Operator experience affects the risk of obstetric anal sphincter injury in vacuum extraction deliveries

Lateral episiotomy or no episiotomy in vacuum assisted delivery in nulliparous women (EVA): multicentre, open label, randomised controlled trial

OBJECTIVE

To assess the effect of lateral episiotomy, compared with no episiotomy, on obstetric anal sphincter injury in nulliparous women requiring vacuum extraction.

DESIGN

A multicentre, open label, randomised controlled trial.

SETTING

Eight hospitals in Sweden, 2017-23.

PARTICIPANTS

717 nulliparous women with a single live fetus of 34 gestational weeks or more, requiring vacuum extraction were randomly assigned (1:1) to lateral episiotomy or no episiotomy using sealed opaque envelopes. Randomisation was stratified by study site.

INTERVENTION

A standardised lateral episiotomy was performed during the vacuum extraction, at crowning of the fetal head, starting 1-3 cm from the posterior fourchette, at a 60° (45-80°) angle from the midline, and 4 cm (3-5 cm) long. The comparison was no episiotomy unless considered indispensable.

MAIN OUTCOME MEASURES

The primary outcome of the episiotomy in vacuum assisted delivery (EVA) trial was obstetric anal sphincter injury, clinically diagnosed by combined visual inspection and digital rectal and vaginal examination. The primary analysis used a modified intention-to-treat population that included all consenting women with attempted or successful vacuum extraction. As a result of an interim analysis at significance level P<0.01, the primary endpoint was tested at 4% significance level with accompanying 96% confidence interval (CI).

RESULTS

From 1 July 2017 to 15 February 2023, 717 women were randomly assigned: 354 (49%) to lateral episiotomy and 363 (51%) to no episiotomy. Before vacuum extraction attempt, one woman withdrew consent and 14 had a spontaneous birth, leaving 702 for the primary analysis. In the intervention group, 21 (6%) of 344 women sustained obstetric anal sphincter injury, compared with 47 (13%) of 358 women in the comparison group (P=0.002). The risk difference was -7.0% (96% CI -11.7% to -2.5%). The risk ratio adjusted for site was 0.47 (96% CI 0.23 to 0.97) and unadjusted risk ratio was 0.46 (0.28 to 0.78). No significant differences were noted between groups in postpartum pain, blood loss, neonatal outcomes, or total adverse events, but the intervention group had more wound infections and dehiscence.

CONCLUSIONS

Lateral episiotomy can be recommended for nulliparous women requiring vacuum extraction to significantly reduce the risk of obstetric anal sphincter injury.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02643108.

Factors Associated with Obstetric Anal Sphincter Injury During Vacuum-Assisted Vaginal Delivery

INTRODUCTION AND HYPOTHESIS

Obstetric anal sphincter injury (OASI) is a major complication associated with vacuum-assisted vaginal delivery (VAVD). The aim of this study was to evaluate risk factors related to vacuum extraction that are associated with OASI.

METHODS

This was a case-control study performed at a tertiary university teaching hospital. Included were patients aged 18-45 years who had a singleton pregnancy resulting in a live, term, VAVD. The study group consisted of women diagnosed with OASI following vacuum extraction. The control group included women following VAVD without OASI. Matching at a ratio of 1:2 was performed. Groups were compared regarding demographic, obstetric. and labor-related parameters, specifically focusing on variables related to the vacuum procedure itself.

RESULTS

One hundred and ten patients within the study group and 212 within the control group were included in the final analysis. Patients in the OASI group were more likely to undergo induction of labor, use of oxytocin during labor, increased second stage of labor, higher likelihood of the operator being a resident, increased number of pulls, procedure lasting under 10 min, occipito-posterior head position at vacuum initiation, episiotomy, increased neonatal head circumference, and birthweight. Multivariate logistic regression analysis revealed that increased week of gestation (OR 1.67, 95% CI 1.25-2.22, p < 0.001), unsupervised resident performing the procedure (OR 4.63, 95% CI 2.17-9.90), p < 0.001), indication of VAVD being fetal distress (OR 2.72, 95% CI 1.04-7.10, p = 0.041), and length of procedure under 10 min (OR 4.75, 95% CI 1.53-14.68, p = 0.007) were associated with OASI. Increased maternal age was associated with lower risk of OASI (OR 0.9, 95% CI 0.84-0.98, p = 0.012).

CONCLUSIONS

When performing VAVD, increased week of gestation, unsupervised resident performing the procedure, fetal distress as vacuum indication, and vacuum procedure under 10 min were associated with OASI. In contrast, increased maternal age was shown to be a protective factor.

Do doctors preferring forceps encounter more obstetric anal sphincter injuries: A retrospective analysis

BACKGROUND

Obstetric anal sphincter injuries (OASIS) is a hospital-acquired injury and can affect a woman's quality of life with problems such as anal incontinence, perineal pain, dyspareunia, mental health, psychosexual issues, and concerns about future childbirth choices.

AIMS

The aim of this study was to determine whether there is a correlation between a doctor's preference for instruments, their individual OASIS rate and whether factors such as their fully dilated caesarean section rate, rate of double instrumental and seniority, influences their individual rate of OASIS.

MATERIALS AND METHODS

A population-based retrospective cohort study was performed on 1340 term nulliparous women with singleton pregnancies who underwent an instrumental delivery or fully dilated caesarean section. A survey of doctors involved in these deliveries was performed. The risk of OASIS was analysed for maternal age, ethnicity, birth position, level of training and doctor's instrument preference using a generalised linear mixed model. Doctors' instrument preferences were established in two ways: a self-reported survey and data-inferred preference based on the most used instrument per doctor. The OASIS rate for individual doctors was calculated.

RESULTS

The overall risk of OASIS is higher for forceps compared to vacuum deliveries. Doctors with a preference for forceps compared to vacuum, correlated with both a lower OASIS rate and a higher fully dilated caesarean section rate.

CONCLUSIONS

Doctors preferring forceps report a lower OASIS and higher fully dilated caesarean section rate. Doctors preferring vacuum must consider carefully whether forceps should follow if a vacuum fails as OASIS is more likely to occur.

Attitudes and knowledge regarding episiotomy use and technique in vacuum extraction: A web-based survey among doctors in Sweden

OBJECTIVES

Correct episiotomy use and technique may prevent obstetric anal sphincter injuries. We aimed to explore the attitudes, use, and technique regarding episiotomy among doctors in Sweden, and their willingness to contribute to a randomized controlled trial of lateral episiotomy or no episiotomy in vacuum extraction in nulliparous women.

STUDY DESIGN

A web-based survey was sent to members of the Swedish Society of Obstetrics and Gynecology (n = 2140). The survey included 31 questions addressing personal characteristics, use of episiotomy, a two-dimensional picture on which the respondents drew an episiotomy, and questions regarding attitudes towards episiotomy and participation in a randomized controlled trial. We calculated the proportion of supposedly protective episiotomies (fulfilling criteria of a lateral or mediolateral episiotomy and a length ≥ 30 mm). We compared the results between obstetricians, gynecologists, and residents using Chi-square and Kruskal-Wallis tests for differences between groups, and logistic regression to estimate the odds ratio (OR) of drawing a protective episiotomy.

RESULTS

We received 432 responses. Doctors without a vacuum delivery in the past year were excluded, leaving 384 respondents for further analyses. In all, 222 (57.8%) doctors reported use of episiotomy in<50% of vacuum extractions. We obtained 308 illustrated episiotomies with a median angle of 53°, incision point distance from the midline of 21 mm, and length of 36 mm, corresponding to a lateral episiotomy. Few doctors combined these parameters correctly resulting in 167 (54.2%) incorrectly drawn episiotomies. Residents drew shorter episiotomies than obstetricians and gynecologists. Doctors ranked episiotomy the least important intervention to prevent obstetric anal sphincter injuries in vacuum extraction. Doctors contributing to an ongoing randomized controlled trial of lateral episiotomy or no episiotomy in vacuum extraction were more able to draw a protective episiotomy (OR 3.69, 95% confidence interval 1.94-7.02).

CONCLUSIONS

Doctors in Sweden reported restrictive use of episiotomy in vacuum extraction and depicted lateral type episiotomies, although the majority were incorrectly drawn. Preventive episiotomy was ranked of low importance. Our results imply a need for education, training, and guidelines to increase uptake of correct episiotomy technique, which could result in improved prevention of obstetric anal sphincter injuries.

Ultrasound vs routine care before instrumental vaginal delivery: A systematic review and meta-analysis

INTRODUCTION

The objective was to report the role of intrapartum ultrasound examination in affecting maternal and perinatal outcome in women undergoing instrumental vaginal delivery.

MATERIAL AND METHODS

MEDLINE, Embase, CINAHL, Google Scholar and ClinicalTrial.gov databases were searched. Inclusion criteria were randomized controlled trials comparing ultrasound assessment of fetal head position vs routine standard care (digital examination) before instrumental vaginal delivery (either vacuum or forceps). The primary outcome was failed instrumental delivery extraction followed by cesarean section. Secondary outcomes were postpartum hemorrhage, 3rd or 4th degree perineal lacerations, episiotomy, prolonged hospital stay, Apgar score<7 at 5 min, umbilical artery pH <7.0 and base excess greater than -12 mEq, admission to neonatal intensive care unit (NICU), shoulder dystocia, birth trauma, a composite score of adverse maternal and neonatal outcome and incorrect diagnosis of fetal head position. Risk of bias was assessed using the Revised Cochrane risk-of-bias tool for randomized trials (RoB-2). The quality of evidence and strength of recommendations were assessed using the Grading of Recommendations Assessment Development and Evaluation (GRADE) methodology. Head-to-head meta-analyses using a random-effect model were used to analyze the data and results are reported as relative risk with their 95% confidence intervals.

RESULTS

Five studies were included (1463 women). There was no difference in the maternal, pregnancy or labor characteristics between the two groups. An ultrasound assessment prior to instrumental vaginal delivery did not affect the cesarean section rate compared with standard care (p = 0.805). Likewise, the risk of composite adverse maternal outcome (p = 0.428), perineal lacerations (p = 0.800), postpartum hemorrhage (p = 0.303), shoulder dystocia (p = 0.862) and prolonged stay in hospital (p = 0.059) were not different between the two groups. Composite adverse neonatal outcome was not different between the women undergoing and those not undergoing ultrasound assessment prior to instrumental delivery (p = 0.400). Likewise, there was no increased risk with abnormal Apgar score (p = 0.882), umbilical artery pH < 7.2 (p = 0.713), base excess greater than -12 (p = 0.742), admission to NICU (p = 0.879) or birth trauma (p = 0.968). The risk of having an incorrect diagnosis of fetal head position was lower when ultrasound was performed before instrumental delivery, with a relative risk of 0.16 (95% confidence interval 0.1-0.3; I² :77%, p < 0.001).

CONCLUSIONS

Although ultrasound examination was associated with a lower rate of incorrect diagnoses of fetal head position and station, this did not translate to any improvement of maternal or neonatal outcomes.

Temporal trends in obstetric anal sphincter injury from the first vaginal delivery in Austria, Canada, Norway, and Sweden

INTRODUCTION

Obstetric anal sphincter injuries (OASI) are severe complications that can cause considerable short- and long-term morbidity. Austria, Canada, Norway, and Sweden have similar socio-economic characteristics, and all four countries have access to national birth registers. In this study, we hypothesized that the incidence of OASI should be very similar for different obstetric scenarios in these four countries. Therefore, the aim was to compare the incidence of OASI in these four countries in primiparous women, with spontaneous or instrumental delivery (vacuum or forceps), and in women with a first vaginal birth after cesarean section (VBAC).

MATERIAL AND METHODS

Aggregated data on 1 933 930 vaginally delivered primiparous women and women with VBAC were retrieved from the birth registers gathered in Austria, Canada, Norway, and Sweden. The annual rate of OASI (ICD-10 codes O70.2-O70.3) was presented as the percentage of women with a spontaneous delivery, vacuum or forceps delivery, and a VBAC during the period 2004-2016.

RESULTS

The incidence of OASI varied considerably between countries and over time. Canada and Sweden had the highest rates, and Austria and Norway the lowest. In Norway, the rate of OASI decreased consistently for all types of deliveries after introducing a perineal protection program in 2004 (p < 0.001). During vacuum delivery, the incidence of OASI varied between countries from 4.1% to 15.5% across the study period. In Canada and Norway, the rate of OASI after a forceps delivery was similar in 2004 at ~20% and with differing trajectories to 24.3% (β 0.49) and 6.2% (β -1.15) (trend, all p < 0.001) in 2016.

CONCLUSIONS

This comparative register study suggests that there may be considerable potential for lowering the incidence of OASI. The perineal protection program implemented by Norway has been successful. Each country should critically, without prejudice, analyze their current clinical practices and rate of OASI and consider the best preventive strategy.

Simulation training program for vacuum application to improve technical skills in vacuum-assisted vaginal delivery

OBJECTIVE

evaluation of technical skills of the operators during the obstetrical device application for operative vaginal delivery, named kiwi-cup in a simulation training program.

METHODS

Thirty-five residents in obstetrics and gynecology of the University of Pisa, Italy were recruited and evaluated with an assessment scale on technical skills from 0 to 55 points. They performed various operative vaginal delivery simulations with kiwi-cup and were evaluated at time 0 by a tutor. After 8 weeks, simulation training was repeated and trainees were re-evaluated by the same tutor.

RESULTS

after 8 weeks from the first simulation session, trainees have been shown to increase technical skills (46.27 ± 4.6 with p-value < 0.0001), the successful application rate (85.71% with p-value 0.0161).) and to reduce the time to complete the procedure (86.2 ± 29.9 s with p-value < 0.0001).

CONCLUSION

simulation training on operational vaginal delivery significantly increases technical skills, improves successful rate, and reduces the time taken to complete the procedure.

CLINICAL TRIAL REGISTRATION

Not applicable.

Obstetric anal sphincter injury after episiotomy in vacuum extraction: an epidemiological study using an emulated randomised trial approach

OBJECTIVE

To emulate a randomised controlled trial investigating whether lateral or mediolateral episiotomy compared with no episiotomy reduces the prevalence of obstetric anal sphincter injury (OASIS) in nulliparous women delivered with vacuum extraction.

DESIGN

A population-based observational study.

SETTING

Sweden.

POPULATION

63 654 nulliparous women delivered with vacuum extraction derived from the Swedish Medical Birth Register 2000-2011, with a live singleton baby with no known malformations in cephalic presentation in gestational week ≥34⁺⁰ , and subject to lateral or mediolateral episiotomy or no episiotomy.

METHODS

The effect of episiotomy was calculated using a causal doubly robust estimation method based on propensity scores. Results are presented as the average treatment effect and numbers needed to treat (NNT).

MAIN OUTCOME MEASURES

OASIS (third- and fourth-degree perineal injury) in nulliparous women delivered with vacuum extraction.

RESULTS

Episiotomy was associated with a reduction in OASIS from 15.5% to 11.8%, average treatment effect of -3.66% (95% CI -4.31 to -3.01) and NNT 27. Third-degree perineal injuries were reduced from 14.0% to 10.9% (-3.08, 95% CI -3.71 to -2.42) with NNT 32. Fourth-degree perineal injuries were reduced from 1.6% to 1.0 % (-0.58%, 95% CI -0.79 to -0.37) with NNT 172.

CONCLUSIONS

Lateral or mediolateral episiotomy reduced the prevalence of OASIS in nulliparous women delivered with vacuum extraction, compared to women with no episiotomy.

TWEETABLE ABSTRACT

To prevent one case of OASIS in first-time mothers delivered with vacuum, 27 episiotomies had to be performed.

Obstetric anal sphicnter injury in a Spanish hospital

OBJECTIVE

Estimation of the prevalence of obstetric anal sphincter injury (OASIS) in our environment and study of the associated risk factors.

STUDY DESING

A retrospective observational study of cases and controls of assisted deliveries at the Severo Ochoa University Hospital of Leganés during the period from January 1, 2012, to December 31, 2017. A total of 88 OASIS diagnosed in the study period is compared with a randomly selected group of 181 controls of similar characteristics, vaginal births of cephalic of 36 weeks gestation or more, occurring during the same period.

RESULTS

During the study period, a total of 8160 deliveries were attended in our hospital, of which 6187 were vaginal and we diagnosed a total of 88 OASIS at the time of delivery. The prevalence of OASIS is 1.07 % for total births and 1.42 % for total vaginal deliveries. In the case-control study, the univariate analysis shows statistical significance for nulliparity (OR 3.84; 95 % CI 2.155-6.834; p < 0.001), instrumental delivery (OR 8.73; 95 % CI 4.706-16.2016; p < 0.001), occipital posterior position (OR 7.23; 95 % CI 2.535-20.633; p < 0.001), long duration of the second stage of labor (OR 1.99; IC95 % 1,159-3,438; p 0.01), episiotomy (OR 3.51; 95 % CI 1,956-6,309; p < 0.001) and OBGYN labor assistant (<0.001). When performing the multivariate analysis, forceps delivery (OR19.68), Thierry spatulas delivery (OR 8.15), vacuum delivery (OR 2.74), nulliparity (OR 2.56) and fetal weight in grams (OR 1.12) remain significant in the final model.

CONCLUSION

The main risk factors for the onset of OASIS are instrumental delivery, nulliparity and fetal birth weight.

Complications of operative vaginal delivery and provider volume and experience

Objective: To evaluate associations between operative vaginal delivery complications and provider experience (operative vaginal delivery volume and time since residency).Methods: We included all operative vaginal deliveries between 2008 and 2014 at a tertiary care teaching hospital, stratified into forceps-assisted and vacuum-assisted deliveries. Complications included severe perineal lacerations (3rd and 4th degree) and neonatal injuries (subgaleal/subdural/cerebral hemorrhage, facial nerve injury, and scalp injury), which were identified by International Classification Diagnosis-9 codes. Providers were categorized by operative vaginal delivery volume (mean annual forceps- or vacuum-assisted deliveries over the study interval) and time since residency. Regression analyses were used to compare complication rates by provider volume and time since residency, adjusting for potential confounders, using 0-1 deliveries per year and <5 years since residency as reference groups.Results: Nine hundred and thirty-four forceps and 1074 vacuums occurred. For forceps-assisted deliveries, severe perineal injury was decreased among providers with >10 forceps per year (aOR 0.50 [95%CI 0.30-0.81]) and at 15-19 years (aOR 0.45 [95% CI 0.22-0.94], and ≥25 years (aOR 0.45 [0.27-0.73]) since residency. There were no associations with neonatal injuries. Among vacuum-assisted deliveries, severe perineal injury decreased at ≥25 years since residency (aOR 0.35 [95%CI 0.17-0.74], with no association with provider volume. Neonatal injury decreased at 5-9 years (aOR 0.53 [95%CI 0.30-0.93]), and 15-19 years since residency (aOR 0.53 [95%CI 0.29-0.97]), due to differences in scalp injuries. Neonatal injuries other than scalp injury were rare.Conclusion: Severe perineal lacerations decreased with increasing operative vaginal delivery experience, primarily among forceps-assisted vaginal delivery. Providers >5 years since residency may have lower scalp injury with vacuums, but this cohort was largely underpowered for neonatal injury.