Rate Of Obstetric Anal Sphincter Injuries Research Articles

The association between BMI, episiotomy, and obstetric anal sphincter injuries (OASIS) in singleton vaginal deliveries

ObjectivePrevalence of obesity in reproductive age and pregnant women has been on the rise during the past several decades. The relationship between body mass index (BMI) and obstetric anal sphincter injuries (OASIS) or episiotomy has not yet been thoroughly investigated. The objective of this study was to shed light on this issue. MethodsThis retrospective cohort study was performed using electronic database of an obstetrics department at a university-affiliated tertiary medical center. All spontaneous singleton vaginal deliveries at term between January 2015 and December 2021 were included. The primary outcome was the incidence of OASIS (third- and fourth-degree perineal tears) and obesity. These were compared across three BMI categories: normal (BMI below 25 kg/m2), overweight (BMI 25.0–29.9 kg/m2), and obesity (BMI of 30 kg/m2 and over). ResultsOf the overall 13,932 spontaneous vaginal deliveries identified, 34.7 % had BMI in the normal range, 43.1 % were overweight, and 25.4 % were obese. Multivariate analysis demonstrated lower rates of OASIS in obese (OR 0.2, 95 %CI 0.04–0.9) and in overweight (OR 0.3, 95 %CI 0.1–0.99) women, as compared to the normal-weight cohort. In addition, lower rates of episiotomy were noted in the obese cohort (OR 0.7, 95 %CI 0.6–0.8). ConclusionsDecreased incidence of OASIS was noted in women with obesity, in conjunction with lower use of episiotomy. These findings imply that obstetrics clinics might consider a more conservative approach to episiotomy in obese patients.

Is vaginal birth after cesarean section a risk factor for obstetric anal sphincter injury?

To investigate whether women undergoing their first vaginal delivery after a previous cesarean section (secundiparous) are at increased risk for obstetric anal sphincter injury (OASI) compared with primiparous women. A retrospective cohort study of 85 428 women who delivered vaginally over a 10-year period in a single tertiary medical center. Incidence of OASI, risk factors, and clinical characteristics were compared between primiparous women who delivered vaginally and secundiparous women who underwent their first vaginal birth after cesarean section (VBAC). A multivariable logistic regression analysis was used to study the association between VBAC and OASI. Overall, 36 250 primiparous and 1602 secundiparous women were enrolled, 309 of whom had OASI. The rates of OASI were similar among secundiparous women who had VBAC and primiparous women who underwent vaginal delivery (15 [0.94%] vs 294 [0.81%], P = 0.58). The proportions of third- and fourth-degree tears were also similar among secundiparous and primiparous women who experienced OASI (87% vs 91.5%, and 13% vs 8.5%, respectively, P = 0.68). Furthermore, the rates of OASI were similar in both study groups, although secundiparous women who underwent VBAC had higher rates of birth weights exceeding 3500 g (414 [25.8%] vs 8284 [22.8%], P = 0.016), and higher rates of vacuum-assisted deliveries (338 [21%] vs 6224 [17.2%], P < 0.001). A multivariate logistic regression analysis failed to establish a statistically significant association between VBAC and OASI (odds ratio 0.672, 95% confidence interval 0.281-1.61, P = 0.37). No increased risk for OASI was found in secundiparous women who underwent VBAC compared with primiparous women at their first vaginal birth.

Risk of Obstetric Anal Sphincter Injury by Delivering Provider

Introduction and Hypothesis: Obstetric anal sphincter injuries (OASIs) complicate 5.8% of vaginal deliveries. Our objective was to assess if the primary delivery provider, a nurse-midwife versus physician obstetrician, is associated with OASIs. Methods: We performed a secondary analysis of the Consortium of Safe Labor, a multicenter, retrospective cohort study. Included were nulliparous women with singleton, vaginal delivery at ≥37 weeks from 2002 to 2008. Women were excluded if delivery was complicated by shoulder dystocia or from sites without midwife deliveries. Student’s t-tests, chi-squared analysis, and Fisher’s exact test were used as appropriate. Multivariable logistic regression and propensity score-matching analyses were performed. Results: Of 228,668 births at 19 sites, 2735 births from 3 sites met the inclusion criteria: 1551 physician and 1184 midwife births. Of all births, 4.2% (n = 116) were complicated by OASIs. Physician patients were older, more often White, privately insured, with higher BMI, more medical co-morbidities, and labor inductions/augmentations. Midwife patients had higher fetal gestational age and infant birth weights (all p &lt; 0.05). OASIs were more common in physician compared to midwife births (5.9% vs. 2.0%, p &lt; 0.0001). This difference persisted in multivariable logistic regression. OASIs were 2.4 (95%CI 1.5–3.9) times more likely with physician delivery when controlling for maternal heart disease, episiotomy, increasing maternal age, decreasing maternal BMI, non-White race, and increasing birthweight. The AUC was 0.78. With propensity score matching, OASI rates remained higher amongst physician births (6.6% vs. 1.8%, p &lt; 0.0001; aOR 3.8 (95%CI 2.0–7.1)). Conclusion: OASIs were more common in physician compared to midwife deliveries even when controlling for other associated factors.

Variation in Episiotomy Use Among Nulliparous Individuals by Maternity Care Provider and Associated Rates of Obstetric Anal Sphincter Injury

ObjectivesTo quantify variation in the association between episiotomy and obstetric anal sphincter injury (OASI) by maternity care provider in spontaneous and operative vaginal deliveries (SVDs and OVDs). MethodsPopulation-based retrospective cohort study of vaginal, term deliveries among nullipara in Canada (2004–2015). Adjusted rate ratios (ARRs) and 95% CIs were estimated using log-binomial regression to quantify the associations between episiotomy and OASI, stratified by care provider (obstetrician [OB], family physician [FP], or registered midwife [RM]) while adjusting for potential confounders. ResultsThe study included 631 642 deliveries. Episiotomy use varied by provider: among SVDs, the episiotomy rate was 19.6%, 14.4%, and 8.4% in the OB, FP, and RM groups, respectively. The rate of OASI was higher among SVDs with versus without episiotomy (5.8% vs 4.6%). Conversely, OASI occurred less frequently in operative vaginal deliveries with episiotomy (15.3%) compared with those without (16.7%). In all provider groups, the ARR for OASI was increased with episiotomy in SVD and decreased with episiotomy with forceps delivery. No differences in these associations were observed by provider except among vacuum delivery (ARR with episiotomy vs. without, OB: 0.88, 95% CI 0.84–0.92; FP: 0.89, 95% CI 0.83–0.96, RM: 1.22, 95% CI 1.02–1.48). ConclusionsIn nullipara, irrespective of maternity care provider, there is a positive association between episiotomy and OASI among SVDs and an inverse association between episiotomy and deliveries with forceps. The relationship between episiotomy and OASI is modified by maternity care providers among vacuum deliveries.

Maternal origin matters: Country of birth as a risk factor for obstetric anal sphincter injuries.

Obstetric anal sphincter injuries (OASIS) are severe complications to vaginal births with potential long-term consequences. Maternal origin has been proposed to affect the overall risk, but the association and underlying explanation are uncertain. The objective was to assess the association between maternal country of birth and OASIS. A Swedish nationwide cohort study including singleton term vaginal births during 2005-2016. Data were extracted from the Swedish Medical Birth Registry and Statistics Sweden. Modified Poisson regression analyses were performed to obtain crude and adjusted risk ratios (RRs). Adjustments were made in four cumulative steps. Sub-analyses were performed to investigate the risk of OASIS associated with female genital circumcision (FGC). In all, 988 804 births were included. The rate of OASIS in Swedish-born women was 3.5%. Women from East/Southeast Asia had an increased risk of OASIS (adjusted RR [aRR] 1.71, 95% confidence interval [CI] 1.60-1.83), as did women born in Sub-Saharan Africa (aRR 1.60, 95% CI 1.49-1.72). The risk remained significantly increased also after adjustment for maternal height. By contrast, women from South/Central America had a decreased risk of OASIS (aRR 0.65, 95% CI 0.56-0.76). FGC was associated with an increased risk of OASIS (aRR 3.05, 95% CI 2.60-3.58). Episiotomy appeared to have an overall protective effect (aRR 0.95, 95% CI 0.92-0.98), but not significantly more protective among women with female genital mutilation. Country of birth plays an important role in the risk of OASIS. Women from East/Southeast Asia and Sub-Saharan Africa are at significantly increased risk as compared with Swedish-born women, whereas women from South/Central America are at lower risk. FGC is also a significant risk factor for OASIS.

Asian-white disparities in obstetric anal sphincter injury: Protocol for a systematic review and meta-analysis.

Obstetric anal sphincter injury (OASI) describes severe injury to the perineum and perineum and perianal muscles following birth and occurs in 4.4% to 6.0% of vaginal births in Canada. Studies from high-income countries have identified an increased risk of OASI in individuals who identify as Asian race versus those who identify as white. This protocol outlines a systematic review and meta-analysis which aims to determine the incidence of OASI in individuals living in high-income countries who identify as Asian versus those of white race/ethnicity. We hypothesize that the pooled incidence of OASI will be higher in Asian versus white birthing individuals. We will search MEDLINE, OVID, Embase, Emcare and Cochrane databases from inception to 2022 for observational studies using keywords and controlled vocabulary terms related to race, ethnicity and OASI. Two reviewers will follow the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines and Meta-analysis of Observational Studies (MOOSE) recommendations. Meta-analysis will be performed using RevMan for dichotomous data using the random effects model and the odds ratio (OR) as effect measure with a 95% confidence interval (CI). Subgroup analysis will be performed based on Asian subgroups (e.g., South Asian, Filipino, Chinese, Japanese individuals). Study quality assessment will be performed using The Joanna Briggs Institute Critical Appraisal tools. The systematic review and meta-analysis that this protocol outlines will synthesize the extant literature to better estimate the rates of OASI in Asian and white populations in non-Asian, high-income settings and the relative risk of OASI between these two groups. This systematic summary of the evidence will inform the discrepancy in health outcomes experienced by Asian and white birthing individuals. If these findings suggest a disproportionate burden among Asians, they will be used to advocate for future studies to explore the causal mechanisms underlying this relationship, such as differential care provision, barriers to accessing care, and social and institutional racism. Ultimately, the findings of this review can be used to frame obstetric care guidelines and inform healthcare practices to ensure care that is equitable and accessible to diverse populations.

Is an episiotomy always necessary during an operative vaginal delivery with vacuum? A longitudinal study

Objective: The use of episiotomy during operative vaginal birth (OVB) is rather debated among operators and in literature. It is also important to evaluate the indications for which episiotomy is performed. In fact, the consequences of an episiotomy can be invalidating for patients with long-lasting results. The aim of this study is the evaluation of the role of episiotomy during OVB with the vacuum extractor and its correlation with Obstetric Anal Sphincter Injuries (OASIs). Methods: On of 9165 vaginal births, a total of 498 OVB (5.4%) were enrolled in a longitudinal prospective observational study. The incidence of OASIs was evaluated in our population after OVB performed with the vacuum extractor, during which the execution of episiotomy was performed indicated by clinician in charge. Results: OASIs occurred in 4% of the patients (n = 20). Episiotomy was performed in 39% of them (n = 181). OASIs incidence was 6% (n = 17) in the No Episiotomy and 1.8% (n = 3) in Episiotomy group (p<.001). Performance of episiotomy during OVB determined a protective effect against OASIs (p = 0.025 in full cohort and p = 0.013 in the primiparous group). An expulsive phase under one hour was an almost significant protective factor (p = 0.052). Conclusions: The use of episiotomy during OVB was associated with much lower OASIs rates in nulliparous women with a vacuum extraction; OR 0.23 (CI 95% 0.07-0.81) p = 0.037 in nulliparous women and the number necessary to treat was 18 among nulliparous women to prevent 1 OASIs. A further risk factor that emerged from the analysis is a prolonged expulsive period, whereas fundal pressure does not seem to have a statistically significant influence.

Risk indicators for obstetrical anal sphincter injury in vaginal birth after caesarean section compared to first vaginal delivery

ObjectivesComparison of the rate of obstetric anal sphincter injury (OASI) between women having their first vaginal birth after caesarean section (CS) and true nulliparous women with a vaginal delivery. Assessment of risk indicators for OASI in women with vaginal birth after one CS (VBAC). Study design28 535 women with their first VBAC and a cohort of 275 439 nulliparous women with a vaginal delivery of a liveborn infant in a cephalic position from the Dutch perinatal registry were analyzed. We compared the OASI rate with univariate and multivariate analysis. In women with VBAC possible risk indicators for OASI were assessed using univariate and multivariate logistic regression analysis. ResultsThe rate of OASI was 5.2% in women with vaginal birth after CS and 4.0% in women with a first vaginal delivery. The adjusted OR (aOR) for vaginal birth after an elective CS was higher (aOR 1.34, 95% CI 1.23–1.47) compared to vaginal birth after an emergency CS (aOR 1.16, 95% CI 1.08–1.25). In women with vaginal birth after emergency CS, the aOR for the indication non-progressive labor was 1.18 (95% CI 1.08–1.29), whereas CS for suspected fetal distress was not significantly associated with obstetric anal sphincter injury in VBAC.In the 28 535 women with a VBAC, mediolateral episiotomy (MLE), birth weight < 3000 g and maternal age < 25 years were associated with a significantly lower rate of OASI. A gestational age of 42 weeks, birth weight ≥ 3500 g, operative vaginal delivery and duration of the 2nd stage of labour of ≥ 60 min were associated with a significantly higher rate of OASI. ConclusionsWomen with a VBAC have a higher rate of OASI in comparison with women with a first vaginal delivery, with the exception of women with a vaginal birth after an emergency CS for suspected fetal distress. Factors associated with a significantly lower rate for OASI were MLE, maternal age < 25 and birth weight < 3000 g. A gestational age of 42 weeks, birth weight between 3500 and 4000 g and ≥ 4000 g, operative vaginal delivery and duration of the 2nd stage of delivery longer dan 60 min were associated with a significantly higher rate of OASI.

Implementation of Episcissors-60 for Prevention of Obstetric Anal Sphincter Injuries (OASIS) in a Centre with Low Episiotomy Rates

ObjectifCette étude avait pour objectif de déterminer si l’adoption des ciseaux Episcissors-60 à l’unité des naissances diminuerait la fréquence des lésions obstétricales du sphincter anal (LOSA). MéthodeUne étude sur l’amélioration de la qualité pré- et post-intervention a été menée pour la période du 1er avril 2020 au 31 mars 2021. Toutes les patientes ayant accouché par voie vaginale ont été incluses dans cette étude. Tous les fournisseurs de soins qui réalisent des accouchements vaginaux se sont fait offrir une séance de formation. Les ciseaux Episcissors-60 ont été ajoutés aux instruments disponibles à l’unité des naissances. Le critère de jugement principal était le changement de la fréquence des LOSA avant et après l’adoption des ciseaux Episcissors-60. Les critères de jugement secondaires étaient le taux d’épisiotomie avant et après l’adoption de ces ciseaux, le taux d’événements indésirables liés à l’instrument ainsi que le taux de satisfaction et les commentaires des fournisseurs de soins. Les données ont été analysées à l’aide de tests du chi carré, de tests t indépendants et de tests de Mann-Whitney. RésultatsAu total, dans la période à l’étude, il y a eu 1383 accouchements vaginaux avant et 1254 accouchements vaginaux après l’adoption des ciseaux Episcissors-60. Il y a eu une diminution du taux total de LOSA, lequel est passé de 7.37 % à 5.37 % de tous les accouchements vaginaux après l’adoption des ciseaux Episcissors-60 (P = 0,037). Le taux d’épisiotomie était de 11.42 % avant et de 9.97 % après l’adoption des ciseaux Episcissors-60 (P = 0.228). Le taux de LOSA chez les femmes ayant subi une épisiotomie était de 12.02 % avant et de 13.60 % après l’adoption des ciseaux Episcissors-60 (P = 0.421). ConclusionBien que l’adoption des ciseaux Episcissors-60 ait été associée à une diminution statistiquement significative du taux total de LOSA, il n’y avait aucune différence du taux de LOSA dans le sous-groupe d’épisiotomie. Par conséquent, la réduction du taux total de LOSA dans cette étude ne peut pas être attribuée à l’utilisation des ciseaux Episcissors-60.

High Incidence of Obstetric Anal Sphincter Injuries among Immigrant Women of Asian Ethnicity.

(1) Background: Obstetric anal sphincter injuries (OASI) may complicate vaginal deliveries. The aim of the present study was to explore the incidence and clinical characteristics of OASI among Asian women living in a Western country compared to local Caucasian women. (2) Methods: A retrospective cohort study of 380 women diagnosed with OASI, following singleton vaginal deliveries, during a 10-year period (January 2011 to December 2020). Exclusion criteria: age < 18 years, stillbirth, and breech presentation. Demographic, clinical, and obstetrical data were obtained, and a comparison between Asian and Caucasian women was performed. (3) Results: There were 35 cases of OASI among 997 women of Asian ethnicity compared to 345 cases of OASI among 86,250 Caucasian women (3.5% vs. 0.4%, respectively, p < 0.001). Asian women endured a significantly higher rate of fourth-degree OASI (17.1%) even though they bore smaller newborns (3318 g vs. 3501 g, p = 0.004), and birth weights rarely exceeded 3800 g (2.8% vs. 25.8%, p < 0.001). Asian ethnicity was also associated with a significantly higher risk for blood transfusion following OASI and a lower tendency for postpartum follow up. (4) Conclusions: Immigrant women of Asian ethnicity had a nine-fold higher rate of OASI, much higher than previously reported. Furthermore, Asian women had higher rates of fourth-degree OASI.

Risk of obstetric anal sphincter tear among primiparous women with a history of female genital mutilation, giving birth in Sweden.

Female genital mutilation (FGM) includes a range of procedures involving partial or total removal of the external female genitalia. It is a harmful procedure that violates human rights of girls and women. FGM has been associated with obstetric anal sphincter injury (OASI), among other adverse obstetric complications. However, the obstetric outcomes in high-income countries are not clear. The aim of this study was to compare the risk of OASI among primiparous women, with and without a history of FGM, giving birth in Sweden. A population-based cohort-study based on data from the Swedish Medical Birth Register during the period 2014-2018. The study included primiparous women with singleton term pregnancies. We compared the risk, using multivariable logistic regression, of our main outcome OASI between women with a diagnosis of FGM and women without a diagnosis of FGM. Secondary outcomes included episiotomy and instrumental vaginal delivery. A total of 239,486 primiparous women with a term singleton pregnancy were identified. We included 1,444 women with a diagnosis of FGM and 186,294 women without a diagnosis of FGM in our analysis. The overall rate of OASI was 3% in our study population. By using multivariable logistic regression analysis, we found that women with a diagnosis of FGM had a significantly increased odds ratio (OR) of OASI (OR 2.69, 95%CI: 2.14-3.37) compared to women without a diagnosis of FGM. We also found an association between FGM and instrumental delivery as well as the use of episiotomy. Women with a history of FGM have an almost tripled risk of OASI in comparison with women without FGM, when giving birth in a Swedish setting. Increased knowledge and awareness regarding FGM, and its potential health implications is crucial in order to minimise the risk of OASI among women with FGM giving birth in high-income countries. A limitation in our study is the lack of information about the specific types of FGM.

Impact of fetal manipulation on maternal and neonatal severe morbidity during shoulder dystocia management.

There are few data on maternal and neonatal morbidities associated with shoulder dystocia (SD), depending on the use of fetal manipulation (FM). A prior 5-year study was conducted in our center in 2012 for this purpose. Our objective was to compare severe maternal and neonatal morbidities according to FM execution in a larger cohort. We conducted a retrospective study between 2007 and 2020. SD was considered when additional maneuvers were required to complete a delivery. Severe maternal morbidity was defined as the occurrence of obstetric anal sphincter injury (OASI). Severe neonatal morbidity was defined as Apgar < 7 at 5min and/or cord arterial pH < 7.1 and/or or a permanent brachial plexus palsy. We studied these data in the FM group compared to the non- FM group. FM was associated with increased OASI rates (21.1% vs. 3.8%, OR = 6.72 [2.7-15.8]). We found no significant difference in severe neonatal morbidity. Maternal age > 35 and FM appear to be associated with the occurrence of OASI, with ORa = 13.3 [1.5-121.8] and ORa = 5.3 [2.2-12.8], respectively. FM was the only factor associated with the occurrence of severe neonatal morbidity (ORa = 2.3 [1.1-4.8]. The rate of episiotomy was significantly decreased (20% versus 5% p < 0.05) and there was an increase in the rate of SD managed with FM in our center. FM is the only factor associated with an increased risk of OASI. In case of failure of non-FM maneuvers, the rapid implementation of FM maneuvers resulted in no difference regarding severe neonatal morbidity.

Can transperineal ultrasound improve the diagnosis of obstetric anal sphincter injuries?

Women with missed obstetric anal sphincter injuries (OASIs) are at an increased risk of anal incontinence. Our aim was to assess the accuracy of three-dimensional (3D) transperineal ultrasound (TPUS) compared with clinical examination for detecting OASIs. A cross-sectional study of women undergoing their first vaginal delivery. Perineal trauma was initially assessed by the doctor or midwife performing the delivery (accoucheur) and women were then re-examined by the trained research fellow (KW). A 3D TPUS was performed immediately after delivery before suturing to identify OASIs. The research fellow's clinical diagnosis was used as the reference standard. A power calculation determined that 216 women would be required for the study. Two hundred and sixty-four women participated and 226 (86%) delivered vaginally. Twenty-one (9%) sustained OASIs. Six (29%) of these tears were missed by the accoucheur but were identified by the research fellow. TPUS identified 19 of the 21 (90.5%) OASIs. One percent (n = 2) had sonographic appearances of an anal sphincter defect that was not seen clinically. The positive and negative predictive value of TPUS to detect OASIs was 91% and 99% respectively. TPUS identified 91% of OASIs compared with 71% detected by the accoucheur, which was not statistically significant. The detection rate of OASIs with TPUS and with the clinical findings of the accoucheur was similar. Given the training and financial implications needed for TPUS, attention needs to be focused on the training of midwives and doctors to identify anal sphincter injuries by clinical examination.

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

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. 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. 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. 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. 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.

Mode of delivery following obstetric anal sphincter injury: a 7-year retrospective review and follow-up cohort survey.

Limited evidence exists regarding long-term outcomes following birth after prior obstetric anal sphincter injury (OASI). This article set out to describe outcomes following birth after OASI by reviewing the grades of tear, endoanal ultrasound (EAUS) findings, subsequent delivery outcomes and long-term symptoms. This study was conducted in two parts. The first involved a retrospective review of all OASI at a tertiary hospital in Australia over 7 years (2013-2019 inclusive) where the patient underwent a subsequent delivery. Following this, a retrospective cohort survey of this group was performed. There were 27,284 vaginal births and 828 OASIs (3.03%); 247 (29.8%) had at least one subsequent birth by January 2021. Vaginal delivery occurred in 68%; recurrence of OASI was 5.4%. There were 90 responses (36.4%) to the follow-up survey. EAUS had been performed in 87.5%; none demonstrated a defect. Vaginal birth was the preferred mode for 77.8%; this occurred in 64%. The majority had high levels of satisfaction, this related to communication rather than the mode of delivery itself. Ongoing faecal or flatal incontinence was reported by 12%. There was no statistically significant difference in St Mark's incontinence scores between modes of birth. In our unit most women who sustain OASI will have a subsequent vaginal delivery in future pregnancies. The majority remain asymptomatic at long-term follow-up with no statistically significant difference in incontinence scores regardless of mode of delivery. The rate of recurrent OASI was 5.4%.

French guidelines for restrictive episiotomy during instrumental delivery were not followed by an increase in obstetric anal sphincter injury

The objective was to assess the influence of the French guidelines in favor of a restrictive use of episiotomy on both episiotomy and obstetric anal sphincter injury (OASI) rates during instrumental delivery. It was aulticenter study involving 193 maternities between 2000 and 2016. We included women with a singleton pregnancy, with cephalic presentation at 34 weeks of gestation or more who underwent an instrumental delivery. The study period was divided into three phases: 2000–2005 (reference) 2006–2011, and 2012–2016. We calculated the adjusted relative risk (aRR) of episiotomy and OASI and investigated for changes in episiotomy and OASI rates over time by using Prais–Winsten regression. We considered 96,035 deliveries. The episiotomy’s risk was lower in 2006–2011 (69.4%) and 2012–2016 (59.1%) compared to 2000–2005 (81.2%), respectively: aRR 0.93 [0.92–0.95] and 0.89 [0.87–0.90]. The OASI’s risk was higher in 2006–2011 (2.5%) and 2012–2016 (3.1%) compared to 2000–2005, respectively: aRR 1.30 [1.10–1.53]) and 1.57 [1.33–1.85]. However, Prais–Winsten regression showed no difference in the OASI rate during the study period. We observed a massive decrease in episiotomy use and a moderate increase in crude OASI’s rate but multivariate analysis failed to report an association between these outcomes.

Obstetric Anal Sphincter Injuries (OASIS) in Multiparous Women With the Use of Epidural Anaesthesia: A Retrospective Cohort Study

(Aust N Z J Obstet Gynaecol. 2021;61:30–34) Epidural anesthesia is the gold standard for managing labor pain. But it is also associated with longer second stage of labor and an increased risk of instrumental vaginal delivery, which can lead to obstetric anal sphincter injuries (OASIS). The risk of OASIS is 5.7% in women giving birth for the first time, compared with 1.5% in multiparous women with no history of OASIS. The aim of this study was to evaluate the impact of epidural use in multiparous women on the rates of OASIS and other outcomes.

Which elements were significant in reducing obstetric anal sphincter injury? A prospective follow-up study

BackgroundTo examine which elements of an obstetric anal sphincter injury (OASI) care bundle were protective for OASI. Several interventional trials showed that application of a care bundle involving a hands-on approach to perineal protection may reduce the risk of OASI. Previously, we found that only the element “hand on the fetal head” in itself was protective, although the risk of a type 2 error was calculated to be 50%.MethodsA prospective follow-up study in an obstetric department in Denmark with 3200 deliveries per year. We included a cohort of 10,383 women giving birth vaginally from gestational week 22 + 0 from 2016 through 2019. We documented on a person-level the five elements of the care bundle together with maternal and obstetrical characteristics. The elements were 1) communication, 2) visible perineum, 3) hand on fetal head, 4) perineal support and 5) certification. Regression analysis was used for analysis of associations. The primary outcome measure was OASI.ResultsThe total rate of OASI in vaginally delivering women was 1.9%. The incidence was 3.2% in nulliparous women giving birth vaginally. The rate of cesarean section was 16.5% and for episiotomy 2.4%. The reduction in the incidence of OASI was sustained since 2013. Hand on the fetal head and perineal support both were protective factors for OASI. In case of a nulliparous woman with a neonate weighing 3500 g giving birth spontaneously, the relative risk (RR) for OASI was 0.50 (95% CI 0.49- 0.51) with use of hand on the fetal head together with perineal support against no use. Similarly, with a nulliparous woman giving birth to a neonate of 3500 g by vacuum extraction, the RR for OASI was 0.65 (95% CI 0.62-0.68) against no use.ConclusionsBoth hand on the fetal head and perineal support were associated with a reduced risk of OASI.

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

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). Aggregated data on 1933930 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. 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. 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.

OASI2: a cluster randomised hybrid evaluation of strategies for sustainable implementation of the Obstetric Anal Sphincter Injury Care Bundle in maternity units in Great Britain.

BackgroundThe Obstetric Anal Sphincter Injury (OASI) Care Bundle comprises four primary and secondary prevention practices that target the rising rates of severe perineal tearing during childbirth, which can have severe debilitating consequences for women. The OASI Care Bundle was implemented in 16 maternity units in Britain in the OASI1 project (2017-2018), which demonstrated the care bundle’s effectiveness in reducing OASI rates. In OASI2, the care bundle will be scaled up to 20 additional National Health Service (NHS) maternity units in a hybrid effectiveness-implementation study that will examine the effectiveness of strategies used to introduce, implement and sustain the care bundle.MethodsOASI2 is a two-arm cluster-randomised control trial (C-RCT) of maternity units in England, Scotland and Wales, with an additional non-randomised study arm. C-RCT arm 1 (peer support, n = 10 units) will be supported by ‘buddy’ units to implement the OASI Care Bundle. C-RCT arm 2 (lean implementation, n = 10 units) will implement without external support. The additional study arm (sustainability, n = 10 units) will include some original OASI1 units to evaluate the care bundle’s sustainability and OASI rates over time, from before OASI1 and through the end of OASI2. Units in all three study arms will receive an Implementation Toolkit with training resources and implementation support. The C-RCT arms will be compared in terms of OASI rate reduction (primary effectiveness outcome) and clinicians’ adoption of the care bundle (primary implementation outcome). Clinical data will be collated from maternity information systems; implementation data will be collected through validated surveys with women and clinicians, supplemented by qualitative methods. Descriptive statistics and regression modelling will be used for analysis. Emergent themes from the qualitative data will be assessed using framework analysis.DiscussionOASI2 will study the impact of various implementation strategies used to introduce and sustain the OASI Care Bundle, and how these strategies affect the bundle’s clinical effectiveness. The study will generate insights into how to effectively scale-up and sustain uptake and coverage of similar interventions in maternity units. A locally adaptable ‘implementation blueprint’ will be produced to inform development of future guidelines to prevent perineal trauma.Trial registrationISRCTN26523605