Assisted vaginal birth in 21st century: current practice and new innovations

Assisted vaginal birth rates are falling globally with rising cesarean delivery rates. Cesarean delivery is not without consequence, particularly when carried out in the second stage of labor. Cesarean delivery in the second stage is not entirely protective against pelvic floor morbidity and can lead to serious complications in a subsequent pregnancy. It should be acknowledged that the likelihood of morbidity for mother and baby associated with cesarean delivery increases with advancing labor and is greater than spontaneous vaginal birth, irrespective of the method of operative birth in the second stage of labor. In this article, we argue that assisted vaginal birth is a skilled and safe option that should always be considered and be available as an option for women who need assistance in the second stage of labor. Selecting the most appropriate mode of birth at full dilatation requires accurate clinical assessment, supported decision-making, and personalized care with consideration for the woman's preferences. Achieving vaginal birth with the primary instrument is more likely with forceps than with vacuum extraction (risk ratio, 0.58; 95% confidence interval, 0.39-0.88). Midcavity forceps are associated with a greater incidence of obstetric anal sphincter injury (odds ratio, 1.83; 95% confidence interval, 1.32-2.55) but no difference in neonatal Apgar score or umbilical artery pH. The risk for adverse outcomes is minimized when the procedure is conducted by a skilled accoucheur who selects the most appropriate instrument likely to achieve vaginal birth with the primary instrument. Anticipation of potential complications and dynamic decision-making are just as important as the technique for safe instrument use. Good communication with the woman and the birthing partner is vital and there are various recommendations on how to achieve this. There have been recent developments (such as OdonAssist) in device innovation, training, and strategies for implementation at a scale that can provide opportunities for both improved outcomes and reinvigoration of an essential skill that can save mothers' and babies' lives across the world.

The OdonAssist inflatable device for assisted vaginal birth-the ASSIST II study (United Kingdom)

BACKGROUND

Decreasing rates of assisted vaginal birth have been paralleled with increasing rates of cesarean deliveries over the last 40 years. The OdonAssist is a novel device for assisted vaginal birth. Iterative changes to clinical parameters, device design, and technique have been made to improve device efficacy and usability.

OBJECTIVE

This study aimed to determine if the feasibility, safety, and efficacy of the OdonAssist device were sufficient to justify conducting a future randomized controlled trial.

STUDY DESIGN

An open-label nonrandomized study of 104 participants having a clinically indicated assisted vaginal birth using the OdonAssist was undertaken at Southmead Hospital, Bristol, United Kingdom. Data were also collected from participants who consented to participate in the study but for whom trained OdonAssist operators were not available, providing a nested cohort. The primary clinical outcome was the proportion of births successfully expedited with the OdonAssist. Secondary outcomes included clinical, patient-reported, operator-reported, device and health care utilization. Neonatal outcome data were reviewed at day 28, and maternal outcomes were investigated up to day 90. Given that the number of successful OdonAssist births was ≥61 out of 104, the hypothesis of a poor rate of 50% was rejected in favor of a good rate of ≥65%.

RESULTS

Between August 2019 and June 2021, 941 (64%) of the 1471 approached, eligible participants consented to participate. Of these, 104 received the OdonAssist intervention. Birth was assisted in all cephalic vertex fetal positions, at all stations ≥1 cm below the ischial spines (with or without regional analgesia). The OdonAssist was effective in 69 of the 104 (66%) cases, consistent with the hypothesis of a good efficacy rate. There were no serious device-related maternal or neonatal adverse reactions, and there were no serious adverse device effects. Only 4% of neonatal soft tissue bruising in the successful OdonAssist group was considered device-related, as opposed to 20% and 23% in the unsuccessful OdonAssist group and the nested cohort, respectively. Participants reported high birth perception scores. All practitioners found the device use to be straightforward.

CONCLUSION

Recruitment to an interventional study of a new device for assisted vaginal birth is feasible; 64% of eligible participants were willing to participate. The success rate of the OdonAssist was comparable to that of the Kiwi OmniCup when introduced in the same unit in 2002, meeting the threshold for a randomized controlled trial to compare the OdonAssist with current standard practice. There were no disadvantages of study participation in terms of maternal and neonatal outcomes. There were potential advantages of using the OdonAssist, particularly reduced neonatal soft tissue injury. The same application technique is used for all fetal positions, with all operators deeming the device straightforward to use. This study provides important data to inform future study design.

The use of bubble charts in analyzing second stage cesarean delivery rates

BACKGROUND

The incidence of second stage cesarean delivery has been rising globally because of the failure or the anticipated difficulty of performing instrumental delivery. Yet, the best way to interpret the figure and its optimal rate remain to be determined. This is because it is strongly influenced by the practice of other 2 modes of birth, namely cesarean delivery performed before reaching the second stage and assisted vaginal birth during the second stage. In this regard, a bubble chart that can display 3-dimensional data through its x-axis, y-axis, and the size of each plot (presented as a bubble) may be a suitable method to evaluate the relationship between the rates of these 3 modes of births.

OBJECTIVE

This study aimed to conduct an epidemiologic study on the incidence of second stage cesarean deliveries rates among >300,000 singleton term births in 10 years from 8 obstetrical units and to compare their second stage cesarean delivery rates in relation to their pre-second stage cesarean delivery rates and assisted vaginal birth rates using a bubble chart.

STUDY DESIGN

The territory-wide birth data collected between 2009 and 2018 from all 8 public obstetrical units (labelled as A to H) were reviewed. The inclusion criteria were all singleton pregnancies with cephalic presentation that were delivered at term (≥37 weeks' gestation). Pre-second stage cesarean delivery rate was defined as all elective cesarean deliveries and those emergency cesarean deliveries that occurred before full cervical dilatation was achieved as a proportion of the total number of births. The second stage cesarean delivery rate and assisted vaginal birth rate were calculated according to the respective mode of delivery as a proportion of the number of cases that reached full cervical dilatation. The rates of these 3 modes of births were compared among the parity groups and among the 8 units. Using a bubble chart, each unit's second stage cesarean delivery rate (y-axis) was plotted against its pre-second stage cesarean delivery rate (x-axis) as a bubble. Each unit's second stage cesarean delivery to assisted vaginal birth ratio was represented by the size of the bubble.

RESULTS

During the study period, a total of 353,434 singleton cephalic presenting term pregnancies were delivered in the 8 units, and 180,496 (51.1%) were from nulliparous mothers. When compared with the multiparous group, the nulliparous group had a significantly lower pre-second stage cesarean delivery rate (18.58% vs 21.26%; P<.001) but a higher second stage cesarean delivery rate (0.79% vs 0.22%; P<.001) and a higher assisted vaginal birth rate (17.61% vs 3.58%; P<.001). Using the bubble of their averages as a reference point in the bubble chart, the 8 units' bubbles were clustered into 5 regions indicating their differences in practice: unit B and unit H were close to the average in the center. Unit A and unit F were at the upper right corner with a higher pre-second stage cesarean delivery rate and second stage cesarean delivery rate. Unit D and unit E were at the opposite end. Unit C was at the upper left corner with a low pre-second stage cesarean delivery rate but a high second stage cesarean delivery rate, whereas unit G was at the opposite end. Unit C and unit G were also in the extremes in terms of pre-second stage cesarean delivery to assisted vaginal birth ratio (0.09 and 0.01, respectively). Although some units seemed to have very similar second stage cesarean delivery rates, their obstetrical practices were differentiated by the bubble chart.

CONCLUSION

The second stage cesarean delivery rate must be evaluated in the context of the rates of pre-second stage cesarean delivery and assisted vaginal birth. A bubble chart is a useful method for analyzing the relationship among these 3 variables to differentiate the obstetrical practice between different units.

Association of the Kiwi OmniCup system with maternal and neonatal morbidity: A retrospective cohort study

OBJECTIVE

To discuss the effect of the Kiwi OmniCup system on reducing adverse maternal and neonatal outcomes and provide a reference for assisted vaginal delivery methods.

METHODS

Women who gave birth to singleton term neonates in a cephalic presentation and underwent assisted vaginal delivery from 2017 to 2021 were eligible for inclusion in the study; they were divided into a Kiwi OmniCup system group and a forceps group. Binary logistic regression analysis was used to observe and compare maternal and neonatal outcomes. The primary outcomes were severe maternal and neonatal morbidity. Severe maternal morbidity was defined as the occurrence of at least one of the following outcomes: third- or fourth-degree perineal lacerations, refractory postpartum hemorrhage, thrombotic events, amniotic fluid embolism, admission to the intensive care unit, and maternal death. Severe neonatal morbidity was defined as the occurrence of at least one of the following outcomes: neonatal asphyxia requiring resuscitation or intubation, neonatal head and face injuries, neonatal fracture, and admission to the neonatal intensive care unit for longer than 24 h.

RESULTS

The rate of severe neonatal morbidity in the forceps group was significantly higher than that in the Kiwi OmniCup system group, the differences between the two groups were significant (27.2% vs. 42.3%, P < 0.001), and there was no significant difference in the rate of severe maternal morbidity between the two groups (30% vs. 30%, P > 0.05). Binary logistic regression analysis showed that Kiwi OmniCup system-assisted delivery reduced severe neonatal morbidity (adjusted odds ratio 0.49; 95% confidence interval 0.33-0.73) and did not increase severe maternal morbidity compared with forceps-assisted delivery.

CONCLUSION

The Kiwi OmniCup system, which can reduce the incidence of severe neonatal morbidity without increasing the incidence of serious adverse maternal outcomes, is worthy of clinical promotion.

Outcomes of the novel Odon Device in indicated operative vaginal birth

BACKGROUND

No new method of assisting vaginal birth has been introduced into clinical practice since the development of the vacuum extractor in the 1950s. The Odon Device is a new device that employs a circumferential air cuff over the fetal head to assist birth. In this study, the Odon Device has been used to assist vaginal birth for standard clinical indications.

OBJECTIVE

This study aimed to investigate the clinical impact, safety, and acceptability of the Odon Device to women, their babies, and clinicians and to assess the feasibility of recruiting women to an interventional intrapartum research study.

STUDY DESIGN

This is a nonrandomized, single-arm interventional feasibility study of the Odon Device for operative vaginal birth undertaken in a single maternity unit: Southmead Hospital, Bristol, United Kingdom. The Odon Device was used to assist birth in 40 women who required the birth to be assisted for suspected fetal compromise and/or prolonged second stage of labor. The primary clinical outcome was the proportion of births successfully assisted with the Odon Device, and the primary feasibility outcome was the proportion of eligible women who were approached and who agreed to participate. Neonatal outcome data were reviewed at day 28, and maternal outcomes were investigated up to day 90.

RESULTS

Between October 2018 and January 2019, 298 of 384 approached, eligible women (77.6%) consented to participate. Of these women, 40 received the intervention-the use of the Odon Device. Birth was assisted in all cephalic (occiput anterior, occiput transverse, and occiput posterior) fetal positions, at all stations at or below the ischial spine and with or without regional analgesia. The Odon Device was effective in 19 of 40 cases (48%). Of the 40 births, 21 (52.5%) required additional assistance: 18 of 40 births (45%) were completed using nonrotational forceps, 1 of 40 births (3%) required rotational forceps, and 2 of 40 births (5%) required an emergency cesarean delivery. There was no serious maternal or neonatal adverse event related to the use of the device, and there was no serious adverse device effect. There were 4 devices (10%) that were ineffective because of a manufacturing fault. Furthermore, 39 of 40 women (98%) reported a high birth perception score. All practitioners were able to use the device as intended, although some steps in using the device were reported to be easier to perform (setup and deflation of air chamber) than others (application of the device and withdrawal of the applicator).

CONCLUSION

Recruitment to an interventional study of a new device for operative vaginal birth was feasible; 78% of eligible women were willing to participate, often expressing an aspiration for an alternative to forceps and vacuum. The success rate of the Odon Device was lower than reported success rates of vacuum and forceps; however, in this study, the device had been used to assist birth for standard clinical indications. There was no significant maternal or neonatal safety concern associated with the use of the device, although the number of births studied was small. Further feasibility study to establish iterative changes to the device, technique, and clinical indications is necessary.

Birth tears after spontaneous and vacuum-assisted births with different vacuum cup systems - a retrospective cohort study

Objectives Birth tears are a common complication of vaginal childbirth. We aimed to evaluate the outcomes of birth tears first by comparing the mode of vaginal birth (VB) and then comparing different vacuum cups in instrumental VBs in order to better advise childbearing women and obstetrical professionals. Methods In a retrospective cohort study, we analyzed nulliparous and multiparous women with a singleton pregnancy in vertex presentation at ≥37 + 0 gestational weeks who gave birth vaginally at our tertiary care center between 06/2012 and 12/2016. We compared the distribution of tear types in spontaneous births (SBs) vs. vacuum-assisted VBs. We then compared the tear distribution in the vacuum group when using the Kiwi Omnicup or Bird's anterior metal cup. Outcome parameters were the incidence and distribution of the different tear types dependent on the mode of delivery and type of vacuum cup. Results A total of 4549 SBs and 907 VBs were analyzed. Birth tear distribution differed significantly between the birth modes. In 15.2% of women with an SB an episiotomy was performed vs. 58.5% in women with a VB. Any kind of perineal tear was seen in 45.7% after SB and in 32.7% after VB. High-grade obstetric anal sphincter injuries (OASIS) appeared in 1.1% after SB and in 3.1% after VB. No significant changes in tear distribution were found between the two different VB modes. Conclusions There were more episiotomies, vaginal tears and OASIS after VB than after SB. In contrast, there were more low-grade perineal and labial tears after SB. No significant differences were found between different vacuum cup systems, just a slight trend toward different tear patterns.

Operative vaginal delivery: a review of four national guidelines

There is a broad range in the rates of operative vaginal deliveries (OVD) worldwide, which reflects the variety of local practice patterns, the number of trained clinicians and the lack of international evidence-based guidelines. The aim of this study was to review and compare the recommendations from published guidelines on OVD. Thus, a descriptive review of guidelines from the Royal College of Obstetricians and Gynaecologists (RCOG), the Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG), the Society of Obstetricians and Gynaecologists of Canada (SOGC) and the American College of Obstetricians and Gynecologists (ACOG) on instrumental vaginal birth was conducted. All the guidelines point out that the use of any instrument should be based on the clinical circumstances and the experience of the operator. The indications, the contraindications, the prerequisites and the classification for OVD are overall very similar in the reviewed guidelines. Further, they all agree that episiotomy should not be performed routinely. The RCOG, the RANZCOG and the SOGC describe some interventions which may promote spontaneous vaginal birth and therefore reduce the need for OVD. They also highlight the importance of adequate postnatal care and counseling. There is no consensus on the actual technique that should be used, including the type of forceps or vacuum cup, the force and duration of traction or the number of detachments allowed. Hence, there is need for international practice protocols, so as to encourage the clinicians to use OVD when indicated, minimize the complications and reduce rates of cesarean delivery.

Exploring standardisation, monitoring and training of medical devices in assisted vaginal birth studies: protocol for a systematic review

INTRODUCTION

Assisted vaginal birth (AVB) can markedly improve maternal and neonatal outcomes arising from complications in the second stage of labour. Historically, both forceps and ventouse devices have been used to assist birth; however, they are not without risk and are associated with complications, such as cephalohaematoma, retinal haemorrhage and perineal trauma. As new devices are developed to overcome the limitations of existing techniques, it is necessary to establish their efficacy and effectiveness within randomised controlled trials (RCTs). A major challenge of evaluating complex interventions (ie, invasive procedures/devices used to assist vaginal birth) is ensuring they are delivered as intended. It can be difficult to standardise intervention delivery and monitor fidelity, and account for the varying expertise of clinicians (accoucher expertise). This paper describes the protocol for a systematic review aiming to investigate the reporting of device standardisation, monitoring and training in trials evaluating complex interventions, using AVB as a case study.

METHODS AND ANALYSIS

Relevant keywords and subject headings will be used to conduct a comprehensive search of MEDLINE, Embase, Cochrane Central Register of Controlled Trials, Cumulative Index of Nursing and Allied Health Literature and ClinicalTrials.gov, for RCTs and pilot/feasibility studies evaluating AVB. Abstracts will be screened and full-text articles of eligible studies reviewed for inclusion. Information relating to the following categories will be extracted: standardisation of device use (ie, descriptions of operative steps, including mandatory/flexible parameters), monitoring of intervention delivery (ie, intervention fidelity, confirming that an intervention is delivered as intended) and accoucher expertise (ie, entry criteria for participation, training programmes and previous experience with the device). Risk of bias of included studies will be assessed.

ETHICS AND DISSEMINATION

Ethical approval is not required because primary data will not be collected. Findings will be disseminated by publishing in a peer-reviewed journal and presentations at relevant conferences.