Ping Wang
Yan Hu- Department of Obstetrics and Gynecology, Linping Campus, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
Objective: To conduct a meta-analysis comparing Bishop scores in newborns resulting from single balloon versus double balloon labor induction methods.
Methods: We performed a meta-analysis of RCT's that compared single and double balloon catheters for inducing labor. Relevant literature studies were located by searching PubMed, MEDLINE, EMBASE, and the Cochrane Library. The primary outcome measure was the Bishop score, while secondary outcomes included the mode of delivery, complications, time interval from catheter insertion to the delivery, and the Apgar score at five minutes.
Results: Our meta-analysis encompassed 6 RCT involving 996 women who underwent labor induction. We detected a substantial variation in the Bishop scores, with SBC induction yielding higher scores. Specifically, neonates delivered using SBC had higher Bishop scores than those delivered using DBC. This highlights the clinical significance of Bishop scores in identifying infants who may require immediate medical attention. However, no significant differences were found in mode of delivery, complications, or Apgar scores between the two groups (P > 0.05).
Conclusion: Labor induction using a single balloon catheter appears to be more effective at ripening the cervix, as indicated by higher Bishop scores. This suggests that it might be a more favorable method for inducing labor.
1 Introduction
There is growing global concern over the rising incidence of labor inductions prior to 41 weeks, in the absence of maternal or fetal complications, due to the potential risk of iatrogenic harm to both the mother and baby (1, 2). Over the past decade, the rate of labor induction has seen a substantial rise, with elective labor inductions playing a significant role in this increasing trend (3). The CS rate continues to increase across all levels of hospitals in China (4). As the cesarean section rate rises, pregnancies involving a scarred uterus have become more frequent. A previous uterine scar heightens the risk of uterine rupture and other complications during vaginal delivery (5).
Successful labor induction is contingent upon cervical favorability. Cervical ripening modalities encompass pharmacologic agents and mechanical devices (6). The World Health Organization (WHO) has deemed mechanical ripening with balloon catheters and pharmacologic ripening with prostaglandins, including misoprostol, to be both acceptable and safe (7). Although balloon catheters and vaginal prostaglandins demonstrate similar cesarean delivery rates and maternal safety profiles in labor induction, balloon catheters are associated with a lower incidence of adverse perinatal events (8). Nonetheless, a novel meta-analysis is warranted to juxtapose the effectiveness and protection of SBC vs. DBC, given the paucity of comparative evidence currently available.
The SBC (Foley) is widely utilized mechanical technique for cervical ripening, with origins in 1960s (9). The Atad catheter, introduced in the 1990s (10), was the initial DBC variant of this device. The Cook Cervical Ripening Balloon, which received approval from the United States Food and Drug Administration in 2013, operates on the same principle as the Atad catheter. Both Foley and Atad or Cook catheters are operative mechanical means of ripening the cervix. It is claimed that, in contrast to the Foley catheter, the Atad or Cook catheter applies the dilator vector bilaterally to the cervix, thus eliminating the need for traction.
Cost-effectiveness of medical devices is a global concern, especially in settings with limited resources. In 2025, as medical technology continues to advance, there is increasing focus on the cost-effectiveness of these devices (11). We conducted a systematic review and meta-analysis to compare the efficacy and safety of two mechanical induction methods for an unfavorable cervix: SBC vs. DBC.
2 Materials and methods
2.1 Data collection
We performed comprehensive research of PubMed, MEDLINE, EMBASE, and the Cochrane Library, strictly following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (26). Our study examines the outcomes of SBC vs. DBC labor induction, with a particular emphasis on Bishop scores, as depicted in PRISMA chart (Figure 1). This method ensures transparency and thoroughness in reporting this study.
Figure 1. Prisma flow chart.
Two reviewers independently conducted the literature search and extracted data on study design, patient recruitment, inclusion and exclusion criteria, test details, results, and quality assessment. In this analysis concentrated on outcomes associated with effectiveness and adverse events, including mode of delivery (spontaneous vaginal delivery, CS rate, and instrumental delivery), vaginal delivery in 24 h, time from catheter insertion to delivery, improvement in Bishop Score, complications during pregnancy (such as cord prolapse, placental abruption, febrile morbidity, postpartum hemorrhage, malpresentation, and maternal satisfaction), and the proportion of neonates with 5-min Apgar scores below 7. To evaluate the quality of the included RCTs, we utilized the RevMan bias chart, as illustrated in Figure 2.
Figure 2. Studies bias chart.
2.2 PICO
Population: Articles were searched in PubMed, MEDLINE, EMBASE, and the Cochrane Library databases up to the current date (January 2025).
Intervention: SBC induction of labor.
Comparison: SBC vs. DBC induction of labor.
Outcome: Significant differences in Bishop score, indicating better immediate neonatal outcomes with SBC induction.
2.3 Inclusion criteria
Our review encompassed RCT's that compared SBC induction of labor with DBC induction in pregnant women, published up to January 2025 and accessible in full text from PubMed, MEDLINE, EMBASE, and the Cochrane Library. To be eligible, studies had to discuss the bishop score and provide data on the mode of delivery, complications, and Apgar score.
2.4 Exclusion criteria
To ensure the methodological soundness and relevance of the studies included in our research, we excluded non-RCT's, studies lacking applicable outcome data, those involving non-pregnant populations, studies with duplicate or overlapping data, non-comparative studies, non-human studies, and unpublished data.
2.5 Statistical analysis
We conducted an analysis with a 95% Confidence Interval (CI) by using RevMan 5.4 for summary statistics, which were organized based on descriptive analysis. Dichotomous data were presented as Odds Ratios (OR) with 95% CI, calculated via the Mantel-Haenszel method. Heterogeneity was evaluated using Q statistics, with total variation across studies assessed by I2, and significance set at P < 0.05. Heterogeneity was deemed substantial if I2 surpassed 75% and significant if P was less than 0.1, as determined by the Q test. In cases of no or minimal heterogeneity, we applied the fixed-effect model; otherwise, the random-effect model was used (12).
3 Results
3.1 Patient characteristics
Our search using the terms “single balloon,” “double balloon,” and “induction of labor” identified 178 articles from PubMed, MEDLINE, EMBASE, and the Cochrane Library. After screening the titles and abstracts, we omitted 132 articles due to duplication. We then retrieved 6 full-text articles for in-depth analysis. Of these, 119 were deemed irrelevant to our research as they did not compare single vs. double balloon induction of labor and included case reports, conference studies, literature reviews, or editorials. This process is illustrated in the PRISMA chart. The detailed characteristics of the studies are presented in Table 1.
Table 1. Study characteristics.
3.2 Mode of delivery
3.2.1 Spontaneous vaginal delivery
Incorporating data from six studies into our analysis, we found that the Single Balloon (SB) group included 527 cases, while the Double Balloon (DB) group included 450 cases. The analysis revealed no significant difference in the spontaneous vaginal delivery rate between the SB and DB groups (RR = 0.98, 95% CI: 0.90, 1.08, P = 0.73), as depicted in Figures 3A,B.
Figure 3. (A) Forest plot comparing SB and DB for spontaneous vaginal delivery (RR = 0.98, 95% CI: 0.90, 1.08, P = 0.73)). (B) A funnel plot for Spontaneous vaginal delivery.
3.2.2 Instrumental vaginal delivery
In this analysis data from four articles were included. The SB group comprised 434 cases, while the DB group comprised 368 cases. The analysis did not reveal a significant difference in the instrumental vaginal delivery rate. However, the results trended slightly in favor of the SB group compared to the DB group (RR = 0.87, 95% CI: 0.67, 1.14, P = 0.33), as depicted in Figures 4A,B.
Figure 4. (A) Forest plot comparing SB and DB for instrumental vaginal delivery. (RR = 0.87, 95% CI: 0.67, 1.14, P = 0.33). (B) Funnel plot for Instrumental vaginal delivery.
3.2.3 Cesarean section delivery
Incorporating data from five articles, our study included 482 cases in the SB group and 418 cases in the DB group. The analysis revealed no significant difference in the cesarean section delivery rate. However, the results trended slightly in favor of the DB group compared to the SB group (RR = 1.05, 95% CI: 0.84, 1.31, P = 0.67), as shown in Figures 5A,B.
Figure 5. (A) forest plot comparing SB and DB for caesarean section delivery. (RR = 1.05, 95% CI: 0.84, 1.31, P = 0.67). (B) Funnel plot for Caesarean section delivery.
3.3 Vaginal delivery <24 h
In this study, data from four articles were included. The SB group comprised 356 cases, while the DB group comprised 358 cases. The analysis revealed no significant difference in the rate of vaginal delivery within 24 h (RR = 1.03, 95% CI: 0.90, 1.17, P = 0.67), as depicted in Figures 6A,B.
Figure 6. (A) Forest plot comparing SB and DB for vaginal delivery <24 h. (RR = 1.03, 95% CI: 0.90, 1.17, P = 0.67). (B) Funnel plot for Vaginal delivery <24 h.
3.4 APGAR score at 5 min
Incorporating data from five articles, our study included 482 cases in the SB group and 418 cases in the DB group. The analysis revealed no significant difference in the Apgar score. However, the results trended slightly in favor of the SB group compared to the DB group (RR = 0.75, 95% CI: 0.39, 1.46, P = 0.40), as shown in Figures 7A,B.
![Combined image featuring a forest plot and a funnel plot. Panel A shows a forest plot comparing single and double balloon interventions with risk ratios for each study. Confidence intervals are depicted with horizontal lines, and an overall effect is shown as a diamond. Panel B presents a funnel plot showing SE(log[RR]) versus risk ratio, with dashed lines indicating expected distribution.\n\n](https://www.frontiersin.org/files/Articles/1584611/fsurg-12-1584611-HTML-r1/image_m/fsurg-12-1584611-g007.jpg)
Figure 7. (A) forest plot comparing SB and DB for APGAR score at 5 min. (RR = 0.75, 95% CI: 0.39, 1.46, P = 0.40). (B) Funnel plot for APGAR score at 5 min.
3.5 Bishop score
Our study incorporated data from five articles. The SB group included 419 cases, while the DB group included 341 cases. The analysis revealed a significant difference in the Bishop score, favoring the SB group over the DB group (RR = −0.32, 95% CI: −0.57, −0.07, P = 0.01), as depicted in Figures 8A,B.
Figure 8. (A) Forest plot comparing SB and DB for bishop score. (RR = −0.32, 95% CI: −0.57, −0.07, P = 0.01). (B) Funnel plot for Bishop score.
3.6 Catheter to delivery interval
Our study included data from a total of five articles. The SB group consisted of 461 cases, while the DB group consisted of 404 cases. The analysis did not show a significant difference in the catheter-to-delivery interval. However, the results trended in favor of the SB group compared to the DB group (RR = −0.71, 95% CI: −1.95, 0.53, P = 0.26), as illustrated in Figures 9A,B.
Figure 9. (A) Forest plot comparing SB and DB for catheter to delivery interval. (RR = −0.71, 95% CI: −1.95, 0.53, P = 0.26). (B) Funnel plot for Catheter to delivery interval.
3.7 Complications
Our study incorporated data from three articles in total. The SB group included 246 cases, while the DB group included 251 cases. The analysis did not show a significant difference in complications. However, the results trended slightly in favor of the SB group compared to the DB group (RR = 0.95, 95% CI: 0.85, 1.07, P = 0.39), as illustrated in Figures 10A,B.
Figure 10. (A) forest plot comparing SB and DB for complications. (RR = 0.95, 95% CI: 0.85, 1.07, P = 0.39). (B) Funnel plot for complications.
4 Discussion
We observed in our meta-analysis a noteworthy change in the Bishop score, favoring SBC induction of labor compared to DBC induction. Specifically, the Bishop score was significantly higher in the SBC group, indicating better cervical conditions for labor induction. This finding underscores the clinical significance of the Bishop score in predicting successful labor induction and vaginal delivery. The Bishop score evaluates several clinical parameters of the cervix, including dilation, effacement, position, consistency, and the fetal head's station in the pelvis. A more favorable cervical condition for labor induction is indicated by a higher Bishop score, which can lead to a higher likelihood of successful vaginal delivery (19).
Our findings are consistent with prior studies showing that a higher Bishop score correlates with a greater likelihood of successful labor induction. For instance, a study by Erasto et al. found that oxytocin was the most effective agent for labor induction, achieving a high rate of spontaneous vaginal delivery (SVD) within a shorter timeframe (20). Similarly, a systematic review and meta-analysis by Lajusticia et al. showed that SBC induction was associated with higher Bishop scores, indicating better cervical conditions for labor induction (21). These studies emphasize the significance of the Bishop score in evaluating the effectiveness of labor induction methods (22, 23).
Our analysis did not find significant differences in Apgar scores at 1 and 5 min, mode of delivery, or complications between the two groups. This suggests that while SBC induction may lead to better cervical conditions for labor, it does not necessarily translate to improved neonatal outcomes or differences in delivery methods and complications.
In our meta-analysis, the SBC was found to be more effective in promoting cervical ripening compared to the DBC. This could be attributed to several potential mechanisms. Firstly, the SBC may exert more consistent and localized pressure on the cervix, leading to more efficient mechanical dilation. Additionally, the single-balloon design might allow for better adaptation to the individual anatomy of the cervix, thereby enhancing its effectiveness (17). Furthermore, the presence of a SB could potentially reduce the risk of infection or other complications associated with the insertion and maintenance of the device (24). Future studies should investigate these mechanisms in more detail to elucidate the specific factors contributing to the observed differences.
The meta-analysis findings suggest that SBC are more effective for cervical ripening, potentially leading to shorter labor durations and reduced need for additional interventions like oxytocin (25). These results can guide clinicians in selecting the most suitable induction method, emphasizing the importance of considering patient-specific factors such as cervical maturity and contraindications.
There are several limitations to our meta-analysis that should be taken into account when interpreting the results. For instance, the methodological quality of the included studies varied, with some studies lacking rigorous randomization or blinding procedures. Additionally, incomplete data reporting in some studies limited our ability to perform more detailed subgroup analyses.
In conclusion, our meta-analysis underscores the significance of the Bishop score in evaluating the effectiveness of labor induction methods. SBC induction appears to be more effective in ripening the cervix, as indicated by higher Bishop scores. However, future research should aim to address these limitations by conducting high-quality randomized controlled trials with standardized protocols and comprehensive data reporting. Future research should address our meta-analysis limitations through high-quality RCTs with standardized protocols, diverse patient populations, and long-term follow-up. This will enhance understanding of induction methods' mechanisms, safety, and patient satisfaction.
5 Conclusion
Labor induction using a SBC appears to be more effective at ripening the cervix, as indicated by higher Bishop scores. This suggests that it might be a more favorable method for inducing labor.
Data availability statement
The original contributions presented in the study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding author.
Author contributions
PW: Conceptualization, Data curation, Methodology, Project administration, Visualization, Writing – original draft, Writing – review & editing. YH: Writing – review & editing. TS: Writing – review & editing. FF: Writing – review & editing.
Funding
The author(s) declare that no financial support was received for the research and/or publication of this article.
Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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Abbreviations
SBC, single balloon catheter; DBC, double balloon catheter; CS, cesarean section; RCT, randomized controlled trials; SB, single balloon; DB, double balloon.
References
1. Butler SE, Wallace EM, Bisits A, Selvaratnam RJ, Davey MA. Induction of labor and cesarean birth in lower-risk nulliparous women at term: a retrospective cohort study. Birth. (2024) 51:521–9. doi: 10.1111/birt.12806
2. McCarthy CM, Meaney S, McCarthy M, Conners N, Russell N. Induction of labor: reviewing the past to improve the future. AJOG Glob Rep. (2022) 2:100099. doi: 10.1016/j.xagr.2022.100099
3. Induction of labor. ACOG practice bulletin No. 107. American college of obstetricians and gynecologists. Obstet Gyne Col. (2009) 114:386–97. doi: 10.1097/AOG.0b013e3181b48ef5
4. Hou L, Hellerstein S, Vitonis A, Zou L, Ruan Y, Wang X, et al. Cross sectional study of mode of delivery and maternal and perinatal outcomes in mainland China. PLoS One. (2017) 12(2):e0171779. doi: 10.1371/journal.pone.0171779
5. Andrikopoulou M, Lavery JA, Ananth CV, Vintzileos AM. Cervical ripening agents in the second trimester of pregnancy in women with a scarred uterus: a systematic review and metaanalysis of observational studies. Am J Obstet Gynecol. (2016) 215:177–94. doi: 10.1016/j.ajog.2016.03.037
6. Durie D, Lawal A, Zegelbone P. Other mechanical methods for pre-induction cervical ripening. Semin Perinatol. (2015) 39:444–9. doi: 10.1053/j.semperi.2015.07.006
7. World Health Organization, Department of Reproductive Health and Research. WHO Recommendations for Induction of Labour. Geneva: World Health Organization (2011). Available online at: http://apps.who.int/iris/bitstream/10665/44531/1/9789241501156_eng.pdf
8. Jones MN, Palmer KR, Pathirana MM, Cecatti JG, Filho OBM, Marions L, et al. Balloon catheters versus vaginal prostaglandins for labour induction (CPI Collaborative): an individual participant data meta-analysis of randomised controlled trials. Lancet. (2022) 400(10364):1681–92. doi: 10.1016/S0140-6736(22)01845-1
9. Guinn DA, Davies JK, Jones RO, Sullivan L, Wolf D. Labor induction in women with an unfavorable Bishop score: randomized controlled trial of intrauterine Foley catheter with concurrent oxytocin infusion versus Foley catheter with extra-amniotic saline infusion with concurrent oxytocin infusion. Am J Obstet Gynecol. (2004) 191(1):225–9. doi: 10.1016/j.ajog.2003.12.039
10. Atad J, Bornstein J, Calderon J, Petrikovsky BM, Sorokin Y, Abramovici H. Nonpharmaceutical ripening of the unfavor able cervix and induction of labor by a novel double balloon device. Obstet Gynecol. (1991) 77:146–52. doi: 10.1016/0029-7844(95)00389-4
11. Saad AF, Pedroza C, Gavara R, Gupta J, Wapner RJ, Saade GR. Dilapan-S vs standard methods for cervical ripening in term pregnancies: an individual patient data meta-analysis. Am J Obstet Gynecol MFM. (2024) 7(1):101583. doi: 10.1016/j.ajogmf.2024.101583
12. Staniczek J, Manasar-Dyrbuś M, Rybak-Krzyszkowska M, Kondracka A, Winkowska E, Sadłocha M, et al. Labor induction in adolescent pregnancies—a scoping review. J Matern Fetal Neonatal Med. (2025) 38(1):2505083. doi: 10.1080/14767058.2025.2505083
13. Lee DS, Tandel MD, Kwan L, Francoeur AA, Duong HL, Negi M. Favorable simplified Bishop score after cervical ripening associated with decreased cesarean birth rate. American Journal of Obstetrics & Gynecology MFM. (2022) 4(2):100534. doi: 10.1016/j.ajogmf.2021.100534
14. Salim R, Zafran N, Nachum Z, Garmi G, Kraiem N, Shalev E. Single-balloon compared with double-balloon catheters for induction of labor: a randomized controlled trial. Obstet Gynecol. (2011) 118(1):79–86. doi: 10.1097/AOG.0b013e318220e4b7
15. Mei-Dan E, Walfisch A, Valencia C, Hallak M. Making cervical ripening EASI: a prospective controlled comparison of single versus double balloon catheters. J Matern Fetal Neonatal Med. (2014) 27(17):1765–70. doi: 10.3109/14767058.2013.879704
16. Hoppe KK, Schiff MA, Peterson SE, Gravett MG. 30 mL Single- versus 80 mL double-balloon catheter for pre-induction cervical ripening: a randomized controlled trial. J Matern Fetal Neonatal Med. (2016) 29(12):1919–25. doi: 10.3109/14767058.2015.1067297
17. Pez V, Deruelle P, Kyheng M, Boyon C, Clouqueur E, Garabedian C. Méthodes de maturation cervicale et déclenchement du travail: évaluation de la sonde simple ballonnet comparée à la sonde double ballonnet et aux prostaglandines [Cervical ripening and labor induction: evaluation of single balloon catheter compared to double balloon catheter and dinoprostone insert]. Gynecol Obstet Fertil Senol. (2018) 46(7–8):570–4. doi: 10.1016/j.gofs.2018.05.009
18. Xing Y, Li N, Ji Q, Hong L, Wang X, Xing B. Double-balloon catheter compared with single-balloon catheter for induction of labor with a scarred uterus. Eur J Obstet Gynecol Reprod Biol. (2019) 243:139–43. doi: 10.1016/j.ejogrb.2019.10.041
19. National Institute for Health and Care Excellence (NICE). Methods for the Induction of Labour: Inducing Labour: Evidence Review B. London: National Institute for Health and Care Excellence (NICE) (2021).
20. Wormer KC, Bauer A, Williford AE. Bishop score. In: StatPearls. Treasure Island (FL): StatPearls Publishing (2025). PMID: 29261961.
21. Li SF, Ju HH, Feng CS. Effect of cervical Bishop score on induction of labor at term in primiparas using Foley catheter balloon: a retrospective study. BMC Pregnancy Childbirth. (2024) 24(1):401. doi: 10.1186/s12884-024-06600-1
22. Sanchez-Ramos L, Levine LD, Sciscione AC, Mozurkewich EL, Ramsey PS, Adair CD, et al. Methods for the induction of labor: efficacy and safety. Am J Obstet Gynecol. (2024) 230(3S):S669–95. doi: 10.1016/j.ajog.2023.02.009
23. Lajusticia H, Martínez-Domínguez SJ, Pérez-Roncero GR, Chedraui P, Pérez-López FR, Health Outcomes and Systematic Analyses (HOUSSAY) Project. Single versus double-balloon catheters for the induction of labor of singleton pregnancies: a meta-analysis of randomized and quasi-randomized controlled trials. Arch Gynecol Obstet. (2018) 297(5):1089–100. doi: 10.1007/s00404-018-4713-9
24. Yi J, Chen L, Meng X, Chen Y. The infection, cervical and perineal lacerations in relation to postpartum hemorrhage following vaginal delivery induced by cook balloon catheter. Arch Gynecol Obstet. (2024) 309(1):159–66. doi: 10.1007/s00404-022-06861-1
25. Edwards RK, Szychowski JM, Berger JL, Petersen M, Ingersoll M, Bodea-Braescu AV, et al. Foley catheter compared with the controlled-release dinoprostone insert: a randomized controlled trial. Obstet Gynecol. (2014) 123(6):1280–7. doi: 10.1097/AOG.0000000000000238
Keywords: Bishop score, single balloon catheter, double balloon catheter, labor induction, neonatal outcomes
Citation: Wang P, Hu Y, Shan T and Fang F (2025) Significance of Bishop score in single vs. double balloon catheterization for induction in labor; a meta-analysis. Front. Surg. 12:1584611. doi: 10.3389/fsurg.2025.1584611
Received: 27 February 2025; Revised: 6 October 2025;
Accepted: 26 November 2025;
Published: 11 December 2025.
Edited by:
Sawsan Abuhammad, Jordan University of Science and Technology, JordanReviewed by:
Wensheng Zhu, Hubei University of Chinese Medicine, ChinaWensheng Zhu, Huanggang Hospital of Traditional Chinese Medicine, China
Copyright: © 2025 Wang, Hu, Shan and Fang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Ping Wang, d2FuZ3AyMDIzMTYzQDE2My5jb20=