Evaluation of the synthetic osmotic dilator (Dilapan-S®) for induction of labour through a multicentre retrospective registry of real-world data in the United Kingdom.

Evaluation of the synthetic osmotic dilator (Dilapan-S®) for induction of labour through a multicentre retrospective registry of real-world data in the United Kingdom. | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 19 January 2026 V1 Latest version Share on Evaluation of the synthetic osmotic dilator (Dilapan-S®) for induction of labour through a multicentre retrospective registry of real-world data in the United Kingdom. Authors : Chineze Otigbah , Summia Samir Zaher , Deniesha Campbell , Olaleye Sanu , W John Watkins , Jan Waclav , and Thomas Everett 0009-0001-4576-0842 [email protected] Authors Info & Affiliations https://doi.org/10.22541/au.176883677.72347754/v1 196 views 93 downloads Contents Abstract Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Introduction : In 2015, Dilapan-S was approved by the FDA for cervical ripening in pregnancy. This synthetic hygroscopic agent for labour induction has increased the options for initiating labour. This real-world evaluation aims to determine if Dilapan-S use in routine practice within UK demonstrates outcomes achieved by studies in other health systems. Materials and methods : Five large maternity units were recruited to the study due to their routine use of Dilapan-S. Primary outcomes were duration in situ and insertion-delivery interval. Secondary outcomes were the number of dilators used, and Bishop score change. Analgesia use during and after insertion and post-induction complications were also recorded, as was mode of delivery. Results: 1,509 women were observed retrospectively. During insertion, 94.2% did not experience any complications. 55% women were suitable for ARM after one round of Dilapan-S. Mean insertion-delivery interval was 50.4hrs. Mean Bishop score increase was +2.1. The mean dilators used was five. Oxytocin was required in 59% of women; vaginal delivery rate was 59.5%. 83% of the women had no complications. 3.5% of babies were admitted to the neonatal unit; 90.2% and 97% had Apgars of 8-10 at 1 and 5 minutes, respectively. Conclusion: Dilapan-S is an effective method for induction of labour in routine clinical practice. As with other observational and randomised studies, its use is associated with low complication rates. This Real-World Evidence project assessing retrospective cohorts showed that time from insertion- delivery is more than that observed previously, largely due to delay in waiting for artificial rupture of membranes. Title: Evaluation of the synthetic osmotic dilator (Dilapan-S®) for induction of labour through a multicentre retrospective registry of real-world data in the United Kingdom. Authors and Affiliations: Chineze M Otigbah MRCOG 1 , Summia Samir Zaher 2,3 , Deniesha Campbell 4,5 , Olaleye Sanu 4 , W.John Watkins PhD 6 , Jan Waclav MD 7 , Thomas R Everett MRCOG MD 8 , 1. Dept of Obstetrics and Gynaecology, Queens Hospital Romford Barking Havering and Redbridge NHS Trust, UK 2. Danat Al Emarat Hospital for Women and Children, M42, Abu Dhabi, UAE 3. Cardiff University, UHW Main Building, Heath Park, Cardiff, CF14 4XN 4. Dept of Obstetrics and Gynaecology, West Hertfordshire Teaching Hospitals NHS Trust, UK 5. Dept of Obstetrics and Gynaecology, Royal Free London NHS Foundation, London UK 6. College of Biomedical & Life Sciences, Cardiff University, Cardiff, UK, CF14 4XN 7. Medicem Technology s.r.o., Kamenne Zehrovice, Czech Republic 8. Department of Fetal-Maternal Medicine, Leeds Teaching Hospitals NHS Trust, Leeds, UK Corresponding author: Dr Thomas Everett, Department of Fetal-Maternal Medicine, Leeds Teaching Hospitals NHS Trust, Leeds, LS1 3EX, UK,Tel: 0113 392 6829Email: [email protected] Running Title: Real World Evaluation of Labour Induction with Dilapan in UK Abstract Introduction : In 2015, Dilapan-S was approved by the FDA for cervical ripening in pregnancy. This synthetic hygroscopic agent for labour induction has increased the options for initiating labour. This real-world evaluation aims to determine if Dilapan-S use in routine practice within UK demonstrates outcomes achieved by studies in other health systems. Materials and methods : Five large maternity units were recruited to the study due to their routine use of Dilapan-S. Primary outcomes were duration in situ and insertion-delivery interval. Secondary outcomes were the number of dilators used, and Bishop score change. Analgesia use during and after insertion and post-induction complications were also recorded, as was mode of delivery. Results: 1,509 women were observed retrospectively. During insertion, 94.2% did not experience any complications. 55% women were suitable for ARM after one round of Dilapan-S. Mean insertion-delivery interval was 50.4hrs. Mean Bishop score increase was +2.1. The mean dilators used was five. Oxytocin was required in 59% of women; vaginal delivery rate was 59.5%. 83% of the women had no complications. 3.5% of babies were admitted to the neonatal unit; 90.2% and 97% had Apgars of 8-10 at 1 and 5 minutes, respectively. Conclusion: Dilapan-S is an effective method for induction of labour in routine clinical practice. As with other observational and randomised studies, its use is associated with low complication rates. This Real-World Evidence project assessing retrospective cohorts showed that time from insertion- delivery is more than that observed previously, largely due to delay in waiting for artificial rupture of membranes. Introduction Induction of labour (IOL) is the process of artificially stimulating the uterus to start labour (1). The recommended labour induction methods are membrane sweeping, pharmacological, and mechanical (2). The incidence of induction has increased over the years, particularly in high-income countries where facilities for intrapartum monitoring are immediately available, and there are provisions for safe caesarean section (3). The current incidence of IOL in the UK has risen from 22% to 33% over the last 10 years. This is due to the implementation of various recommendations to reduce the incidence of stillbirths by 50% by 2030 in the UK. This is likely to be mirrored in other high-income countries (4). In 2013, the incidence of IOL was 4.4% in Africa and 12% in Asia, respectively (5). Elective inductions in Latin America represented 4.9% of low-risk pregnancies in 2011 (6). Mechanical methods were the primary agents used to induce labour in various forms until pharmacological methods were introduced in the 1960s. Laminaria tents, made from processed seaweed and the precursor to today’s artificial hygroscopic inducing agents, were primarily used for cervical ripening for termination of pregnancy but eventually discontinued due to their association with maternal infections and fragmentation (7). There has been a recent resurgence in mechanical methods, including single and double balloons and synthetic hygroscopic agents like Dilapan-S. Dilapan-S is a synthetic osmotic dilator made from a well-tolerated, patented hydrogel, Aquacryl (13,16). Typically, 4-5 dilators are inserted into the cervix, slowly absorbing moisture and swelling to apply gentle mechanical pressure, resulting in a dilated, soft, and pliable cervix after removal. The cervical ripening process with Dilapan-S varies, typically lasting from a few hours to a day, and is recognised for its high success rate and minimal complications (13, 16). An ideal inducing agent should be able to implement cervical change, such that the initiation of labour begins with minimal delay, with a good safety profile (i.e., minimal impact on fetal or maternal well-being), reduced need for pain relief or continuous monitoring, and the desired outcome of vaginal delivery with minimal complications. This study aims to document the efficacy and safety of Dilapan-S under routine clinical conditions (Real World Evidence – RWE) compared to the strict research-based outcomes of the published randomised controlled studies or prospective observational studies and see if it achieves similar outcomes and the desired aims of an ideal inducing agent. Methods: Five large maternity units in the United Kingdom were identified to participate in the study. The maternity units were large and delivered between 5000 and 9000 babies annually. They already had established protocols for using Dilapan­S as one of their IOL options. Dilapan-S was the primary induction agent for some units; for others, it was used only in situations where it was felt pharmacological methods were contraindicated or less safe, such as for vaginal birth after caesarean section or in outpatient induction. These units also had protocols that permitted adjuvant agents if the cervix remained unfavourable or to prevent interrupting the induction due to delays unrelated to the actual induction process. The maternity units varied in who administered the Dilapan-S; most were midwifery-led, and in others, a combination of midwife and doctor administrations with a set insertion protocol, training program, standard operating procedure, and competency assessments before independent practice. The insertion of Dilapan-S was performed as documented by the manufacturers and described by Gupta et al. (8). Removal of the agents and their disposal was also part of the training. Data Collection: The data collection period extended from September 2020 to May 2023. The inclusion criteria retrospectively targeted medical records of women who delivered after undergoing IOL with Dilapan-S. The women included in the project were 18 years or older and had a gestation period of greater than or equal to 37 weeks. The data was obtained from University Hospital of Wales (acting as the lead and coordinating site), Queen’s Hospital Romford, Watford General Hospital, Leeds Teaching Hospitals NHS Trust, and Kingston Hospital. Cardiff University provided the statistical support necessary to analyse the data. The requirement for ethics/CAG (Confidentiality Advisory Group) had been assessed using the NHS HRA Decision Tool as not requiring formal ethics approval, as the data was completely anonymised and this formed a service evaluation for each participating unit. After receiving approval from the local Trust directorates, each participating institution collected anonymised data using a standardised case report form (CRF). This data was centralised on MedSciNet, a secure platform compliant with FDA, NIH, and HL7 standards, ensuring data integrity and adherence to medical research best practices. Statistical methods: Basic descriptive analysis was conducted with counts (and percentages) and means (and standard deviations) calculated as appropriate. Some variables were banded for clarity and interpretability. Statistical tests including chi-squared test for proportions and t-tests or the non-parametric equivalent for comparing the distribution of continuous variable were conducted and significance levels (p values) reported. SPSS version 29.0.2.0 was used for all statistical analysis. Results: The study cohort comprised 1,509 records from five hospitals in the UK. As this was an RWE project, it was anticipated there would be some data missing; this is reflected in the tables and figures with analysis based on the available data in each group. The average age of participants was 31 (± 5.7) years, and the average body mass index (BMI) was 28.1 (± 6.3). 58% of the study participants were nulliparous while 42% were multiparous; 9.8% recorded a history of previous caesarean section, including 3 (0.2%) with two caesarean births in medical history. Additional baseline characteristics of the study population are detailed in Table 1. The most common primary indications for IOL included diabetes during pregnancy (19.4%), small for gestational age (16.1%), post-term pregnancy (at gestation determined as per local guideline) (14.6%), and reduced fetal movements (13.3%). The criteria also included indications that could not be classified as an independent large group, so they were described as ‘Other’. The number of women requesting induction of labour for non-obstetric reasons was 2.1%. Interestingly, despite Dilapan­S not being contraindicated for use in women with prolonged rupture of membranes, only 2 women (0.1%) were offered IOL with this method of induction. The median number of inserted dilators used was 5, with no significant difference between nulliparas and multiparas. More than 94% of the women received 4 or 5 dilators, which is number typically achieved also in RCTs (9,10,11,12). Those women receiving between 1-3 dilators was less than 6%; this sample size was too small to determine the number of dilators needed for adequate cervical change however there were lower numbers of vaginal deliveries in this sub-group (Table 2). The vast majority of the women (94.2%) encountered no complications during the placement of Dilapan-S (Table 3). The most common complication while Dilapan-S in situ was minor vaginal bleeding in 3.7% of cases. Most women (90.2%) tolerated the dilators in situ without analgesia, thus contributing to maternal satisfaction. Difficulty in inserting the dilators only occurred in 0.6% of the women in the study. Only a single participant had rupture of membranes, contractions or rod expulsion during the insertion process. The average pre-insertion Bishop score for both multiparous and nulliparous women was 2.7, and the average Bishop score after extraction was 4.8, which accounts for an average gain of 2.1 score points. This was based on median insertion time of dilators of 14.8 hours. Only 4.4% of the women undergoing inpatient IOL experienced an earlier removal of the Dilapan-S dilators, primarily due to spontaneous rupture of membranes during the ripening process (28/1509 = 1.9%). Outpatient cervical ripening was used in 11.9% of cases (179/1509), and of these only 1.7% (3/179) of women returned earlier than anticipated. In 44.3% of cases (667/1509), additional ripening after the first round of Dilapan­S was needed. This was either by a second round of dilators or prostaglandins. This was significantly more common in the nulliparous (51.3% vs 34.7%, p-value <0.001), maternal age over 25 years (p-value 0.003), obese women (p-value 0.009), gestational age of ≥42 weeks (p-value 0.013), and black ethnic background (p-value 0.032). The average insertion-to-ARM time with SD was 39.8 hours (±23.9 hours), with a mean removal-to-ARM time of 25.6hours (±23.3 hours). The average insertion-to-delivery time was 52.0 hours (±25.2 hours)(Figure 1). The total vaginal delivery rate was 59.5% (Table 4). Multiparous women had a significantly higher chance of vaginal birth than primiparous (70.7% vs 51.3%, p-value <0.001). Obese women had significantly more caesarean births than women with lower BMI (Table 4). Based on ethnicity, only black women were more likely to have emergency caesarean sections than vaginal deliveries (57.9% and 42.1% respectively, p-value <0.001). Most of women (83.8%) experienced no intrapartum or early postpartum infectious complications (Table 5). The most common infection was chorioamnionitis (5%), followed by suspected sepsis (or sepsis-like symptoms, eg. pyrexia or tachycardia) (4.1%). Due to the nature of this study, the administration of antibiotics was used as the surrogate for the diagnosis of ‘sepsis’ which likely artificially increased the numbers diagnosed with ‘sepsis’. The use of the term ’sepsis’ most likely reflects reports of chorioamnionitis and pyrexia in labour, rather than true sepsis. Only 3 women (0.2%) experienced sepsis. Postpartum haemorrhage occurred in 7.6 % of women (114/1509). With regard to neonatal outcomes, 3.5% of the babies born to mothers induced with Dilapan-S dilators needed NICU care, for reasons usually associated with term admissions to NICU. The Apgar score of 0-7 at 1 minute and 5 minutes was encountered in 9.6% and 2.2% of the babies, respectively, with no significant influence by the mode of delivery. In the subgroup that underwent IOL as outpatients (Table 4), there was no difference in the outcome of these women compared to those who were induced as inpatients. Discussion: Numerous clinical trials and RCTs indicate Dilapan-S is a safe, efficient, and cost-effective method for cervical ripening comparable to other methods (9, 10, 11, 12). The Dilapan-S registry represents a valuable initiative aimed at enhancing our understanding of Dilapan-S’ effectiveness in routine labour induction. By focusing on real-world patient experiences rather than solely relying on traditional randomized controlled trials, this study seeks to provide insights that are more broadly applicable to diverse populations and a better reflection of routine clinical application. In this Dilapan-S registry study, the major findings included vaginal delivery rate of 59.5%. Women who were obese, nulliparous, and lack had a higher likelihood of caesarean section. The higher rate of caesarean section in with nulliparity and increasing BMI has been previously repeatedly observed. The reason for the higher rate of caesarean section in black women is less clear, however this pattern has been observed more widely in analysis of recent UK Health Episode Statistics (HES) data (17) and the complex reasons underlying this are beyond the scope of this study, but are unlikely to be related to any particular induction modality. Multiparous women had a significantly higher chance of vaginal birth (70.7%). The data also demonstrated that the Dilapan-S was generally well-tolerated, and the safety profile was consistent with that found in the recent RCTs and individual patient data meta-analysis (13). The efficacy of Dilapan-S, as indicated by the vaginal delivery rate in this study, though confirmed, was found to be lower than that reported in RCTs (9,10,11,12). This disparity can potentially be attributed to Hawthorne effect in the index studies and to differences in clinical practices across the sites involved in the study. The nature of the study made the effect of site-specific practice on the outcomes difficult to assess, with some units having a lower threshold for abandoning induction. This was particularly relevant as during the time of the collection of this data, changes were made to the way induction of labour and its management was implemented. This included an increase in the number of inductions, due to changes in the provision of care in the United Kingdom, such as Saving Babies Lives version 2 in 2019 (14) and Ockenden report in 2022 (15). These were directives and reports produced to improve neonatal and maternal outcomes. As a result, the number of interventions increased, without a change in capacity within the hospitals and also increasing reporting women changing their minds about mode of delivery and requesting caesarean section during the induction process. The delays in transfer to labour ward, therefore, made the induction to delivery data artificially lengthened, which may explain why the average length of time from commencement of induction to delivery was nearer 50 hours compared to 24­25 hours in the RCTs (9,11). On review of the data, the mean time between removal of the dilators and ARM was 25.6 hours. This might explain the lower vaginal delivery rate (59.5%) achieved in this RWE project, compared to vaginal delivery rate of between 60.3-80% in the RCTs (13,16). Prolonged intervals before ARM not only prolong the overall duration of the induction of labour process but is also responsible for the inductions being abandoned due to dissatisfaction of the delay, resulting in the increased number of Caesarean sections performed, rather than due to inducing agent failure. Another reason might be the reluctance to the use of other pharmacological agents once cervical ripening has been achieved with Dilapan-S. We noticed this trend at various locations; however, additional data and a more detailed analysis are necessary to draw definitive conclusions. The safety profile of Dilapan-S proved to be favourable, with no significant difference compared to the safety profile reported in RCTs. Higher than expected occurrence of suspected chorioamnionitis in this RWE project may be attributed to absence of study defined criteria for the use of antibiotics, which was a surrogate marker of infection. This is different from RCTs where there is a fixed definition of an infection, leading to a prescription of antibiotics. This assumption is supported by low need for NICU admission and overall good outcomes in neonates. Its safety, along with tolerability, evidenced by a low requirement for analgesia on insertion and in situ, contributes to its suitability for outpatient cervical ripening, suggesting high levels of maternal comfort and satisfaction. The versatility of Dilapan-S was evident because of its efficacy and safety profile in all clinical contexts, including women who have had previous caesarean sections or comorbidities and cases with vulnerable fetuses. This showcases its effectiveness across a wide range of obstetric scenarios. This predictability not only expands the option of Dilapan-S for use in outpatient ripening but also allows more reliable scheduling and logistics of overloaded labour wards. Conclusion: The Dilapan-S registry, as a RWE project, provides valuable insights into the use of Dilapan-S in routine clinical practice. It complements the evidence from RCTs, offering a more generalizable understanding of Dilapan-S effectiveness and safety in labour induction. Our data demonstrates that Dilapan-S is safe and well tolerated for the induction of labour; it has minimal side effects and can be effective for use as a cervical ripening agent in a wide variety of settings and indications, including out-patient and for high-risk pregnancies with a previously scarred uterus or pregnancies with a vulnerable fetus. We support Dilapan-S to be used as the first-line method for IOL in maternity units. Future research is necessary to continue to leverage both RCTs and RWE to provide a comprehensive understanding of the induction of labour in obstetric care. The dataset of this e-registry of more than 1500 successfully induced patients allows for more detailed analyses across different subpopulations in future publications on this inducing agent. Acknowledgement: Dr Gabrielle Bambridge and with research and digital midwives at each unit for their support in data collection. Disclosure of Interests: JW is an Employee of Medicem Technology s.r.o. (manufacturer of Dilapan-S). Contribution of Authorship CO, SSZ, TRE wrote the manuscript. JW designed the study and contributed to manuscript preparation and revision. WJW performed statistical analysis and contributed to manuscript preparation and revision. All other co-authors were involved in data collection and manuscript review and revision. Details of Ethics Approval Assessed using the NHS HRA Decision Tool as not requiring formal ethics approval. Local R&D approval was sought and granted in each participating unit. Funding: No funding received. (Medichem employs JW, but otherwise did not fund or have involvement in data collection, analysis or manuscript preparation.) Supplementary Material File (uk reg article tables - final and clean - 19 dec 2025.docx) Download 44.99 KB Information & Authors Information Version history V1 Version 1 19 January 2026 Copyright This work is licensed under a Non Exclusive No Reuse License. Keywords general obstetrics labour: induction Authors Affiliations Chineze Otigbah Barking Havering and Redbridge University Hospitals NHS Trust View all articles by this author Summia Samir Zaher Danat Al Emarat Hospital View all articles by this author Deniesha Campbell West Hertfordshire Teaching Hospitals NHS Trust View all articles by this author Olaleye Sanu West Hertfordshire Teaching Hospitals NHS Trust View all articles by this author W John Watkins Cardiff University School of Healthcare Sciences View all articles by this author Jan Waclav MEDICEM Institute sro View all articles by this author Thomas Everett 0009-0001-4576-0842 [email protected] Leeds Teaching Hospitals NHS Trust View all articles by this author Metrics & Citations Metrics Article Usage 196 views 93 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Chineze Otigbah, Summia Samir Zaher, Deniesha Campbell, et al. Evaluation of the synthetic osmotic dilator (Dilapan-S®) for induction of labour through a multicentre retrospective registry of real-world data in the United Kingdom.. Authorea . 19 January 2026. DOI: https://doi.org/10.22541/au.176883677.72347754/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu . 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