A cohort study of maternal and neonatal morbidity in relation to use of sequential instruments at operative vaginal delivery

Intrapartum Ultrasound Guidance to Make Safer Any Obstetric Intervention: Fetal Head Rotation, Assisted Vaginal Birth, Breech Delivery of the Second Twin

Intrapartum ultrasound (US) is more reliable than clinical assessment in determining parameters of crucial importance to optimize the management of labor including the position and station of the presenting part. Evidence from the literature supports the role of intrapartum US in predicting the outcome of labor in women diagnosed with slow progress during the first and second stage of labor, and randomized data have demonstrated that transabdominal US is far more accurate than digital examination in assessing fetal position before performing an instrumental delivery. Intrapartum US has also been shown to outperform the clinical skills in predicting the outcome and improving the technique of instrumental vaginal delivery. On this basis, some guidelines recommend intrapartum US to ascertain occiput position before performing an instrumental delivery. Manual rotation of occiput posterior position (MROP) and assisted breech delivery of the second twin are other obstetric interventions that can be performed during the second stage of labor with the support of intrapartum US. In this review article we summarize the existing evidence on the role of intrapartum US in assisting different types of obstetric intervention with the aim to improve their safety.

Incidence of obstetric anal sphincter injuries according to the type of forceps used in the Mexican population

OBJECTIVE

This study describes the frequency of obstetric anal sphincter injuries (OASIS) in patients after instrumental delivery according to the type of forceps used.

METHODS

A retrospective comparative cohort study was conducted on patients who underwent instrumental delivery from January 2017 to April 2022. The primary outcome was the presence of OASIS following delivery. Patients were categorized into Cohort A if only rotation forceps were used, Cohort B for only traction forceps, and Cohort C if both types were used sequentially. Statistical analysis was performed with SPSS (IBM, New York, NY) with χ2, Fisher's exact, and analysis of variance testing. A P-value <0.05 was considered significant.

RESULTS

OASIS occurred in 45 of 328 instrumental deliveries. OASIS after rotation forceps occurred in 12.9% (n = 8) of cases, after traction forceps in 13.2% (n = 34), and after sequential use of rotation and traction forceps in 37.5% (n = 3) of cases (p = 0.141). An odds ratio (OR) of 0.91 (95% confidence interval [CI] 0.40-2.08) for OASIS was obtained with the use of rotation forceps, 0.81 (95% CI 0.38-1.70) for traction forceps, and 3.97 (95% CI 0.91-17.2) for the sequential use of rotation and traction forceps.

CONCLUSION

There were no significant differences in the presence of OASIS comparing traction and rotation forceps. A non-significant trend of higher OASIS following the sequential use of traction and rotation forceps was observed.

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.

Head-to-perineum distance measured transperineally as a predictor of failed midcavity vacuum-assisted delivery

BACKGROUND

During the second stage of labor, in case of a need for a fetal extraction at midcavity, the choice of attempting the procedure between operative vaginal delivery and cesarean delivery is difficult. Moreover, guidelines on this subject are not clear.

OBJECTIVE

This study aimed to identify antenatal and intrapartum parameters associated with a failed midcavity vacuum-assisted delivery and its association with maternal and neonatal adverse outcomes.

STUDY DESIGN

This was a single-center, retrospective, cohort study conducted at a tertiary maternity hospital in France from January 2010 to December 2020. Women with singleton pregnancies under epidural analgesia with nonanomalous cephalic presenting fetuses and gestational ages at ≥37 weeks of gestation, who were submitted to midcavity vacuum-assisted delivery, were included. Following the American College of Obstetricians and Gynecologists definition, midcavity was defined as the presenting part of the fetus (ie, the fetal head) found at stations 0 and +1. For research purposes, all patients were submitted to transperineal ultrasound to evaluate the head-to-perineum distance, however, this measurement did not affect the decision to perform a midcavity vacuum-assisted delivery. The primary outcome of the study was failed midcavity vacuum-assisted delivery leading to cesarean delivery or the use of a different instrument to achieve vaginal delivery.

RESULTS

Overall, 951 cases of midcavity vacuum-assisted delivery were included in this study. Failed midcavity vacuum-assisted delivery occurred in 242 patients (25.4%). Factors independently associated with failed midcavity vacuum-assisted delivery included maternal height (adjusted odds ratio, 0.96; 95% confidence interval, 0.94-0.99; P=.002), duration of the active phase of the first stage of labor (adjusted odds ratio, 1.11; 95% confidence interval, 1.05-1.17; P<.001), nonocciput anterior fetal head position (adjusted odds ratio, 1.47; 95% confidence interval, 1.06-2.04; P=.02), z score of the head-to-perineum distance (adjusted odds ratio, 1.23; 95% confidence interval, 1.05-1.43; P=.01), and birthweight of >4000 g (adjusted odds ratio, 2.04; 95% confidence interval, 1.28-3.26; P=.003). Women submitted to a failed midcavity vacuum-assisted delivery were more likely to have a major postpartum hemorrhage (7.1% vs 2.0%; P<.001), whereas neonates were more likely to have an umbilical artery pH of <7.1 (30.5% vs 19.8%; P=.001), be admitted to the neonatal intensive care unit (9.6% vs 4.7%; P=.005), and have a severe caput succedaneum (14.9% vs 0.7%; P<.001). Subgroup analysis on all patients with a fetal head station of 0 found that the head-to-perineum distance was the only independent variable associated with failed midcavity vacuum-assisted delivery (adjusted odds ratio, 1.66; 95% confidence interval, 1.29-2.12; P<.001). The area under the receiving operating characteristic curve of the head-to-perineum distance in this subgroup population was 0.67 (95% confidence interval, 0.60-0.73; P<.001), and the optimal cutoff point of the head-to-perineum distance measurement discriminating between failed and successful midcavity vacuum-assisted deliveries was 55 mm. It was associated with a 0.90 (95% confidence interval, 0.83-0.95) sensitivity, 0.19 (95% confidence interval, 0.14-0.25) specificity, 0.36 (95% confidence interval, 0.30-0.42) positive predictive value, and 0.80 (95% confidence interval, 0.66-0.90) negative predictive value.

CONCLUSION

Study data showed that a high fetal head station, measured using the head-to-perineum distance, and a nonocciput anterior position of the fetal head are independently associated with failed midcavity vacuum-assisted delivery. The result supported the systematic assessment of the sonographic head station and position before performing a midcavity vacuum-assisted delivery.

Traction force profile in children with severe perinatal outcomes delivered with a digital vacuum extraction handle: A case-control study

INTRODUCTION

During the second stage of labor, vacuum-assisted delivery is an alternative to forceps delivery and emergency cesarean section. Extensive research concerning perinatal outcomes has indicated that the risk of complications, although rare, is higher than with a spontaneous vaginal delivery. An important factor related to perinatal outcomes is the traction force applied. Our research group previously developed a digital extraction handle, the Vacuum Intelligent Handle-3 (VIH3), that measures and records traction force. The objective of this study was to compare traction force profiles in children with and without severe perinatal outcomes delivered with the digital handle. A secondary aim was to establish a safe force limit.

MATERIAL AND METHODS

This was an observational case-control study at the delivery ward at Karolinska University Hospital, Sweden. In total, 573 children delivered with the digital handle between 2012 and 2018 were included. Cases were defined as a composite of severe perinatal outcomes, including subgaleal hematoma, intracranial hemorrhage, hypoxic ischemic encephalopathy 1-3, seizures or death. The cases in the cohort were matched 1:3 based on five matching variables. Traction profiles were analyzed using the MATLAB® software and conditional logistic regression.

RESULTS

The incidence of severe perinatal outcomes was 2.3%. The 13 cases were matched with three controls each (n = 39). A statistically significant increased odds for higher total traction forces was seen in the case group (odds ratio [OR] 1.004; 95% confidence interval [CI] 1.001-1.007) and for the peak force (OR 1.022; 95% CI 1.004-1.041). Several procedure-related parameters were significantly increased in the case group. As expected, some neonatal characteristics also differed significantly. An upper force limit of 343 Newton minutes (Nmin) revealed an 86% reduction in severe perinatal outcomes (adjusted OR 0.14; 95% CI 0.04-0.5).

CONCLUSIONS

Children with severe perinatal outcomes had traction force profiles with significantly higher forces. The odds for severe perinatal outcomes increased for every increase in Nmin and Newton used during the extraction procedure. A calculated total force level of 343 Nmin is suggested as an upper safety limit, but this must be tested prospectively to provide validity.

Antepartum ultrasound prediction of failed vacuum-assisted operative delivery: a prospective cohort study

BACKGROUND

Failed vacuum-assisted delivery (VD) is associated with increased risk of maternal perineal trauma and neonatal morbidity. Knowledge of the risk factors related to failed VD is essential in the clinical decision-making.

OBJECTIVE

To elucidate the strength of association and the predictive accuracy of different ante-partum ultrasound parameters in predicting the risk of failed VD prior to the onset of Labor and to test the diagnostic performance of a multiparametric model including pregnancy and Labor characteristics, ante and intra-partum ultrasound in anticipating failed VD.

STUDY DESIGN

Prospective study of consecutive singleton pregnancies complicated by VD undergoing a dedicated ultrasound assessment at 36-38 weeks of gestation. Head circumference (HC), estimated fetal weight (EFW) and subpubic angle and (SPA) were recorded before the onset of Labor. At the time of the VD, occiput position, head perineum distance (HPD) and angle of progression (AOP) were also recorded. Multivariate logistic regression and area under the curve (AUC) analyses were used to explore the strength of association and test the diagnostic accuracy of different maternal, Labor and ultrasound characteristics in predicting g failed VD.

RESULTS

Four hundred eight pregnancies with successful and 26 with failed VD were included in the analysis. Fetuses experiencing failed VD had a larger HC (1.21 versus 1.07 MoM; p = .0001), a higher EFW z-value (0.56 versus 0.33 z values; p = .002) and a narrower SPA (114 versus 122 p = .0001) compared to those having a successful VD. At multivariable logistic regression analysis, maternal height (aOR 0.89 95% CI 0.76-0.98), nulliparity (aOR: 1.14 95% CI 1.06-1.36), HC MoM (aOR: 1.24 95% CI 1.13-1.55) and SPA angle (aOR: 0.82 95% CI 0.67-0.95), but not EFW (p = .08) were independently associated with failed VD. When intrapartum ultrasound variables were added to the multivariate model, fetal occipital position (aOR: 1.45 95th CI 1.11-1.99) and HPD (aOR: 0.77 95th CI 0.44-0.96) were independently associated with failed VD. A multiparametric model integrating pregnancy and Labor characteristics and ante-partum ultrasound variables had an AUC of 0.837 (95% CI 0.797-0.876) for the prediction of failed VE. The addition of intra-partum ultrasound variables to the prediction model, improved the accuracy for failed VD provided by maternal and antepartum ultrasound characteristics with an AUC of 0.913 (0.888-0.937).

CONCLUSION

Antepartum prediction of failed VD is feasible. HC, SPA but not EFW are independently associated and predictive of failed VD. Adding these variables to a multiparametric model including maternal and intrapartum ultrasound parameters improves the diagnostic accuracy for failed VD.

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.

Operative vaginal delivery: all you should know

Over the last three decades, the decrease in operative vaginal delivery (OVD) has lead to an increase in the rate of cesarean sections, giving rise to intense debate amongst healthcare providers. As the use of vacuum and forceps requires personnel be adequately trained so as to become familiar with the correct use of instruments, the lack of skilled and experienced instructors may well lead to this technique being discarded in the near future. The aim of this study was to review the literature, compare the recommendations from international OVD guidelines and to illustrate the correct technique of obstetrical vacuum and forceps application to promote OVD among clinicians as a safe way of delivery.

Perinatal outcome after vacuum assisted delivery with digital feedback on traction force; a randomised controlled study

Background

Low and mid station vacuum assisted deliveries (VAD) are delicate manual procedures that entail a high degree of subjectivity from the operator and are associated with adverse neonatal outcome. Little has been done to improve the procedure, including the technical development, traction force and the possibility of objective documentation. We aimed to explore if a digital handle with instant haptic feedback on traction force would reduce the neonatal risk during low or mid station VAD.

Methods

A two centre, randomised superiority trial at Karolinska University Hospital, Sweden, 2016–2018. Cases were randomised bedside to either a conventional or a digital handle attached to a Bird metal cup (50 mm, 80 kPa). The digital handle measured applied force including an instant notification by vibration when high levels of traction force were predicted according to a predefined algorithm. Primary outcome was a composite of hypoxic ischaemic encephalopathy, intracranial haemorrhage, seizures, death and/or subgaleal hematoma. Three hundred eighty low and mid VAD in each group were estimated to decrease primary outcome from six to 2 %.

Results

After 2 years, an interim analyse was undertaken. Meeting the inclusion criteria, 567 vacuum extractions were randomized to the use of a digital handle (n = 296) or a conventional handle (n = 271). Primary outcome did not differ between the two groups: (2.7% digital handle vs 2.6% conventional handle). The incidence of primary outcome differed significantly between the two delivery wards (4% vs 0.9%, p < 0.05). A recalculation of power revealed that 800 cases would be needed in each group to show a decrease in primary outcome from three to 1 %. This was not feasible, and the study therefore closed.

Conclusions

The incidence of primary outcome was lower than estimated and the study was underpowered. However, the difference between the two delivery wards might reflect varying degree of experience of the technical equipment. An objective documentation of the extraction procedure is an attractive alternative in respect to safety and clinical training. To demonstrate improved safety, a multicentre study is required to reach an adequate cohort. This was beyond the scope of the study.

Trial registration

ClinicalTrials.gov NCT03071783, March 1, 2017, retrospectively registered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03604-z.

Transabdominal and transperineal ultrasound vs routine care before instrumental vaginal delivery - A randomized controlled trial

INTRODUCTION

The role of intrapartum ultrasound as an ancillary method to instrumental vaginal delivery is yet to be determined. This study aimed to compare the use of transabdominal and transperineal ultrasound with routine clinical care before performing an instrumental vaginal delivery, regarding the incidence of adverse maternal and neonatal outcomes.

MATERIAL AND METHODS

A randomized controlled trial was conducted between October 2016 and March 2019 in two tertiary care maternity hospitals in Lisbon, Portugal. Women at term, with full cervical dilatation, singleton fetuses in cephalic presentation, and with an established indication for instrumental vaginal delivery, were approached for enrollment. After informed consent was obtained, randomization into one of two groups was carried out. In the experimental arm, women underwent transabdominal ultrasound for determination of the fetal head position and transperineal ultrasound for evaluation of the angle of progression, before instrumental vaginal delivery. In the control arm, no ultrasound was carried out before instrumental vaginal delivery. Primary outcomes were composite measures of maternal and neonatal morbidity. Composite maternal morbidity consisted of severe postpartum hemorrhage, perineal trauma, and prolonged hospital stay. Composite neonatal morbidity consisted of low 5-minute Apgar score, umbilical artery metabolic acidosis, birth trauma, and neonatal intensive care unit admission.

RESULTS

A total of 222 women were enrolled (113 in the experimental arm and 109 in the control arm). No significant differences between the two arms were found in composite measures of maternal (23.9% in the experimental group vs 22.9% in the control group, odds ratio 1.055, 95% CI 0.567-1.964) or neonatal morbidity (9.7% in the experimental group vs 6.4% in the control group, odds ratio 1.571, 95% CI 0.586-4.215), nor in any of the individual outcomes.

CONCLUSIONS

In this small randomized controlled trial that was stopped for futility before reaching the required sample size, transabdominal and transperineal ultrasound performed just before instrumental vaginal delivery did not reduce the incidence of adverse maternal and neonatal outcomes, when compared with routine clinical care.

Risk factors for neonatal brachial plexus palsy: a systematic review and meta-analysis

AIM

To provide a comprehensive update on the most prevalent, significant risk factors for neonatal brachial plexus palsy (NBPP).

METHOD

Cochrane CENTRAL, MEDLINE, Web of Science, Embase, and ClinicalTrials.gov were searched for relevant publications up to March 2019. Studies assessing risk factors of NBPP in relation to typically developing comparison individuals were included. Meta-analysis was performed for the five most significant risk factors, on the basis of the PRISMA statement and MOOSE guidelines. Pooled odds ratios (ORs), 95% confidence intervals (CIs), and across-study heterogeneity (I² ) were reported. Reporting bias and quality of evidence was rated. In addition, we assessed the incidence of NBPP.

RESULTS

Twenty-two observational studies with a total sample size of 29 419 037 live births were selected. Significant risk factors included shoulder dystocia (OR 115.27; 95% CI 81.35-163.35; I² =92%), macrosomia (OR 9.75; 95% CI 8.29-11.46; I² =70%), (gestational) diabetes (OR 5.33; 95% CI 3.77-7.55; I² =59%), instrumental delivery (OR 3.8; 95% CI 2.77-5.23; I² =77%), and breech delivery (OR 2.49; 95% CI 1.67-3.7; I² =70%). Caesarean section appeared as a protective factor (OR 0.13; 95% CI 0.11-0.16; I² =41%). The pooled overall incidence of NBPP was 1.74 per 1000 live births. It has decreased in recent years.

INTERPRETATION

The incidence of NBPP is decreasing. Shoulder dystocia, macrosomia, maternal diabetes, instrumental delivery, and breech delivery are risk factors for NBPP. Caesarean section appears as a protective factor.

WHAT THIS PAPER ADDS

The overall incidence of neonatal brachial plexus palsy is 1.74 per 1000 live births. The incidence has declined significantly. Shoulder dystocia, macrosomia, maternal diabetes, instrumental delivery, and breech delivery are the main risk factors. Prevention is difficult owing to unpredictability and often labour-related risk.

SMFM Special Statement: Operative vaginal delivery: checklists for performance and documentation

The frequency of operative vaginal delivery has been declining, even though it can be an attractive alternative to cesarean delivery in selected cases. Performance of operative vaginal delivery required consideration of many indications, contraindications, and prerequisites. Optimal documentation of operative vaginal delivery requires the recording of several specific elements that are unique to forceps or vacuum delivery. A cognitive aid such as a checklist is well suited to this situation in which there are numerous elements to consider, a low frequency of performance, and teams with variable expertise. We propose 2 checklists to help ensure that all relevant elements are considered for every operative vaginal delivery: (1) a checklist for preparation and performance of the procedure and (2) a checklist for documentation. We suggest practical tips to help facilities adapt these checklists to their own circumstances and implement them on their units.

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.

[How to proceed after a failed vacuum delivery]

OBJECTIVES

Compare maternal and neonatal morbidity in patients delivered by a second instrument versus cesarean section after failed vacuum.

METHODS

We performed a retrospective study between January 2006 and December 2014. Case notes of 172 failed vacuum deliveries were studied. The studied parameters were blood loss, perineal tears, pH, Apgar score, neonatal reanimation and length of stay in neonatology.

RESULTS

The frequency of vacuum failure was 8.7%. The use of the second instrument (77.9%) was associated with a higher prevalence of third degree perineal tears (13.4% vs. 0%; P=0.017) and more episiotomy (72.2% vs. 0%; P<0.0001). There was no significant difference regarding post partum hemorrhage between cesarean section and second instrument delivery. There was no significant difference regarding neonatal morbidity between cesarean section and second instrument delivery after failed vacuum. When an attempted second instrument delivery failed, the risk of adverse neonatal outcome was increased: newborns had a significantly longer stay in a neonatal unit (2.4 versus 0.6 days; P=0.026), lower pH (P=0.017), lower Apgar scores (7.4 versus 8.8; P=0.0373), needed intubation (P=0.0471) and had seizures (P=0.04) more often.

CONCLUSION

Compared to cesarean section, the use of the second instrument increased maternal morbidity but doesn't seem to increase neonatal morbidity. If the second instrument fails, neonatal morbidity is significantly increased.

Simulation TRaining for Operative vaginal Birth Evaluation: study protocol for an observational stepped-wedge interrupted time-series study (STROBE)

BACKGROUND

Operative vaginal birth is a common procedure used to expedite birth after full cervical dilatation where there is a clinical need to do so (15% of births in the UK in 2016). The acquisition of skills for operative vaginal birth is dependent on the exposure of junior obstetricians to situations in which they can undertake directly supervised learning from senior accouchers. The Royal College of Obstetricians and Gynaecologists has recently introduced the first structured course in operative vaginal birth. To date, there have been no attempts to determine the clinical impact of a structured training package for operative vaginal birth.

METHODS

The STROBE study is a quasi-experimental before-after interrupted time-series study of the effect of simulation training in operative vaginal birth for obstetricians on clinical outcomes of women and babies following operative vaginal birth. Similar to a stepped-wedge design, the intervention will be gradually implemented in all participating units but at different time periods. The primary outcome is failed operative vaginal birth with the first intended instrument. Secondary maternal outcomes are; use of second instrument to achieve operative vaginal birth, caesarean section, episiotomy, perineal trauma (1st, 2nd, 3rd, 4th degree tear), cervical tear requiring suturing, general anaesthesia and estimated blood loss. Secondary neonatal outcomes are; Apgar score at one, five, and ten minutes, Umbilical artery pH, shoulder dystocia, admission to Neonatal Intensive Care Unit and death within 28 days of birth. The analysis will be intention-to-treat (per unit) on the primary and secondary outcomes. The STROBE study received approval from the Health Research Authority and is sponsored by North Bristol NHS Trust. Results will be published in an open-access peer-reviewed medical journal within one year of completion of data gathering.

DISCUSSION

The STROBE study will help establish our understanding of the effectiveness of locally-delivered simulation training for operative vaginal birth. Robust evidence supporting the effectiveness of such an approach would add weight to the argument supporting regular, local training for junior obstetricians in operative vaginal birth.

TRIAL REGISTRATION

ISRCTN11760611 05/03/2018 (retrospectively registered).

Effect of team training and monitoring on the rate of failed mid and low cavity vacuum extraction: a hospital based intervention study

BACKGROUND

Clinical team training has been advocated as a means to improve delivery care, and failed extractions is a suggested variable for clinical audit in instrumental vaginal delivery. Other activities may also have intended or unintended effects on care processes or outcomes.

METHODS

We retrospectively observed 1074 mid and low vacuum extraction deliveries during three time periods (prevalence periods): Baseline (period 0), implemented team training (period 1 and 2) and monitoring of traction force during vacuum extraction (period 2). Our primary outcome was failed extraction followed by emergency cesarean section or obstetric forceps delivery.

RESULTS

The prevalence proportion (relative risk) of failed extraction decreased significantly after implementation of team training, from 19% (period 0) to 8 % (period 1), corresponding to a relative risk of 0.48 [0.26-0.87]. The secondary procedural outcome complicated delivery (duration > 15 min or number of pulls > 6, or cup detachment > 1) was decreased in period 2 compared to period 1, RR 0.42 [0.23-0.76]. Secondary clinical (neonatal) outcome were not affected.

CONCLUSION

Clinically based educational efforts and increased monitoring improved procedural outcome without improving neonatal outcome. The study design has inherent limitations in making causal inference.

Nontechnical skills and decision making in operative vaginal delivery

Nontechnical skills are defined as social, cognitive and personal resource skills that are necessary to conduct any technical skill safely. Whilst the skills are categorised into three domains: social, cognitive and personal resources, these are dependent on each other and the development and effectiveness of one relies on the other two. Effective nontechnical skills are essential in the safe care of patients in any setting, and their importance can be clearly demonstrated in the safe development of skills in many areas of medicine and surgery. Increasingly the importance of these skills is being recognised in outcomes for patients and staff, and training courses and assessment tools are being developed and used in obstetrics. Understanding of the role of nontechnical skills in labour and especially in operative vaginal births should be embedded across the specialty. Further research is needed in validation of assessment tools for these skills when used in obstetrics.

"Strategies to increase the accuracy and safety of OVD" (Clinical assessment skills and role of ultrasound, simulation training and new technologies to enhance instrument application)

Operative vaginal delivery (OVD) is commonly performed in the UK and Ireland. With skillful practice, the risks to mothers and babies are low. Caesarean section at full dilatation, particularly after failed OVD, can be more hazardous for mothers and babies. It is important to maintain and develop skills in OVD in order to provide it as a safe delivery option when the benefits outweigh the risks. As ultrasound machines have become more readily available on the labour ward, ultrasound assessment has been used to help clinicians diagnose the fetal head position and station, and also to try predict the success of the delivery. Simulation training has successfully been used in the setting of obstetric emergencies and is being developed to teach both technical and communication skills in OVD in order to improve maternal and neonatal outcomes. In this chapter we will discuss strategies to improve the accuracy and safety of OVD in more details.

[Pathophysiology, diagnosis and management of occiput posterior presentation during labor]

Persistant occiput posterior (OP) positions are the commonest malpresentations of the fetal head during labor and their diagnosis remains challenging. They are associated to prolonged second stage of labor, prolonged expulsive efforts, labor augmentation, cesarean sections and instrumental deliveries. On the maternal side, severe perineal tears, post-partum hemorrhage or chorioamnionitis are more frequent. Currently, prevention of persistent OP positions is based on the maintain of precise maternal positions. Several positions have been evaluated but only lateral position on the same side of the fetal spine has proved its effectiveness. Fetal head rotation can also be achieved with extraction instruments though none has ever been evaluated by a randomized controlled trial. Obstetrical forceps seem more efficient than vacuum but are associated with severe perineal tears. Evaluation of rotation with Thierry's spatulas is scarce. Last, manual rotation is of routine use in many wards. This management is associated with a twofold reduction of operative delivery rate and rare adverse outcomes but has never been evaluated through randomized control trial.

Vacuum extraction failure is associated with a large head circumference

Objective: To determine whether large head circumference increases the risk of vacuum extraction failure. Study design: This EMR-based study included all attempted vacuum extractions performed in a tertiary center between January 2010 and June 2015. All term singleton live births were eligible. Cases were divided into four groups: head circumference ≥90th percentile both with birth weight ≥90th percentile and <90th percentile and fetal head circumference <90th percentile with birth weight ≥90th and <90th percentile. Risk of failed vacuum extraction was compared among these groups. Other neonatal and maternal parameters were also evaluated as potential risk factors. Multinomial multivariable regression provided adjusted odds ratio for vacuum extraction failure while controlling for potential confounders. Results: During the study period, 48,007 deliveries met inclusion criteria, of which 3835 had an attempt at vacuum extraction. We identified 215 (5.6%) cases of vacuum extraction failure. The adjusted odds ratios (aOR) for vacuum extraction failure in cases of large fetal head circumference was 2.31 (95%CI, 1.7-3.15, p < .001). Primiparity, prolonged second stage and occipito-posterior presentation were also found to be significant risk factors for failed vacuum extraction. Comments: In this study, we found that large head circumference was associated with vacuum extraction failure rather than high birth weight.

Angle of fetal head progression measured using transperineal ultrasound as a predictive factor of vacuum extraction failure

OBJECTIVE

To evaluate the predictive value of angle of progression (AoP) of the fetal head for a failed vacuum delivery.

METHODS

This was a prospective observational study that included women with a singleton pregnancy of ≥ 37 weeks' gestation, in cephalic presentation requiring vacuum extraction. Transperineal ultrasound was performed immediately before vacuum extraction, although AoP was measured on stored images after delivery. Vacuum extraction was defined as failed when the duration of extraction exceeded 20 min or the vacuum cup detached more than three times. We compared the demographic and ultrasound data of failed vacuum deliveries with those that were successful. The predictive value of AoP for failure of vacuum delivery was calculated.

RESULTS

AoP was measured in 235 women. Vacuum extractions failed in 30 (12.8%) women (29/184 nulliparous and 1/51 parous) and resulted in 28 vaginal deliveries by forceps and two Cesarean deliveries. Median AoP was significantly lower in the vacuum failure group compared with those with successful vacuum delivery (136.6° (interquartile range (IQR), 129.8-144.1°) vs 145.9° (IQR, 135.0-158.4°); P < 0.01). As all but one failed vacuum extraction occurred among nulliparous women, the predictive value of AoP was calculated in this subgroup of women. The area under the receiver-operating characteristics curve for prediction of vacuum extraction failure was 0.67 (95% CI, 0.57-0.77) and the optimal AoP cut-off was 145.5°. Above this value, the rate of vacuum extraction failure fell below 5%.

CONCLUSION

AoP is a predictive factor of failed vacuum extraction, especially among nulliparous women whose risk of failure is high. AoP measurement may help in choosing between forceps and vacuum extraction. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Obstetrical Anal Sphincter Injuries (OASIS): Prevention, Recognition, and Repair

OBJECTIVE

To review the evidence relating to obstetrical anal sphincter injuries (OASIS) with respect to diagnosis, repair techniques and outcomes. To formulate recommendations as to patient counselling regarding route of delivery for subsequent pregnancy after OASIS.

OPTIONS

Obstetrical care providers caring for women with OASIS have the option of repairing the anal sphincter using end-to-end or overlapping techniques. They may also be involved in counselling women with prior OASIS regarding the route of delivery for future pregnancies.

OUTCOMES

The outcome measured is anal continence following primary OASIS repair and after subsequent childbirth.

EVIDENCE

Published literature was retrieved through searches of Medline, EMBASE, and The Cochrane Library in May 2011 using appropriate controlled vocabulary (e.g., anal canal, obstetrics, obstetric labour complication, pregnancy complication, treatment outcome, surgery, quality of life) and key words (obstetrical anal sphincter injur*, anus sphincter, anus injury, delivery, obstetrical care, surgery, suturing method, overlap, end-to-end, feces incontinence). Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational. There were no date or language restrictions. Searches were updated on a regular basis and incorporated in the guideline to September 2014. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALUES

The quality of evidence in this document was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care (Table 1).

BENEFITS, HARMS, AND COSTS

Benefits from implementation of these guidelines include: improved diagnosis of OASIS, optimal functional outcomes following repair, and evidence-based counselling of women for future childbirth.

Transverse occiput position: Using manual Rotation to aid Normal birth and improve delivery OUTcomes (TURN-OUT): A study protocol for a randomised controlled trial

BACKGROUND

Fetal occiput transverse position in the form of deep transverse arrest has long been associated with caesarean section and instrumental vaginal delivery. Occiput transverse position incidentally found in the second stage of labour is also associated with operative delivery in high risk cohorts. There is evidence from cohort studies that prophylactic manual rotation reduces the caesarean section rate. This is a protocol for a double blind, multicentre, randomised, controlled clinical trial to define whether this intervention decreases the operative delivery (caesarean section, forceps or vacuum delivery) rate.

METHODS/DESIGN

Eligible participants will be ≥37 weeks pregnant, with a singleton pregnancy, and a cephalic presentation in the occiput transverse position on transabdominal ultrasound early in the second stage of labour. Based on a background risk of operative delivery of 49%, for a reduction to 35%, an alpha value of 0.05 and a beta value of 0.2, 416 participants will need to be enrolled. Participants will be randomised to either prophylactic manual rotation or a sham procedure. The primary outcome will be operative delivery. Secondary outcomes will be caesarean section, significant maternal mortality and morbidity, and significant perinatal mortality and morbidity. Analysis will be on an intention-to-treat basis. Primary and secondary outcomes will be compared using a chi-squared test. A logistic regression for the primary outcome will be undertaken to account for potential confounders. This study has been approved by the Ethics Review Committee (RPAH Zone) of the Sydney Local Health District, Sydney, Australia, (protocol number: X110410).

DISCUSSION

This trial addresses an important clinical question concerning a commonly used procedure which has the potential to reduce operative delivery and its associated complications. Some issues discussed in the protocol include methods of assessing risk of bias due to inadequate masking of a procedural interventions, variations in intervention efficacy due to operator experience and the recruitment difficulties associated with intrapartum studies.

TRIAL REGISTRATION

This trial was registered with the Australian New Zealand Clinical Trials Registry (identifier: ACTRN12613000005752 ) on 4 January 2013.

Obstetric anal sphincter injuries: review of anatomical factors and modifiable second stage interventions

INTRODUCTION AND HYPOTHESIS

Obstetric anal sphincter injuries (OASIs) are the leading cause of anal incontinence in women. Modification of various risk factors and anatomical considerations have been reported to reduce the rate of OASI.

METHODS

A PubMed search (1989-2014) of studies and systematic reviews on risk factors for OASI.

RESULTS

Perineal distension (stretching) of 170 % in the transverse direction and 40 % in the vertical direction occurs at crowning, leading to significant differences (15-30°) between episiotomy incision angles and suture angles. Episiotomies incised at 60° achieve suture angles of 43-50°; those incised at 40° result in a suture angle of 22°. Episiotomies with suture angles too acute (<30°) and too lateral (>60°) are associated with an increased risk of OASI. Suture angles of 40-60° are in the safe zone. Clinicians are poor at correctly estimating episiotomy angles on paper and in patients. Sutured episiotomies originating 10 mm away from the midline are associated with a lower rate of OASIs. Compared to spontaneous tears, episiotomies appear to be associated with a reduction in OASI risk by 40-50 %, whereas shorter perineal lengths, perineal oedema and instrumental deliveries are associated with a higher risk. Instrumental deliveries with mediolateral episiotomies are associated with a significantly lower OASI risk. Other preventative measures include warm perineal compresses and controlled delivery of the head.

CONCLUSIONS

Relieving pressure on the central posterior perineum by an episiotomy and/or controlled delivery of the head should be important considerations in reducing the risk of OASI. Episiotomies should be performed 60° from the midline. Prospective studies should evaluate elective episiotomies in women with a short perineal length and application of standardised digital perineal support.

Kielland's forceps: does it increase the risk of anal sphincter injuries? An observational study

INTRODUCTION AND HYPOTHESIS

Rotational instrumental deliveries are thought to carry additional risks compared with non-rotational instrumental deliveries, including trauma to maternal tissues, and require specific expertise and training. We conducted a retrospective study to investigate the association between the type of forceps delivery and maternal perineal trauma, and in particular to investigate if Kielland's rotational forceps delivery increases obstetric anal sphincter injuries (OASIS).

METHODS

This is a retrospective observational study of 1,515 women who attended a tertiary maternity unit over a period of 5 years and had operative vaginal deliveries primarily or completed by forceps. Data were obtained through the hospital's maternity reporting system. The severity of maternal perineal trauma, particularly third and fourth-degree tears in relation to the type of forceps delivery was explored. Multinomial logistic regression models were used to estimate the crude and the adjusted relative risks (RR) of sustaining third-degree tears compared with other types of vaginal tears. Univariate analyses explored the crude associations between relative risks and age, ethnicity, birth weight, type of instrumental delivery and operator's experience. A multivariate multinomial logistic regression model estimated the adjusted relative risks and included all the previous variables as independent covariates.

RESULTS

Of the 1,492 women included in the study, 150 women (77 %) had sustained category 1 tears, 63 women (4 %) had sustained category 2 tears and 279 women (19 %) had sustained third-degree tears. There was no statistically significant association between the severity of maternal perineal trauma and the type of forceps delivery (failed ventouse vs Kielland's forceps RR 1.52, p = 0.159 CI 0.84-2.72, Wrigleys vs Kielland's RR 0.59, p = 0.249, CI 0.24-1.43; Andersons vs Kielland's RR 1.16, p = 0.603, CI 0.65-2.05) after adjusting for age, birth weight, BMI, ethnicity and operator experience (full list of covariates not included).

CONCLUSIONS

The incidence of third- and fourth-degree tears following rotational Kielland's forceps delivery and other non-rotational forceps deliveries is comparable.

Persistent Occiput Posterior position - OUTcomes following manual rotation (POP-OUT): study protocol for a randomised controlled trial

BACKGROUND

Occiput posterior position is the most common malpresentation in labour, contributes to about 18% of emergency caesarean sections and is associated with a high risk of assisted delivery. Caesarean section is now a major contributing factor to maternal mortality and morbidity following childbirth in developed countries. Obstetric intervention by forceps and ventouse delivery is associated with complications to the maternal genital tract and to the neonate, respectively. There is level 2 evidence that prophylactic manual rotation reduces the caesarean section rate and assisted vaginal delivery. But there has been no adequately powered randomised controlled trial. This is a protocol for a double-blinded, multicentre, randomised controlled clinical trial to define whether this intervention decreases the operative delivery (caesarean section, forceps or vacuum delivery) rate.

METHODS/DESIGN

Eligible participants will be (greater than or equal to) 37 weeks' with a singleton pregnancy and a cephalic presentation in the occiput posterior position on transabdominal ultrasound early in the second stage of labour. Based on a background risk of operative delivery of 68%, then for a reduction to 50%, an alpha value of 0.05 and a beta value of 0.2, 254 participants will need to be enrolled. This study has been approved by the Ethics Review Committee (RPAH Zone) of the Sydney Local Health District, Sydney, Australia, and protocol number X110410. Participants with written consent will be randomised to either prophylactic manual rotation or a sham procedure. The primary outcome will be operative delivery (defined as vacuum, forceps and/or caesarean section deliveries). Secondary outcomes will be caesarean section, significant maternal mortality/morbidity and significant perinatal mortality/morbidity. Analysis will be by intention-to-treat. Primary and secondary outcomes will be compared using a chi-squared test. A logistic regression for the primary outcome will be undertaken to account for potential confounders. The results of the trial will be presented at one or more medical conferences. The trial will be submitted to peer review journals for consideration for publication. There will be potential to incorporate the results into professional guidelines for obstetricians and midwives.

TRIAL REGISTRATION

The Australian New Zealand Clinical Trials Registry ACTRN12612001312831 . Trial registered 12 December 2012.

A prospective cohort study of the morbidity associated with operative vaginal deliveries performed by day and at night

OBJECTIVE

To evaluate maternal and neonatal outcomes associated with operative vaginal deliveries (OVDs) performed by day and at night.

DESIGN

Prospective cohort study.

SETTING

Urban maternity unit in Ireland with off-site consultant staff at night.

POPULATION

All nulliparous women requiring an OVD with a term singleton fetus in a cephalic presentation from February to November 2013.

METHODS

Delivery outcomes were compared for women who delivered by day (08:00-19:59) or at night (20:00-07:59).

MAIN OUTCOME MEASURES

The main outcomes included postpartum haemorrhage (PPH), anal sphincter tear and neonatal unit admission. Procedural factors included operator grade, sequential use of instruments and caesarean section.

RESULTS

Of the 597 women who required an OVD, 296 (50%) delivered at night. Choice of instrument, place of delivery, sequential use of instruments and caesarean section did not differ significantly in relation to time of birth. Mid-grade operators performed less OVDs by day than at night, OR 0.60 (95% CI 0.43 to 0.83), and a consultant supervisor was more frequently present by day, OR 2.26 (95% CI 1.05 to 4.83). Shoulder dystocia occurred more commonly by day, OR 2.57 (95% CI 1.05 to 6.28). The incidence of PPH, anal sphincter tears, neonatal unit admission, fetal acidosis and neonatal trauma was similar by day and at night. The mean decision to delivery intervals were 12.0 and 12.6 min, respectively.

CONCLUSIONS

There was no evidence of an association between time of OVD and adverse perinatal outcomes despite off-site consultant obstetric support at night.

Increasing rates of operative vaginal delivery across two decades: accompanying outcomes and instrument preferences

OBJECTIVE

To examine rates and outcomes of operative vaginal delivery over a 20-year study period and the changing preference for various instruments during this period.

STUDY DESIGN

This retrospective analysis of prospectively gathered data was carried out at a large tertiary referral center from 1991 to 2010. All cases of operative vaginal delivery during the study period were recorded. The rates of instrumental delivery, as well as neonatal outcomes and instrument preference, were compared for individual 5-year epochs.

RESULTS

During the study period there were 156,130 deliveries of which 17,841 were operative vaginal deliveries, an incidence of 11.4/100 deliveries and 13.6/100 vaginal deliveries. There was an increase in the rate of operative vaginal delivery across the 20-year period (P < 0.0001; R(2) = 0.85; Slope = 0.42). When individual 5-year epochs were compared, the incidence of instrumental delivery increased from 7.3% (2340/31,937) in the first five years, 1991-1995, to 13.7% (6179/45,177) in the final five years, 2006-2010 (P < 0.0001; OR 2.34, 95% CI = 2.23-2.47). The perinatal mortality rate in cases of instrumental delivery was decreased when these time periods were compared (7.3/1000 (17/2340) vs. 1.8/1000 (11/6179); P = 0.003, OR 0.24, 95% CI = 0.11-0.52). The choice of instrument also varied, with 68.2% (1596/2340) of instrumental deliveries in 1991-1995 being carried out with forceps compared to 32.9% (2033/6179) in 2006-2010 (P < 0.001).

CONCLUSION

Rates of operative vaginal delivery have increased over the 20-year study period. The rate of perinatal mortality in infants who had an assisted vaginal delivery was decreased in the 5-year epoch at the end of the study compared with the period at the beginning. The rate of forceps delivery has fallen significantly, with vacuum delivery now being the choice of the majority of clinicians.

Is it Time to Rejuvenate the Forceps?

The obstetric forceps was designed to assist extraction of the foetal head and thereby accomplish delivery of the foetus in the second stage of labour. More than 700 types of obstetric forceps have been described. An understanding of the anatomy of the birth canal and the foetal head is a prerequisite to becoming a skilled and safe user of forceps. Operative vaginal delivery rates have remained stable at between 10 and 13 %. The last few decades has seen a rise in caesarean section, along with the introduction and safe use of the vacuum extractor. This has resulted in a decline both in the use of the obstetric forceps as well as in the training for the same. The forceps is less likely to fail when used as the primary instrument thereby reducing the need for the sequential use of two instruments which increase the morbidity of the neonate. Perineal trauma is more likely to occur with the use of the forceps but the evidence is that the maternal concern is less when compared to the ventouse. Simulation training is an important part of obstetric training. Application of forceps blades in the simulation setting can improve the skill level of obstetricians. The use of the forceps should not be decreasing and more senior involvement in training is necessary so that juniors develop the proper skills to perform forceps delivery in a competent and safe manner. It is vital that the art of the forceps is not lost to future generations of obstetricians and the women they care for.