacological method group (59 cases) was performed. For patients undergoing either treatment, study data were complete except one patient in the mechanical method groups did not have an umbilical-cord arterial blood pH assessment. A complementary analysis was done comparing the original assigned mechanical group (66 cases) versus pharmacological group (60 cases). The result was similar (Figure 1). In the mechanical method group, nine patients’ catheters were expelled spontaneously after they went into active labor within 12 h of placement, including one patients where the catheter was removed early due to membrane rupture 4 h after catheter placement. In the pharmacological group, Assessed for eligibility (n=132) Declined to join the study (n=6)
Randomized (n=126)
Mechanical method
Pharmacological method
Double balloon catheter
Dinoprostone vaginal insert
Allocated (n=66)
Allocated (n=60)
Catheter insertion failure˄n=1˅ Choice for Dinoprostone vaginal insert (n=1)
Reassigned
Table 1. Demographic and baseline characteristics.
Variable Maternal age, years Gestational age on admission, days Baseline Bishop Score
Mechanical method (n ¼ 67)
Pharmacological method (n ¼ 59)
p value
27.9 ± 3.9 275 ± 15
27.8 ± 3.4 273 ± 9
0.36 0.34
2.4 ± 0.8
2.5 ± 0.7
0.32
Non-reassuring fetal heart rate patterns (n=3)
Reassigned Analysed (n=67)
Analysed (n=59)
Figure 1. Flow of patients through the trial.
Safer method of labor induction
J Matern Fetal Neonatal Med Downloaded from informahealthcare.com by Selcuk Universitesi on 01/08/15 For personal use only.
DOI: 10.3109/14767058.2014.880880
the treatment was stopped prior to 24 h after insert placement, including seven patients for non-reassuring fetal heart patterns and another two patients for tachysystole. In one patient, the vaginal insert fell out after a vaginal exam. Tachysystole was not observed in the mechanical device group (Table 2). The cesarean section rate (CSR) was lower in the mechanical group (16%) than the pharmacological group (22%), but this difference was not statistically significant. The incidence of excessive uterine activity was significantly lower in the mechanical group than the pharmacological group (p50.05). The rate of non-reassuring fetal heart rate status was significantly lower in the mechanical group than the pharmacological group (p50.05). Consequently CSR for non-reassuring heart rate status was also less in the mechanical group. Improvement in the Bishop Score after ripening, time to vaginal delivery, and vaginal delivery within 24 h from initiation of either procedure was similar. Twentythree patients (34.3%) in the mechanical group and 30 patients (50.8%) in the pharmacological group went into active labor during the ripening process, without any statistical significance between them. There was more intervention of oxytocin infusion and amniotomy in the mechanical method group than in the pharmacological method group (p50.05). Birth canal injury, precipitous delivery, postpartum hemorrhage, and the volume of postpartum blood loss were not significantly different between the groups. No serious side-effects such as maternal placental abruption were found in either group. Neonatal outcomes (which included birth weight, 5-min Apgar scores57, umbilical-cord arterial blood pH, and rate of admission to the Neonatal Intensive Care Unit) were similar among the groups. Newborn infants with an umbilicalcord arterial blood pH57.1 were more frequently seen in the pharmacological method group than in the mechanical
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method group (p50.05). There was no perinatal death in either group.
Discussion The World Health Organization (WHO) and the Pan American Health Organization (PAHO) have recommended that the CSR in pregnancy should optimally be less than 15% [8]. But the global CSR has apparently been rising everywhere in recent years [2,9]. The high CSR in China has aroused the attention of the world. Our previous research reported [10] that the rate of postpartum hemorrhage and the volume of postpartum blood loss at cesarean delivery were significantly higher than vaginal delivery, even after induction of labor by double balloon catheter or dinoprostone 10 mg controlled-release vaginal insert. Postpartum hemorrhage is the direct cause of 30% maternal deaths worldwide [11]. In order to improve maternal and infant outcomes, it seems clear that cesarean section should be limited to pregnant women who have clear medical indications. This is particularly true in China. Oligohydramnios often occurs in post-term pregnancy, intrauterine growth restriction (IUGR), and premature rupture of membrane [3]. Oligohydramnios is associated with an increase in perinatal morbidity and mortality [12], such as non-reassuring fetal heart rate status during labor, meconium aspiration syndrome, and perinatal asphyxia [13,14]. In several countries, most pregnant women with oligohydramnios undergo cesarean section. The CSR of pregnant women with oligohydramnios has been reported to be five times higher than those with normal amniotic fluid volume [15]. The neonatal morbidity and mortality rates are also increased in oligohydramnios. Successful vaginal delivery after
Table 2. Induction, intrapartum, and neonatal outcomes. Mechanical method (n ¼ 67)
Pharmacological method (n ¼ 59)
p value
Improvement in Bishop Score Bishop Score56 after 12 h, n (%) Excessive uterine activity Nonreassuring fetal heart Onset of active labor, n (%) Oxytocin infusion, n (%) Amniotomy, n (%)
4 ± 1.4 13 (19.4) 3 (4.5%) 1 (1.5%) 23 (34.3) 43 (64.2) 49 (73.1)
3.4 ± 1.4 19 (32.2) 10 (16.9%) 9 (15.3%) 30 (50.8) 13 (22.0) 24 (40.7)
0.27 0.10 0.04* 0.01* 0.61 0.00* 0.00*
Time to vaginal delivery, min Vaginal delivery within 24 h, n (%) Cesarean section, n (%) Failure to progress, n (%) Fetal distress, n (%) Others, n (%) Birth canal injury, n (%) Precipitous delivery, n (%) Postpartum hemorrhage, n (%) Volume of postpartum blood loss, mL
1170 ± 323 40 (59.7) 11 (16.4) 7 (63.6) 1 (9.1) 3 (27.3) 1 (1.5) 1 (1.5) 1 (1.5) 202 ± 97
1122 ± 537 36 (61.0) 13 (22.0) 5 (38.5) 7 (53.8) 1 (7.7) 5 (8.5) 3 (5.1) 2 (3.4) 218 ± 102
0.54 0.88 0.42 0.71 0.03* 0.62 0.10 0.34 0.60 0.38
Newborn birthweight, g Newborn asphyxia, n (%) 5-min Apgar Score 57, n (%) Umbilical-cord arterial blood pH pH 57.1, n (%) NICU admission, n (%)
3157 ± 317 3 (4.5) 0 (0) 7.2 ± 0.6 4 (6) 0 (0)
3172 ± 402 3 (5.1) 2 (3.4) 7.1 ± 0.1 15 (25) 2 (3.4)
0.82 1.00 0.22 0.06 0.03* 0.22
OR (95% CI) 0.51 0.23 0.08 0.51 6.34 3.97
(0.22,1.15) (0.06,0.88) (0.01,0.69) (0.25,1.04) (2.87,14.01) (1.88,8.40)
0.95 0.70 1.26 1.11 2.72 0.16 0.28 0.43
(0.46,1.94) (0.29,1.70) (0.38,4.21) (0.01,0.94) (0.28,26.87) (0.02,1.44) (0.03,2.80) (0.04,4.89)
0.88 (0.17,4.51) 1.04 (0.99,1.09) 0.19 (0.06,0.60) 1.04 (0.99,1.09)
*The difference was statistically significant between the mechanical method group and the pharmacological method group.
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induction has been reported to occur in 40% of patients with oligohydramnios [12]. A range of methods, including mechanical and pharmacological methods, are available for cervical ripening including the use of dinoprostone vaginal inserts [16]. Dinoprostone is the most commonly available pharmacologic ripening agent used in China and many other countries. Mechanical methods including the double balloon catheter have been recommended for cervical ripening by ACOG in 2009 [3,4,17]. This method has more recently been introduced to China in 2010. Our previous research [5] showed that when used for labor induction, the double balloon catheter may be more effective than dinoprostone vaginal inserts. We reported a shorter second stage of labor and fetal intolerance of labor in patients after induction with a double balloon catheter. The mechanism of ripening/induction of double balloon catheter is thought to occur via local endogenous prostaglandin synthesis within the cervical stroma, resulting in cervical ripening. The results of this study show that both methods can promote cervical ripening effectively and should significantly reduce the CSR of pregnant women with oligohydramnios. After induction with double balloon catheter, the overall rates of excessive uterine activity, non-reassuring fetal heart, and the rate of cesarean delivery for non-reassuring fetal status were significantly lower. Induction with double balloon catheter was associated with non-significant reduction in the observed rate of precipitous delivery, newborn asphyxia, and postpartum hemorrhage. With increasing advances in perinatal medicine, ultrasound, and electronic fetal monitoring, it is often possible nowadays to choose the most reasonable delivery method in order to achieve the best perinatal result. Oligohydramnios is not an absolute indication for CS. Both dinoprostone vaginal insert and double balloon catheter can promote cervical ripening and improve the rate of vaginal delivery of the oligohydramnios. Compared with dinoprostone vaginal inserts, double balloon catheter seems safer to induce labor for pregnant women with oligohydramnios. We speculate that double balloon catheter will help to reduce the CSR and result in safer fetal outcomes.
Acknowledgements Authors are grateful to Dr. Reginald Tsang, MD, University of Cincinnati, Cincinnati Children’s Hospital, for help in editing this manuscript.
Declaration of interest This study complies with current ethical consideration. We also confirm that all the listed authors have participated actively in this study and have reviewed and approved this
J Matern Fetal Neonatal Med, 2014; 27(17): 1805–1808
manuscript. The authors do not have any possible conflicts of interest. The authors would like to acknowledge the financial support of The People’s Liberation Army Nanjing Military Area Command Medicine Health Department in China.
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