Efficacy of OB Balloon Tamponade in Cesarean Delivery for Placenta Previa and Low-Lying Placenta: A Retrospective Comparative Study

Efficacy of OB Balloon Tamponade in Cesarean Delivery for Placenta Previa and Low-Lying Placenta: A Retrospective Comparative Study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Efficacy of OB Balloon Tamponade in Cesarean Delivery for Placenta Previa and Low-Lying Placenta: A Retrospective Comparative Study Iwao Yasoshima, Nao Hoshiba, Takashi Iizuka, Kyosuke Kagami, Masaaki Tanaka, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7147446/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 04 Feb, 2026 Read the published version in BMC Pregnancy and Childbirth → Version 1 posted 8 You are reading this latest preprint version Abstract Background Placenta previa and low-lying placenta are associated with substantial peripartum hemorrhagic complications, particularly during cesarean delivery. This retrospective study compared the efficacy and safety of a newly developed OB balloon—featuring a double-balloon structure designed to simultaneously compress the uterine and vaginal sides—with the conventional Bakri balloon for intrauterine tamponade. Methods We retrospectively analyzed cases of placenta previa or low-lying placenta managed with either the OB or Bakri balloon during cesarean delivery. The primary outcome was balloon failure, defined as inadequate postoperative bleeding control requiring additional interventions despite balloon tamponade. Secondary outcomes included insertion time, inflation volume, postoperative blood loss, and balloon prolapse. Results A total of 47 cases were analyzed: 20 in the OB group and 27 in the Bakri group. Balloon failure occurred in 5 cases (18.5%) in the Bakri group—all associated with balloon prolapse—whereas no failures occurred in the OB group. Balloon prolapse was observed in 6 cases (22.2%) in the Bakri group and none in the OB group. No significant differences were found in insertion time or postoperative blood loss between the groups. Conclusion The OB balloon reduced the incidence of balloon prolapse while maintaining comparable hemostatic efficacy. These findings suggest that the OB balloon offers a more stable hemostatic option for cesarean deliveries complicated by abnormal placentation. OB balloon cesarean section placenta previa double balloon tamponade Figures Figure 1 Introduction Placenta previa and low-lying placenta are abnormal placental implantations associated with substantial maternal and perinatal complications, particularly postpartum hemorrhage, which remains a leading cause of maternal mortality worldwide [ 1 ]. During cesarean delivery in such cases, effective hemorrhage control is crucial. Available techniques include intrauterine balloon tamponade, uterine compression sutures, arterial ligation, and resuscitative endovascular balloon occlusion of the aorta, with hysterectomy reserved as a last resort for uncontrolled bleeding [ 2 ]. Intrauterine balloon tamponade is a simple and effective method for managing postpartum hemorrhage; however, the balloon may prolapse into the vagina, resulting in inadequate hemostasis [ 3 , 4 ]. Dr. Tanaka, a co-author of this study, developed the OB balloon—a novel double-balloon catheter for uterine tamponade that was commercialized in Japan in 2022 (Fig. 1 A). The intrauterine balloon is positioned in the lower uterine segment, while the vaginal balloon is placed within the vaginal cavity to compress the cervix from both sides, thereby preventing prolapse of the intrauterine balloon into the vagina (Fig. 1 B). The term “OB” is derived from “obstetrics” and “obstruction” and serves as the product name “OB balloon,” emphasizing the device’s function in controlling obstetric hemorrhage. A distinctive feature of the OB balloon is that the primary connectors are located on the uterine side, allowing intraoperative adjustment of the inflation volumes of both balloons within the surgical field (Fig. 1 C). Postoperatively, the intrauterine balloon inflation can also be modified via an additional vaginal-side connector. The device is commercially available in Japan and has been adopted by multiple institutions. According to the manufacturer’s instructions, the intrauterine and vaginal balloons can be filled with up to 500 mL and 100 mL of fluid, respectively, although the attending obstetrician adjusts these volumes to achieve adequate compression in each case. The OB balloon placement procedure is illustrated in Fig. 1 D–F. The objective of this study was to compare the efficacy and performance of the OB balloon with the conventional Bakri® Postpartum Balloon during cesarean deliveries for placenta previa and low-lying placenta. Materials and Methods Study design and population This single-institution, retrospective study included all cesarean deliveries for placenta previa or low-lying placenta performed between January 2019 and December 2024. The study period was defined to encompass cases occurring both before and after the introduction of the OB balloon. We included cases in which intrauterine balloon tamponade was performed intraoperatively using either the OB balloon (OB group) or the Bakri balloon (Bakri group). At our institution, Bakri balloons were primarily used until October 2022, and OB balloons were predominantly employed from November 2022 onward, resulting in two historical control groups without temporal overlap in balloon use. The OB balloon was approved for clinical use in Japan in November 2022 and has since been incorporated into routine obstetric practice at our institution as one of the standard options for intrauterine balloon tamponade. Cases were excluded if no intrauterine balloon was used, insertion failed because of placement difficulty, a balloon other than the OB or Bakri type was used, or a planned peripartum hysterectomy was performed for placenta accreta spectrum (PAS). Data collection Clinical data were retrospectively extracted from electronic medical records at Kanazawa University Hospital. For all cesarean deliveries performed for placenta previa or low-lying placenta during the study period, we collected information on maternal demographics, obstetric history, gestational age at delivery, placenta type and position, timing of cesarean section (elective or emergency), operative time, and intraoperative blood loss. Complete placenta previa was defined as placental tissue covering the internal cervical os, whereas partial or marginal placenta previa was defined as the placental edge reaching but not covering the internal cervical os. Low-lying placenta was defined as the placental edge located within 20 mm of the internal cervical os. Placental position was categorized as anterior, posterior, or other. The latter category included fundal, lateral, or circumferential placentas in which the anterior or posterior location could not be clearly determined. For cases in which intrauterine balloon tamponade was used, additional procedure-related variables were collected, including balloon type (OB or Bakri), insertion time, indwelling duration, and postoperative blood loss measured within 2 hours after surgery as well as from the end of surgery until balloon removal. The presence of placenta accreta spectrum was also assessed. Postoperative outcomes were systematically recorded, including balloon prolapse, balloon reinsertion, transfusion, uterine artery embolization (UAE), additional surgical procedures, and postoperative complications such as infection or insertion-related injury. The timing of balloon prolapse events was documented as well. Balloon insertion procedures The balloon was placed intraoperatively at the discretion of the attending obstetrician when active bleeding, including persistent oozing, was observed after delivery of the fetus and placenta. In both groups, the attending obstetrician determined the indication for balloon placement and its final position, and the insertion procedure was standardized according to the institutional protocol. In the OB group, the balloon was inserted intraoperatively from the operative field by either the operating surgeon or the first assistant. After insertion, the vaginal balloon was inflated, and gentle traction was applied to confirm adequate expansion and fixation at the level of the vaginal canal. Subsequently, the uterine balloon was inflated under direct visualization within the surgical field. In the Bakri group, the balloon was inserted and positioned by either the operating surgeon or the first assistant, and inflation was performed by the second assistant from the vaginal side, outside the surgical field. Thus, the main difference between the two devices was not a fundamental difference in insertion technique but rather who performed the balloon inflation and where it occurred—in the operative field or from the vaginal side. At our institution, uterine muscle repair is typically performed using continuous two-layer barbed suturing. However, when an intrauterine balloon is placed, the uterine incision is closed with non-barbed, single-layer interrupted sutures in accordance with our institutional protocol. This modification is implemented to minimize the risk of inadvertent needle injury to the balloon. Postoperatively, a vaginal examination was performed to assess for active bleeding and to confirm that the balloon remained correctly positioned without prolapse. Ultrasound guidance was not routinely used to verify the final position of the balloon. In the Bakri group, prophylactic vaginal gauze packing was applied to help prevent balloon prolapse. The balloon was routinely removed on the morning of the first postoperative day. Primary and secondary outcomes The primary outcome was balloon failure, defined as inadequate postoperative bleeding control despite balloon tamponade, necessitating additional interventions such as allogeneic blood transfusion, uterine artery embolization, or further surgical procedures to achieve hemostasis. Cases involving only autologous blood transfusion were excluded from the transfusion category. This composite endpoint was selected to capture clinically meaningful escalation in postoperative hemostatic management rather than isolated surrogate measures. The secondary outcomes included an evaluation of the balloon placement procedure, including insertion time, postoperative blood loss, the overall incidence of balloon prolapse, and any infectious or insertion-related complications attributable to balloon placement. Balloon prolapse was defined as postoperative displacement of the uterine balloon from its intended position, regardless of whether hemostatic control was maintained after displacement. Insertion time was defined as the duration from balloon preparation to completion of its placement, measured retrospectively based on surgical video recordings. Statistical analysis Continuous variables are presented as median (range), and categorical variables as number (%). The Mann–Whitney U test was applied to continuous variables, and Fisher’s exact test was applied to categorical variables, as appropriate. Two-sided p-values < 0.05 were considered statistically significant. All analyses were conducted using R software (version 4.3.1; R Foundation for Statistical Computing, Vienna, Austria). Results Profile of patients who underwent intrauterine balloon tamponade During the six-year study period, a total of 100 cesarean deliveries for placenta previa or low-lying placenta were performed at Kanazawa University Hospital. Intrauterine balloon tamponade was applied in 47 of these cases: 20 patients in the OB group and 27 in the Bakri group. Patient characteristics are summarized in Table 1 . No statistically significant differences were observed in baseline characteristics between the two groups, and balloon insertion time did not differ significantly between the OB and Bakri groups. Table 1 Patient characteristics in the OB and Bakri groups Variable OB group (n = 20) Bakri group (n = 27) P-value Age (years) 38 (25–43) 34 (25–41) 0.128 Gestational age (weeks) 37.0 (33.6–37.9) 37.1 (36.6–37.9) 0.650 Parity 0.244 └ Nulliparous 8 16 └ Multiparous 12 11 History of cesarean section 0.119 └ None 15 25 └ Present 5 2 Placenta type 0.767 └ Low-lying placenta 7 11 └ Placenta previa 13 16 └ Complete 7 9 └ Partial/marginal 6 7 Placental position 0.524 └ Anterior 0 2 └ Posterior 19 22 └ Other* 1 3 Placenta accreta Spectrum (PAS) 0.638 └ None 17 25 └ Accreta 3 2 └ Increta 0 0 └ Percreta 0 0 Conception method 1.000 └ Natural conception 13 17 └ Assisted reproductive technology 7 10 Timing of cesarean section 0.127 └ Elective 10 20 └ Emergency 10 7 Operative time (minutes) 61 (41–80) 61 (31–121) 0.830 Intraoperative blood loss (mL) 875 (310–2940) 990 (400–2580) 0.237 Balloon indwelling time (hours) 22.6 (14.8–27.6) 22.8 (14.2–31.2) 0.328 Balloon insertion time (seconds) 152 (72–225) 119 (36–540) 0.098 Values are presented as median (minimum–maximum) or n (%). * Other includes fundal, lateral, or circumferential placentas in which the anterior or posterior position could not be clearly determined. Balloon failure in the Bakri and OB groups Table 2 summarizes the cases of balloon failure. Postoperative bleeding was adequately controlled in all OB group cases. In contrast, all five cases of inadequate bleeding control in the Bakri group were consistently associated with balloon prolapse. Among these, four required balloon reinsertion to achieve hemostasis, and two required additional allogeneic transfusion. Postoperative balloon prolapse occurred in six cases (22.2%) in the Bakri group, whereas none occurred in the OB group. Of the six prolapse events, one was identified in the operating room, four were detected shortly after the patients returned to the ward, and the remaining case was noted the following day during planned balloon removal, with hemostatic control maintained. There were no statistically significant differences in postoperative blood loss between the two groups. Three OB cases and two Bakri cases were suspected of placenta accreta and required manual placental removal; however, no balloon failures occurred. No infections or insertion-related complications attributable to balloon placement were observed in either group during the initial hospitalization. Additionally, no inadvertent balloon punctures or damage during myometrial closure were reported. Table 2 Balloon failure and postoperative blood loss in the OB and Bakri groups Variable OB group (n = 20) Bakri group (n = 27) P-value Cases with balloon failure 0 5 (18.5%) 0.063 └ Balloon prolapse 0 5/5 └ Balloon reinsertion due to prolapse 0 4/5 └ Allogeneic transfusion 0 2/5 └Uterine artery embolization (UAE) 0 0 └ Surgical intervention 0 0 Overall cases of balloon prolapse 0 6 (22.2%) 0.031* Postoperative blood loss └ Within 2 hours after surgery (mL) 49 (0–182) 40 (0–1298) 0.714 └ From end of surgery to balloon removal (mL) 112 (25–500) 124 (40–1798) 0.451 Values are presented as median (minimum–maximum) or n (%). Discussion Principal findings In this study, the OB balloon was associated with improved postoperative hemorrhage control and a lower incidence of balloon prolapse compared with the conventional Bakri balloon in cesarean deliveries for placenta previa and low-lying placenta. Results in the context of what is known The incidence of abnormal placental positioning, such as placenta previa and low-lying placenta, has been reported to be increasing in recent years, likely owing to the rising rates of cesarean delivery and the expanded use of assisted reproductive technologies [ 5 , 6 ]. These conditions are frequently accompanied by massive hemorrhage during and after cesarean delivery, and conventional hemostatic methods may not always provide sufficient bleeding control. Even when balloon tamponade is used prophylactically, inadequate hemostasis may necessitate balloon reinsertion or UAE [ 7 ]. The reported success rate of Bakri balloon tamponade for hemostasis in cesarean delivery is approximately 81.7% [ 8 ]. The Bakri balloon features a single-balloon design that compresses the lower uterine segment, rendering it susceptible to prolapse into the vaginal canal due to gravity and uterine contractions. Several adjunctive techniques have been proposed to prevent prolapse, including cervical clamping or the use of a Nelaton catheter for stabilization [ 9 , 10 ]. In contrast, the OB balloon incorporates a double-balloon design, with the vaginal balloon unaffected by uterine contractions, thereby preventing prolapse. Furthermore, the standardized insertion protocol involves initial inflation of the vaginal balloon followed by gentle traction to confirm that it reaches the level of the vaginal canal, ensuring sufficient diameter for secure anchorage. Subsequently, the uterine balloon is inflated. This stepwise approach creates a sandwich-like configuration, positioning the cervix between two balloons, which likely contributes to the reduced prolapse rate observed with the OB balloon. In our study, Bakri balloon prolapses frequently required reinsertion or additional allogeneic transfusion, whereas no prolapse cases occurred in the OB group. These findings suggest that the OB balloon’s design for prolapse prevention may offer clinical advantages for postoperative hemostatic stability. Published case reports have described uterine perforation and extrauterine migration associated with the Bakri balloon. These events have predominantly occurred during transvaginal insertion for postpartum hemorrhage management, even when performed under ultrasound guidance [ 11 – 13 ]. In our cohort, in which both Bakri and OB balloons were inserted intraoperatively through the uterine incision, no uterine perforations occurred in either group. From a technical perspective, intraoperative insertion through the uterine incision under direct visualization may reduce the risk of perforation compared with blind transvaginal insertion. However, these potential benefits remain theoretical in our study owing to the limited sample size. Therefore, meticulous attention to insertion technique and postoperative monitoring remains essential whenever intrauterine balloon tamponade is employed. Clinical implications The OB balloon offers clear advantages for achieving proper placement during cesarean delivery. Unlike other double-balloon devices [ 14 , 15 ], the OB balloon features an inflation connector accessible from the operative field, allowing intraoperative adjustment. Furthermore, if postoperative uterine bleeding occurs, the uterine balloon can be additionally inflated via the vaginal-side connector. These characteristics make the OB balloon a simple, effective, and reliable option for preventing prolapse and achieving hemostasis in high-risk cesarean deliveries. Research implications It is essential that future prospective, multicenter studies with larger sample sizes be conducted to confirm the observed reductions in balloon prolapse and inadequate postoperative bleeding control associated with the OB balloon. Such studies would also enable evaluation of the generalizability of these findings. The implementation of randomized or quasi-experimental study designs would help minimize confounding related to temporal changes in institutional practice. Further research is warranted to determine the optimal indications and timing for OB balloon use, including its potential role in postpartum hemorrhage caused by etiologies other than abnormal placentation. Strengths and limitations One strength of this study is that two different types of balloons were used during distinct, non-overlapping time periods, which reduces the potential for selection bias related to operator preference. In addition, no cases of prolapse were observed in the OB group, regardless of operator experience, suggesting that the OB balloon can be used safely and effectively even by first-time operators in routine clinical practice. A potential limitation of the OB balloon is its fixed position between the uterine and vaginal compartments, which may restrict its ability to control bleeding originating above the internal cervical os, particularly in the uterine corpus and fundus. We speculate that in cases where the uterine cavity is distorted by fibroids, or when bleeding results from retained placenta, adequate compression may be difficult to achieve with the OB balloon. In such instances, Bakri balloons or other interventions, such as uterine compression sutures (e.g., B-Lynch), may remain effective treatment options [ 8 , 16 , 17 ]. This study has several limitations. First, it was a single-center, retrospective study with a small sample size. Because the OB group was treated more recently than the Bakri group, unmeasured temporal variations in clinical practice and perioperative management—as well as differences in surgeon experience with balloon placement and inflation—may have influenced the observed differences between the two groups. The limited number of primary outcome events also constrained the statistical power and precision of the estimated effect sizes. Second, the decision to use an intrauterine balloon and to perform additional hemostatic procedures was left to the discretion of the attending obstetrician. Balloons were occasionally applied prophylactically in cases considered at high risk for hemorrhage, and in some instances, hemostasis might have been achievable without balloon use. These individualized decisions introduce potential selection bias and may limit the generalizability of our findings. Finally, the Bakri balloon prolapse rate (18.5%) in this study was higher than previously reported rates of 6–16% [ 18 ], and a separate Japanese single-center study reported a rate of 11% [ 7 ]. This discrepancy suggests that the higher rate observed here may reflect technical or operator-specific factors unique to our institution, in addition to the limited sample size. Conclusion This study provides the first clinical evidence supporting the safety and efficacy of the OB balloon. These findings make an important contribution to the field of obstetric hemostasis. Future prospective, multicenter studies—including prophylactic use in cases of placenta previa—are warranted to establish higher-level evidence and validate these preliminary findings. Declarations Ethics approval and consent to participate This study was approved by the Ethics Committee of Kanazawa University School of Medicine (approval number: 2023-063,114329). The requirement for written informed consent was waived owing to the retrospective design of the study. Competing Interests Dr. Tanaka has been involved in the development of the OB balloon device used in this study. Funding sources The authors received no specific funding for this research. Author Contribution Iwao Yasoshima and Takashi Iizuka drafted the manuscript. Kaoru Abiko critically revised the manuscript. Nao Hoshiba, Kyosuke Kagami, and Masaaki Tanaka collected the data and interpreted the patient data regarding obstetric and gynecological aspects. Kaoru Abiko supervised the study. All authors contributed to the study conception and were involved in the revision and final approval of the manuscript. Data Availability The data supporting the findings of this study are available from the corresponding author, T.I., upon reasonable request. References Nor AM, Jagdeesh K, Mohd FAS, Kamraul AK, Yusmadi A, Noraslawati R, et al. Peripartum hysterectomy clinical characteristics and outcomes: a hospital-based retrospective audit study. Med J Malaysia. 2023;78:756–62. Corbetta-Rastelli CM, Friedman AM, Sobhani NC, Arditi B, Goffman D, Wen T. Postpartum hemorrhage trends and outcomes in the United States, 2000–2019. Obstet Gynecol. 2023;141:152–61. Overton E, D’Alton M, Goffman D. Intrauterine devices in the management of postpartum hemorrhage. Am J Obstet Gynecol. 2024;230:S1076–88. Gibier M, Pauly V, Orleans V, Fabre C, Boyer L, Blanc J. Risk factors for intrauterine tamponade failure in postpartum hemorrhage. Obstet Gynecol. 2022;140:439–46. Landsverk E, Berntsen S, Magnussen EB, Åsvold BO, Romundstad LB. Risk of placenta previa in assisted reproductive technology: a Nordic population study with sibling analyses. PLOS Med. 2024;21:e1004536. AlQasem MH, Shaamash AH, Ghamdi DSA, Mahfouz AA, Eskandar MA. Incidence, risk factors, and maternal outcomes of major degree placenta previa: a 10-year retrospective analysis. Saudi Med J. 2023;44:912–20. Soyama H, Miyamoto M, Ishibashi H, Nakatsuka M, Kawauchi H, Sakamoto T, et al. Analysis of prophylactic Bakri balloon tamponade failure in patients with placenta previa. Taiwan J Obstet Gynecol. 2019;58:159–63. Suarez S, Conde-Agudelo A, Borovac-Pinheiro A, Suarez-Rebling D, Eckardt M, Theron G, et al. Uterine balloon tamponade for the treatment of postpartum hemorrhage: a systematic review and meta-analysis. Am J Obstet Gynecol. 2020;222:e2931–29352. Yang H, Sun G, Cheng Y, Cao D, Zhao Y. Bakri balloon tamponade to treat postpartum hemorrhage. Chin Med J (Engl). 2022;135:2258–60. Takahashi H, Baba Y, Usui R, Ohkuchi A, Matsubara S. Video image: Matsubara’s Nelaton and Fishing methods for easier Bakri balloon insertion and avoiding its prolapse during cesarean section. Hypertens Res Pregnancy. 2018;6:73–5. Leparco S, Viot A, Benachi A, Deffieux X. Migration of Bakri balloon through an unsuspected uterine perforation during the treatment of secondary postpartum hemorrhage. Am J Obstet Gynecol. 2013;208:e6–7. Rocher G, Panel P, Rollin I, Wormser A, Souiai-Hidoussi A, Raynal P, et al. Massive hemoperitoneum due to uterine perforation by the Bakri Balloon, during the treatment of postpartum hemorrhage. J Gynecol Obstet Hum Reprod. 2019;48:75–6. Spencer NR, Saad A. Perforation with Bakri balloon into broad ligament during management of postpartum hemorrhage. Am J Obstet Gynecol. 2021;224:227. Dildy GA, Belfort MA, Adair CD, Destefano K, Robinson D, Lam G, et al. Initial experience with a dual-balloon catheter for the management of postpartum hemorrhage. Am J Obstet Gynecol. 2014;210:e1361–6. Barinov SV, Medyannikova IV, Borisova AV, Tyrskaya YI, Savelieva IV, Shamina IV, et al. The usefulness of Zhukovsky Double Balloon in obstetric hemorrhage. J Matern Fetal Med. 2019;1:10–7. Barik A, Singh V, Choudhary A, Yadav P. Central placenta previa with coexisting central cervical fibroid in pregnancy: an obstetrician’s nightmare. Cureus. 2021;13:e15910. Brown H, Okeyo S, Mabeya H, Wilkinson J, Schmitt J. The Bakri tamponade balloon as an adjunct treatment for refractory postpartum hemorrhage. Int J Gynaecol Obstet. 2016;135:276–80. Wright CE, Chauhan SP, Abuhamad AZ. Bakri balloon in the management of postpartum hemorrhage: a review. Am J Perinatol. 2014;31:957–64. Additional Declarations Competing interest reported. Dr. Tanaka has been involved in the development of the OB balloon device used in this study. Cite Share Download PDF Status: Published Journal Publication published 04 Feb, 2026 Read the published version in BMC Pregnancy and Childbirth → Version 1 posted Editorial decision: Revision requested 05 Jan, 2026 Reviews received at journal 23 Dec, 2025 Reviews received at journal 14 Dec, 2025 Reviewers agreed at journal 11 Dec, 2025 Reviewers agreed at journal 06 Dec, 2025 Reviewers invited by journal 06 Dec, 2025 Submission checks completed at journal 02 Dec, 2025 First submitted to journal 02 Dec, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7147446","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":554096173,"identity":"99d2ac83-9987-4dbe-bf7e-17c299e2ab8b","order_by":0,"name":"Iwao Yasoshima","email":"","orcid":"","institution":"Kanazawa University","correspondingAuthor":false,"prefix":"","firstName":"Iwao","middleName":"","lastName":"Yasoshima","suffix":""},{"id":554096174,"identity":"02d16a08-9dbf-41ea-ae4d-6660d46b8da9","order_by":1,"name":"Nao Hoshiba","email":"","orcid":"","institution":"Toyama Prefectural Central 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1","display":"","copyAsset":false,"role":"figure","size":1018285,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSchematic representation of the OB balloon and its application during cesarean delivery.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eA: \u003c/strong\u003ePhotograph of the OB balloon device.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eB: \u003c/strong\u003eSchematic illustration showing cervical compression achieved through the double-balloon design.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eC:\u003c/strong\u003e Location of the inflation connectors and deflation mechanism.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eD–F: \u003c/strong\u003eStepwise depiction of OB balloon placement during cesarean delivery: (D) insertion through the uterine incision, (E) inflation of the vaginal and intrauterine balloons, and (F) final position showing the cervix compressed between the two balloons before uterine closure.\u003c/p\u003e","description":"","filename":"Figurerev4.png","url":"https://assets-eu.researchsquare.com/files/rs-7147446/v1/219a61a3c4c943f92b09cd89.png"},{"id":102234374,"identity":"8044fda5-4ed3-4ecf-b9f9-d08d2eb4d7aa","added_by":"auto","created_at":"2026-02-09 16:10:47","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2286864,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7147446/v1/ba3cb5c1-d6ae-4efa-b60f-f3c022117c6e.pdf"}],"financialInterests":"Competing interest reported. Dr. Tanaka has been involved in the development of the OB balloon device used in this study.","formattedTitle":"Efficacy of OB Balloon Tamponade in Cesarean Delivery for Placenta Previa and Low-Lying Placenta: A Retrospective Comparative Study","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePlacenta previa and low-lying placenta are abnormal placental implantations associated with substantial maternal and perinatal complications, particularly postpartum hemorrhage, which remains a leading cause of maternal mortality worldwide [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. During cesarean delivery in such cases, effective hemorrhage control is crucial. Available techniques include intrauterine balloon tamponade, uterine compression sutures, arterial ligation, and resuscitative endovascular balloon occlusion of the aorta, with hysterectomy reserved as a last resort for uncontrolled bleeding [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Intrauterine balloon tamponade is a simple and effective method for managing postpartum hemorrhage; however, the balloon may prolapse into the vagina, resulting in inadequate hemostasis [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eDr. Tanaka, a co-author of this study, developed the OB balloon\u0026mdash;a novel double-balloon catheter for uterine tamponade that was commercialized in Japan in 2022 (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA). The intrauterine balloon is positioned in the lower uterine segment, while the vaginal balloon is placed within the vaginal cavity to compress the cervix from both sides, thereby preventing prolapse of the intrauterine balloon into the vagina (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eB). The term \u0026ldquo;OB\u0026rdquo; is derived from \u0026ldquo;obstetrics\u0026rdquo; and \u0026ldquo;obstruction\u0026rdquo; and serves as the product name \u0026ldquo;OB balloon,\u0026rdquo; emphasizing the device\u0026rsquo;s function in controlling obstetric hemorrhage. A distinctive feature of the OB balloon is that the primary connectors are located on the uterine side, allowing intraoperative adjustment of the inflation volumes of both balloons within the surgical field (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eC). Postoperatively, the intrauterine balloon inflation can also be modified via an additional vaginal-side connector. The device is commercially available in Japan and has been adopted by multiple institutions. According to the manufacturer\u0026rsquo;s instructions, the intrauterine and vaginal balloons can be filled with up to 500 mL and 100 mL of fluid, respectively, although the attending obstetrician adjusts these volumes to achieve adequate compression in each case. The OB balloon placement procedure is illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eD\u0026ndash;F.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe objective of this study was to compare the efficacy and performance of the OB balloon with the conventional Bakri\u0026reg; Postpartum Balloon during cesarean deliveries for placenta previa and low-lying placenta.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStudy design and population\u003c/h2\u003e\u003cp\u003eThis single-institution, retrospective study included all cesarean deliveries for placenta previa or low-lying placenta performed between January 2019 and December 2024. The study period was defined to encompass cases occurring both before and after the introduction of the OB balloon. We included cases in which intrauterine balloon tamponade was performed intraoperatively using either the OB balloon (OB group) or the Bakri balloon (Bakri group). At our institution, Bakri balloons were primarily used until October 2022, and OB balloons were predominantly employed from November 2022 onward, resulting in two historical control groups without temporal overlap in balloon use. The OB balloon was approved for clinical use in Japan in November 2022 and has since been incorporated into routine obstetric practice at our institution as one of the standard options for intrauterine balloon tamponade. Cases were excluded if no intrauterine balloon was used, insertion failed because of placement difficulty, a balloon other than the OB or Bakri type was used, or a planned peripartum hysterectomy was performed for placenta accreta spectrum (PAS).\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eData collection\u003c/h3\u003e\n\u003cp\u003eClinical data were retrospectively extracted from electronic medical records at Kanazawa University Hospital. For all cesarean deliveries performed for placenta previa or low-lying placenta during the study period, we collected information on maternal demographics, obstetric history, gestational age at delivery, placenta type and position, timing of cesarean section (elective or emergency), operative time, and intraoperative blood loss. Complete placenta previa was defined as placental tissue covering the internal cervical os, whereas partial or marginal placenta previa was defined as the placental edge reaching but not covering the internal cervical os. Low-lying placenta was defined as the placental edge located within 20 mm of the internal cervical os. Placental position was categorized as anterior, posterior, or other. The latter category included fundal, lateral, or circumferential placentas in which the anterior or posterior location could not be clearly determined. For cases in which intrauterine balloon tamponade was used, additional procedure-related variables were collected, including balloon type (OB or Bakri), insertion time, indwelling duration, and postoperative blood loss measured within 2 hours after surgery as well as from the end of surgery until balloon removal. The presence of placenta accreta spectrum was also assessed. Postoperative outcomes were systematically recorded, including balloon prolapse, balloon reinsertion, transfusion, uterine artery embolization (UAE), additional surgical procedures, and postoperative complications such as infection or insertion-related injury. The timing of balloon prolapse events was documented as well.\u003c/p\u003e\n\u003ch3\u003eBalloon insertion procedures\u003c/h3\u003e\n\u003cp\u003eThe balloon was placed intraoperatively at the discretion of the attending obstetrician when active bleeding, including persistent oozing, was observed after delivery of the fetus and placenta. In both groups, the attending obstetrician determined the indication for balloon placement and its final position, and the insertion procedure was standardized according to the institutional protocol. In the OB group, the balloon was inserted intraoperatively from the operative field by either the operating surgeon or the first assistant. After insertion, the vaginal balloon was inflated, and gentle traction was applied to confirm adequate expansion and fixation at the level of the vaginal canal. Subsequently, the uterine balloon was inflated under direct visualization within the surgical field. In the Bakri group, the balloon was inserted and positioned by either the operating surgeon or the first assistant, and inflation was performed by the second assistant from the vaginal side, outside the surgical field. Thus, the main difference between the two devices was not a fundamental difference in insertion technique but rather who performed the balloon inflation and where it occurred\u0026mdash;in the operative field or from the vaginal side. At our institution, uterine muscle repair is typically performed using continuous two-layer barbed suturing. However, when an intrauterine balloon is placed, the uterine incision is closed with non-barbed, single-layer interrupted sutures in accordance with our institutional protocol. This modification is implemented to minimize the risk of inadvertent needle injury to the balloon. Postoperatively, a vaginal examination was performed to assess for active bleeding and to confirm that the balloon remained correctly positioned without prolapse. Ultrasound guidance was not routinely used to verify the final position of the balloon. In the Bakri group, prophylactic vaginal gauze packing was applied to help prevent balloon prolapse. The balloon was routinely removed on the morning of the first postoperative day.\u003c/p\u003e\n\u003ch3\u003ePrimary and secondary outcomes\u003c/h3\u003e\n\u003cp\u003eThe primary outcome was balloon failure, defined as inadequate postoperative bleeding control despite balloon tamponade, necessitating additional interventions such as allogeneic blood transfusion, uterine artery embolization, or further surgical procedures to achieve hemostasis. Cases involving only autologous blood transfusion were excluded from the transfusion category. This composite endpoint was selected to capture clinically meaningful escalation in postoperative hemostatic management rather than isolated surrogate measures.\u003c/p\u003e\u003cp\u003eThe secondary outcomes included an evaluation of the balloon placement procedure, including insertion time, postoperative blood loss, the overall incidence of balloon prolapse, and any infectious or insertion-related complications attributable to balloon placement. Balloon prolapse was defined as postoperative displacement of the uterine balloon from its intended position, regardless of whether hemostatic control was maintained after displacement. Insertion time was defined as the duration from balloon preparation to completion of its placement, measured retrospectively based on surgical video recordings.\u003c/p\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eContinuous variables are presented as median (range), and categorical variables as number (%). The Mann\u0026ndash;Whitney U test was applied to continuous variables, and Fisher\u0026rsquo;s exact test was applied to categorical variables, as appropriate. Two-sided p-values\u0026thinsp;\u0026lt;\u0026thinsp;0.05 were considered statistically significant. All analyses were conducted using R software (version 4.3.1; R Foundation for Statistical Computing, Vienna, Austria).\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003eProfile of patients who underwent intrauterine balloon tamponade\u003c/h2\u003e\u003cp\u003eDuring the six-year study period, a total of 100 cesarean deliveries for placenta previa or low-lying placenta were performed at Kanazawa University Hospital. Intrauterine balloon tamponade was applied in 47 of these cases: 20 patients in the OB group and 27 in the Bakri group. Patient characteristics are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. No statistically significant differences were observed in baseline characteristics between the two groups, and balloon insertion time did not differ significantly between the OB and Bakri groups.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003ePatient characteristics in the OB and Bakri groups\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVariable\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eOB group (n\u0026thinsp;=\u0026thinsp;20)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eBakri group (n\u0026thinsp;=\u0026thinsp;27)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eP-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge (years)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e38 (25\u0026ndash;43)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e34 (25\u0026ndash;41)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.128\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGestational age (weeks)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e37.0 (33.6\u0026ndash;37.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e37.1 (36.6\u0026ndash;37.9)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.650\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.244\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Nulliparous\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Multiparous\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHistory of cesarean section\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.119\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ None\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Present\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePlacenta type\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.767\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Low-lying placenta\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Placenta previa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Complete\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Partial/marginal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePlacental position\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.524\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Anterior\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Posterior\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Other*\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePlacenta accreta Spectrum (PAS)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.638\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ None\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Accreta\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Increta\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Percreta\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eConception method\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.000\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Natural conception\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Assisted reproductive technology\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTiming of cesarean section\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.127\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Elective\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Emergency\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOperative time (minutes)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e61 (41\u0026ndash;80)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e61 (31\u0026ndash;121)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.830\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eIntraoperative blood loss (mL)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e875 (310\u0026ndash;2940)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e990 (400\u0026ndash;2580)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.237\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBalloon indwelling time (hours)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e22.6 (14.8\u0026ndash;27.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e22.8 (14.2\u0026ndash;31.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.328\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBalloon insertion time (seconds)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e152 (72\u0026ndash;225)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e119 (36\u0026ndash;540)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.098\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003eValues are presented as median (minimum\u0026ndash;maximum) or n (%).\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003e* Other includes fundal, lateral, or circumferential placentas in which the anterior or posterior position could not be clearly determined.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eBalloon failure in the Bakri and OB groups\u003c/h3\u003e\n\u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e summarizes the cases of balloon failure. Postoperative bleeding was adequately controlled in all OB group cases. In contrast, all five cases of inadequate bleeding control in the Bakri group were consistently associated with balloon prolapse. Among these, four required balloon reinsertion to achieve hemostasis, and two required additional allogeneic transfusion. Postoperative balloon prolapse occurred in six cases (22.2%) in the Bakri group, whereas none occurred in the OB group. Of the six prolapse events, one was identified in the operating room, four were detected shortly after the patients returned to the ward, and the remaining case was noted the following day during planned balloon removal, with hemostatic control maintained. There were no statistically significant differences in postoperative blood loss between the two groups. Three OB cases and two Bakri cases were suspected of placenta accreta and required manual placental removal; however, no balloon failures occurred. No infections or insertion-related complications attributable to balloon placement were observed in either group during the initial hospitalization. Additionally, no inadvertent balloon punctures or damage during myometrial closure were reported.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eBalloon failure and postoperative blood loss in the OB and Bakri groups\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVariable\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eOB group\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;20)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eBakri group\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;27)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eP-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCases with balloon failure\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5 (18.5%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.063\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Balloon prolapse\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5/5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Balloon reinsertion due to prolapse\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4/5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Allogeneic transfusion\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2/5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└Uterine artery embolization (UAE)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Surgical intervention\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOverall cases of balloon prolapse\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6 (22.2%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.031*\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePostoperative blood loss\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ Within 2 hours after surgery (mL)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e49 (0\u0026ndash;182)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e40 (0\u0026ndash;1298)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.714\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e└ From end of surgery to balloon removal (mL)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e112 (25\u0026ndash;500)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e124 (40\u0026ndash;1798)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.451\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003eValues are presented as median (minimum\u0026ndash;maximum) or n (%).\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003ePrincipal findings\u003c/h2\u003e\u003cp\u003eIn this study, the OB balloon was associated with improved postoperative hemorrhage control and a lower incidence of balloon prolapse compared with the conventional Bakri balloon in cesarean deliveries for placenta previa and low-lying placenta.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003eResults in the context of what is known\u003c/h2\u003e\u003cp\u003eThe incidence of abnormal placental positioning, such as placenta previa and low-lying placenta, has been reported to be increasing in recent years, likely owing to the rising rates of cesarean delivery and the expanded use of assisted reproductive technologies [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. These conditions are frequently accompanied by massive hemorrhage during and after cesarean delivery, and conventional hemostatic methods may not always provide sufficient bleeding control. Even when balloon tamponade is used prophylactically, inadequate hemostasis may necessitate balloon reinsertion or UAE [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe reported success rate of Bakri balloon tamponade for hemostasis in cesarean delivery is approximately 81.7% [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. The Bakri balloon features a single-balloon design that compresses the lower uterine segment, rendering it susceptible to prolapse into the vaginal canal due to gravity and uterine contractions. Several adjunctive techniques have been proposed to prevent prolapse, including cervical clamping or the use of a Nelaton catheter for stabilization [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. In contrast, the OB balloon incorporates a double-balloon design, with the vaginal balloon unaffected by uterine contractions, thereby preventing prolapse. Furthermore, the standardized insertion protocol involves initial inflation of the vaginal balloon followed by gentle traction to confirm that it reaches the level of the vaginal canal, ensuring sufficient diameter for secure anchorage. Subsequently, the uterine balloon is inflated. This stepwise approach creates a sandwich-like configuration, positioning the cervix between two balloons, which likely contributes to the reduced prolapse rate observed with the OB balloon. In our study, Bakri balloon prolapses frequently required reinsertion or additional allogeneic transfusion, whereas no prolapse cases occurred in the OB group. These findings suggest that the OB balloon\u0026rsquo;s design for prolapse prevention may offer clinical advantages for postoperative hemostatic stability.\u003c/p\u003e\u003cp\u003ePublished case reports have described uterine perforation and extrauterine migration associated with the Bakri balloon. These events have predominantly occurred during transvaginal insertion for postpartum hemorrhage management, even when performed under ultrasound guidance [\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. In our cohort, in which both Bakri and OB balloons were inserted intraoperatively through the uterine incision, no uterine perforations occurred in either group. From a technical perspective, intraoperative insertion through the uterine incision under direct visualization may reduce the risk of perforation compared with blind transvaginal insertion. However, these potential benefits remain theoretical in our study owing to the limited sample size. Therefore, meticulous attention to insertion technique and postoperative monitoring remains essential whenever intrauterine balloon tamponade is employed.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003eClinical implications\u003c/h2\u003e\u003cp\u003eThe OB balloon offers clear advantages for achieving proper placement during cesarean delivery. Unlike other double-balloon devices [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], the OB balloon features an inflation connector accessible from the operative field, allowing intraoperative adjustment. Furthermore, if postoperative uterine bleeding occurs, the uterine balloon can be additionally inflated via the vaginal-side connector. These characteristics make the OB balloon a simple, effective, and reliable option for preventing prolapse and achieving hemostasis in high-risk cesarean deliveries.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\u003ch2\u003eResearch implications\u003c/h2\u003e\u003cp\u003eIt is essential that future prospective, multicenter studies with larger sample sizes be conducted to confirm the observed reductions in balloon prolapse and inadequate postoperative bleeding control associated with the OB balloon. Such studies would also enable evaluation of the generalizability of these findings. The implementation of randomized or quasi-experimental study designs would help minimize confounding related to temporal changes in institutional practice. Further research is warranted to determine the optimal indications and timing for OB balloon use, including its potential role in postpartum hemorrhage caused by etiologies other than abnormal placentation.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\u003ch2\u003eStrengths and limitations\u003c/h2\u003e\u003cp\u003eOne strength of this study is that two different types of balloons were used during distinct, non-overlapping time periods, which reduces the potential for selection bias related to operator preference. In addition, no cases of prolapse were observed in the OB group, regardless of operator experience, suggesting that the OB balloon can be used safely and effectively even by first-time operators in routine clinical practice.\u003c/p\u003e\u003cp\u003eA potential limitation of the OB balloon is its fixed position between the uterine and vaginal compartments, which may restrict its ability to control bleeding originating above the internal cervical os, particularly in the uterine corpus and fundus. We speculate that in cases where the uterine cavity is distorted by fibroids, or when bleeding results from retained placenta, adequate compression may be difficult to achieve with the OB balloon. In such instances, Bakri balloons or other interventions, such as uterine compression sutures (e.g., B-Lynch), may remain effective treatment options [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThis study has several limitations. First, it was a single-center, retrospective study with a small sample size. Because the OB group was treated more recently than the Bakri group, unmeasured temporal variations in clinical practice and perioperative management\u0026mdash;as well as differences in surgeon experience with balloon placement and inflation\u0026mdash;may have influenced the observed differences between the two groups. The limited number of primary outcome events also constrained the statistical power and precision of the estimated effect sizes.\u003c/p\u003e\u003cp\u003eSecond, the decision to use an intrauterine balloon and to perform additional hemostatic procedures was left to the discretion of the attending obstetrician. Balloons were occasionally applied prophylactically in cases considered at high risk for hemorrhage, and in some instances, hemostasis might have been achievable without balloon use. These individualized decisions introduce potential selection bias and may limit the generalizability of our findings.\u003c/p\u003e\u003cp\u003eFinally, the Bakri balloon prolapse rate (18.5%) in this study was higher than previously reported rates of 6\u0026ndash;16% [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], and a separate Japanese single-center study reported a rate of 11% [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. This discrepancy suggests that the higher rate observed here may reflect technical or operator-specific factors unique to our institution, in addition to the limited sample size.\u003c/p\u003e\u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study provides the first clinical evidence supporting the safety and efficacy of the OB balloon. These findings make an important contribution to the field of obstetric hemostasis. Future prospective, multicenter studies\u0026mdash;including prophylactic use in cases of placenta previa\u0026mdash;are warranted to establish higher-level evidence and validate these preliminary findings.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003ch2\u003eEthics approval and consent to participate\u003c/h2\u003e\u003cp\u003eThis study was approved by the Ethics Committee of Kanazawa University School of Medicine (approval number: 2023-063,114329). The requirement for written informed consent was waived owing to the retrospective design of the study.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003cp\u003eDr. Tanaka has been involved in the development of the OB balloon device used in this study.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eFunding sources\u003c/h2\u003e\u003cp\u003eThe authors received no specific funding for this research.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eIwao Yasoshima and Takashi Iizuka drafted the manuscript. Kaoru Abiko critically revised the manuscript. Nao Hoshiba, Kyosuke Kagami, and Masaaki Tanaka collected the data and interpreted the patient data regarding obstetric and gynecological aspects. Kaoru Abiko supervised the study. All authors contributed to the study conception and were involved in the revision and final approval of the manuscript.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe data supporting the findings of this study are available from the corresponding author, T.I., upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eNor AM, Jagdeesh K, Mohd FAS, Kamraul AK, Yusmadi A, Noraslawati R, et al. Peripartum hysterectomy clinical characteristics and outcomes: a hospital-based retrospective audit study. Med J Malaysia. 2023;78:756\u0026ndash;62.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCorbetta-Rastelli CM, Friedman AM, Sobhani NC, Arditi B, Goffman D, Wen T. Postpartum hemorrhage trends and outcomes in the United States, 2000\u0026ndash;2019. Obstet Gynecol. 2023;141:152\u0026ndash;61.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOverton E, D\u0026rsquo;Alton M, Goffman D. Intrauterine devices in the management of postpartum hemorrhage. Am J Obstet Gynecol. 2024;230:S1076\u0026ndash;88.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGibier M, Pauly V, Orleans V, Fabre C, Boyer L, Blanc J. Risk factors for intrauterine tamponade failure in postpartum hemorrhage. Obstet Gynecol. 2022;140:439\u0026ndash;46.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLandsverk E, Berntsen S, Magnussen EB, \u0026Aring;svold BO, Romundstad LB. Risk of placenta previa in assisted reproductive technology: a Nordic population study with sibling analyses. PLOS Med. 2024;21:e1004536.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAlQasem MH, Shaamash AH, Ghamdi DSA, Mahfouz AA, Eskandar MA. Incidence, risk factors, and maternal outcomes of major degree placenta previa: a 10-year retrospective analysis. Saudi Med J. 2023;44:912\u0026ndash;20.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSoyama H, Miyamoto M, Ishibashi H, Nakatsuka M, Kawauchi H, Sakamoto T, et al. Analysis of prophylactic Bakri balloon tamponade failure in patients with placenta previa. Taiwan J Obstet Gynecol. 2019;58:159\u0026ndash;63.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSuarez S, Conde-Agudelo A, Borovac-Pinheiro A, Suarez-Rebling D, Eckardt M, Theron G, et al. Uterine balloon tamponade for the treatment of postpartum hemorrhage: a systematic review and meta-analysis. Am J Obstet Gynecol. 2020;222:e2931\u0026ndash;29352.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYang H, Sun G, Cheng Y, Cao D, Zhao Y. Bakri balloon tamponade to treat postpartum hemorrhage. Chin Med J (Engl). 2022;135:2258\u0026ndash;60.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTakahashi H, Baba Y, Usui R, Ohkuchi A, Matsubara S. Video image: Matsubara\u0026rsquo;s Nelaton and Fishing methods for easier Bakri balloon insertion and avoiding its prolapse during cesarean section. Hypertens Res Pregnancy. 2018;6:73\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLeparco S, Viot A, Benachi A, Deffieux X. Migration of Bakri balloon through an unsuspected uterine perforation during the treatment of secondary postpartum hemorrhage. Am J Obstet Gynecol. 2013;208:e6\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRocher G, Panel P, Rollin I, Wormser A, Souiai-Hidoussi A, Raynal P, et al. Massive hemoperitoneum due to uterine perforation by the Bakri Balloon, during the treatment of postpartum hemorrhage. J Gynecol Obstet Hum Reprod. 2019;48:75\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSpencer NR, Saad A. Perforation with Bakri balloon into broad ligament during management of postpartum hemorrhage. Am J Obstet Gynecol. 2021;224:227.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDildy GA, Belfort MA, Adair CD, Destefano K, Robinson D, Lam G, et al. Initial experience with a dual-balloon catheter for the management of postpartum hemorrhage. Am J Obstet Gynecol. 2014;210:e1361\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBarinov SV, Medyannikova IV, Borisova AV, Tyrskaya YI, Savelieva IV, Shamina IV, et al. The usefulness of Zhukovsky Double Balloon in obstetric hemorrhage. J Matern Fetal Med. 2019;1:10\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBarik A, Singh V, Choudhary A, Yadav P. Central placenta previa with coexisting central cervical fibroid in pregnancy: an obstetrician\u0026rsquo;s nightmare. Cureus. 2021;13:e15910.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBrown H, Okeyo S, Mabeya H, Wilkinson J, Schmitt J. The Bakri tamponade balloon as an adjunct treatment for refractory postpartum hemorrhage. Int J Gynaecol Obstet. 2016;135:276\u0026ndash;80.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWright CE, Chauhan SP, Abuhamad AZ. Bakri balloon in the management of postpartum hemorrhage: a review. Am J Perinatol. 2014;31:957\u0026ndash;64.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-pregnancy-and-childbirth","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"prch","sideBox":"Learn more about [BMC Pregnancy and Childbirth](http://bmcpregnancychildbirth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/prch/default.aspx","title":"BMC Pregnancy and Childbirth","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"OB balloon, cesarean section, placenta previa, double balloon tamponade","lastPublishedDoi":"10.21203/rs.3.rs-7147446/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7147446/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003ePlacenta previa and low-lying placenta are associated with substantial peripartum hemorrhagic complications, particularly during cesarean delivery. This retrospective study compared the efficacy and safety of a newly developed OB balloon\u0026mdash;featuring a double-balloon structure designed to simultaneously compress the uterine and vaginal sides\u0026mdash;with the conventional Bakri balloon for intrauterine tamponade.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eWe retrospectively analyzed cases of placenta previa or low-lying placenta managed with either the OB or Bakri balloon during cesarean delivery. The primary outcome was balloon failure, defined as inadequate postoperative bleeding control requiring additional interventions despite balloon tamponade. Secondary outcomes included insertion time, inflation volume, postoperative blood loss, and balloon prolapse.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eA total of 47 cases were analyzed: 20 in the OB group and 27 in the Bakri group. Balloon failure occurred in 5 cases (18.5%) in the Bakri group\u0026mdash;all associated with balloon prolapse\u0026mdash;whereas no failures occurred in the OB group. Balloon prolapse was observed in 6 cases (22.2%) in the Bakri group and none in the OB group. No significant differences were found in insertion time or postoperative blood loss between the groups.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eThe OB balloon reduced the incidence of balloon prolapse while maintaining comparable hemostatic efficacy. These findings suggest that the OB balloon offers a more stable hemostatic option for cesarean deliveries complicated by abnormal placentation.\u003c/p\u003e","manuscriptTitle":"Efficacy of OB Balloon Tamponade in Cesarean Delivery for Placenta Previa and Low-Lying Placenta: A Retrospective Comparative Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-03 11:31:12","doi":"10.21203/rs.3.rs-7147446/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-01-05T11:50:26+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-23T19:01:16+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-14T14:42:13+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"171131436011439641033579561580947039056","date":"2025-12-11T19:12:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"21133591070011289569876396987286840490","date":"2025-12-07T04:25:21+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-12-07T03:59:49+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-12-03T03:41:00+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Pregnancy and Childbirth","date":"2025-12-02T13:21:00+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-pregnancy-and-childbirth","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"prch","sideBox":"Learn more about [BMC Pregnancy and Childbirth](http://bmcpregnancychildbirth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/prch/default.aspx","title":"BMC Pregnancy and Childbirth","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"719b4697-5c44-4bc3-a395-4dfde0857ddb","owner":[],"postedDate":"December 3rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-02-09T16:07:51+00:00","versionOfRecord":{"articleIdentity":"rs-7147446","link":"https://doi.org/10.1186/s12884-026-08730-0","journal":{"identity":"bmc-pregnancy-and-childbirth","isVorOnly":false,"title":"BMC Pregnancy and Childbirth"},"publishedOn":"2026-02-04 15:57:29","publishedOnDateReadable":"February 4th, 2026"},"versionCreatedAt":"2025-12-03 11:31:12","video":"","vorDoi":"10.1186/s12884-026-08730-0","vorDoiUrl":"https://doi.org/10.1186/s12884-026-08730-0","workflowStages":[]},"version":"v1","identity":"rs-7147446","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7147446","identity":"rs-7147446","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}