Risk factors for obstetric anal sphincter injury among parous women

Guideline No. 457: Obstetrical Anal Sphincter Injuries (OASIS) Part I: Prevention, Recognition, and Immediate Management

OBJECTIVE

The purpose of this guideline is to promote recognition and preventive strategies for obstetrical anal sphincter injuries. Furthermore, it provides guidance on primary repair and immediate postpartum management for obstetrical anal sphincter tears in order to minimize further negative sequelae.

TARGET POPULATION

All patients having a vaginal delivery and those who have sustained an obstetrical anal sphincter injury.

OUTCOMES

Certain preventive strategies have been associated with lower rates of obstetrical anal sphincter injuries (e.g., fetal head flexion and control, appropriate use of mediolateral episiotomy). Management strategies, including appropriate diagnosis and repair of obstetrical anal sphincter injuries, antibiotic prophylaxis, and bowel and bladder function management can decrease associated short- and long-term complications.

BENEFITS, HARMS, AND COSTS

Implementation of the recommendations in this guideline may increase detection, prevention, and appropriate management of obstetrical anal injuries, thus limiting the future burden associated with these injuries. Implementation of the recommended classification of obstetrical anal sphincter injuries will improve national and international research efforts.

EVIDENCE

Published literature was retrieved through searches of PubMed, Ovid, Medline, Embase, Scopus, and the Cochrane Library from September 1, 2014, through November 30, 2023, using appropriate MeSH terms (delivery, obstetrics, obstetric surgical procedures, obstetric labor complications, anal canal, episiotomy) and keywords (OASIS, obstetrical anal sphincter injury, anal injury, anal sphincter, vaginal delivery, suture, fecal incontinence, anal incontinence, overlap repair, end-to-end repair, bladder protocol, analgesia). Results were restricted to systematic reviews, meta-analyses, randomized controlled trials/controlled clinical trials, observational studies, and clinical practice guidelines. Results were limited to English- or French-language materials. Evidence was supplemented with references from the 2015 Society of Obstetricians and Gynaecologists of Canada guideline no. 330.

VALIDATION METHODS

The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix A (Tables A1 for definitions and A2 for interpretations of strong and conditional recommendations).

INTENDED AUDIENCE

Obstetrical care providers.

TWEETABLE ABSTRACT

Updated Canadian guideline on recognition, prevention and management of obstetrical anal sphincter injuries (OASIS).

SUMMARY STATEMENTS

RECOMMENDATIONS.

Prevalence and associated factors of maternal birth trauma following vaginal delivery at University of Gondar Comprehensive Specialized Hospital, North-West Ethiopia, 2022

BACKGROUND

Maternal injury with any form of perineal trauma following vaginal delivery is very common which ranges globally from 16.2 to 90.4%. The frequency of Obstetric anal sphincter Injuries and the incidence of cervical laceration increases rapidly. However, in Ethiopia, there is limited evidence on the prevalence of maternal birth trauma and its determinant factors after vaginal delivery.

OBJECTIVE

To assess the magnitude and associated factors of Maternal Birth Trauma after vaginal delivery at University of Gondar Comprehensive Specialized Hospital, Gondar, North-West Ethiopia, 2022.

METHODS

An Institution based cross-sectional study was conducted among mothers with singleton vaginal delivery at University of Gondar Comprehensive Specialized Hospital from 9th May to 9th August 2022 among 424 study participants. Pre-tested semi-structured questioner was utilized. Epi-Data version 4.6 was used for data entry and exported to SPSS version 25 for data management and analysis. To identify the determinant factors, binary logistic regression model was fitted and variables with p-value < 0.2 were considered for the multivariable binary logistic regression analysis. In the multivariable binary logistic regression analysis, Variables with P-value < 0.05 were considered to have statistical significant association with the outcome variable. The Adjusted Odds Ratio (AOR) with 95% CI was reported to declare the statistical significance and strength of association between Maternal Birth Trauma and independent variables.

RESULTS

A total of 424 mothers who delivered vaginally were included. The mean age of participants was 26.83 years (± 5.220 years). The proportion of birth trauma among mothers after vaginal delivery was47.4% (95%CI: 43.1, 51.7). Of different forms of perineal trauma, First degree tear in 42.8%, OASIs in 1.5% and Cervical laceration in 2.5% study participants. In the multivariable binary logistic regression analysis being primiparous (AOR = 3.00; 95%CI: 1.68, 5.38), Gestational age ≥ 39 weeks at delivery (AOR = 2.96; 95%CI: 1.57, 5.57), heavier birth weight (AOR = 12.3; 95%CI: 7.21, 40.1), bigger head circumference (AOR = 5.45; 95%CI: 2.62, 11.31), operative vaginal delivery (AOR = 6.59; 95%CI: 1.44, 30.03) and delivery without perineum and/or fetal head support (AOR = 6.30; 95%CI: 2.21, 17.94) were significantly associated with the presence of maternal birth trauma.

CONCLUSION AND RECOMMENDATION

Maternal birth trauma following vaginal delivery was relatively high in this study. Prim parity, gestational age beyond 39 weeks at delivery, heavier birth weight, bigger head circumference, operative vaginal delivery and delivery without perineum and/or fetal head supported were factors affecting perineal outcome. The Ministry of Health of Ethiopia should provide regular interventional training as to reduce maternal birth trauma.

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.

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

PURPOSE

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.

METHODS

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 5 min 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.

RESULTS

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.

CONCLUSION

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.

Birthweight difference between deliveries and the risk of obstetric anal sphincter injury in parous women

INTRODUCTION AND HYPOTHESIS

While obstetric anal sphincter injury (OASI) is less frequent in parous compared to nulliparous women, it remains a major concern affecting quality of life of women worldwide. The aim of this study was to evaluate the association between birthweight (BW) difference between deliveries and risk of OASI in parous women.

METHODS

We performed a retrospective case-control study including parous women with at least one previous vaginal delivery who were diagnosed with OASI. The control group consisted of parous women who did not have OASI during vaginal delivery. Controls were matched in a 1:2 ratio by year of birth, maternal age, and parity. Medical history, obstetric background, and current labor-related data were compared. Further univariate and multivariable analyses were performed, assessing for risk factors for OASI.

RESULTS

One hundred eight parous women who had a diagnosis of OASI and a control group of 216 parturients who delivered without OASI were included in the final analysis. Differences between the current BW and the preceding and maximal previous BW were evaluated. There were significantly higher rates of women who had a larger neonate with > 500 g difference between the current and previous BW in the OASI group than in those with no OASI (28.7% vs. 12.30%, respectively; p < 0.001). Following a multivariable analysis for the dependent parameter of OASI, the following parameters were found to be independently associated with OASI outcome: previous operative vaginal delivery, BW ≥ 90th percentile, and current BW ≥ 500 g compared to previous maximal BW.

CONCLUSIONS

In parous women, neonatal BW increase between deliveries of > 500 g is associated with OASI.

Substantial Obstetric Anal Sphincter Injury during Vacuum Assisted Delivery: An Obstetrical Issue or Device Related?

BACKGROUND

Obstetric anal sphincter injuries (OASIS) might be associated with long-term urinary and anorectal morbidities. The aim of the study was to investigate the risk factors and clinical implications of OASIS associated with vacuum-assisted deliveries versus normal vaginal deliveries.

METHODS

A series of 413 consecutive OASIS cases were retrospectively analyzed. A comparison was made between OASIS cases diagnosed following vacuum-assisted deliveries versus OASIS cases diagnosed following normal vaginal deliveries. Multivariable analysis was used to study the association between vacuum-assisted deliveries and superficial (3A and 3B) versus deep (3C and 4) perineal tears.

RESULTS

The study population comprised 88,123 singleton vaginal deliveries. Diagnosis of OASIS was made in 413 women (0.47% of the total cohort), 379 (91.8%) of whom had third-degree tears and 34 (8.2%) of whom had fourth-degree tears. Among the 7410 vacuum-assisted deliveries, 102 (1.37%) had OASIS, whereas, among the 80,713 normal vaginal deliveries, only 311 (0.39%) had OASIS. In a multivariate analysis, only vacuum-assisted delivery was found to be associated with a significant risk of deeper (3C or 4) perineal tears (OR = 1.72; 95% CI 1.02-2.91; p = 0.043).

CONCLUSIONS

Vacuum-assisted instrumental intervention is a significant risk factor for OASIS and especially for deeper tears, independent of other maternal and obstetric risk factors.

Can We Predict Feto-Maternal Adverse Outcomes of Vacuum Extraction?

Introduction Vacuum extraction (VE) is an important modality in modern obstetrics, yet sometimes results in maternal or neonatal adverse outcomes, which can cause a lifetime disability. We aimed to characterize potential risk factors for adverse outcomes that in retrospect would have led the physician to avoid the procedure. Materials and Methods Retrospective cohort of 3331 singleton pregnancies, ≥ 34 w delivered by VE. 263 deliveries (7.9%) incurred a VE-related feto-maternal adverse outcome, defined as one or more of the following: 3-4th-degree perineal laceration, subgaleal hematoma, intracranial hemorrhage, shoulder dystocia, clavicular fracture, Erb's palsy or fracture of humerus. 3068 deliveries (92.1%) did not have VE-related adverse outcomes. Both groups were compared to determine potential risk factors for VE adverse outcomes. Results Multivariable regression found seven independent risk factors for VE-related feto-maternal adverse outcomes: Nulliparity - with an odds ratio (OR) of 1.82 (95% CI = 1.11-2.98, p = 0.018), epidural anesthesia (OR 1.99, CI = 1.42-2.80, p < 0.001), Ventouse-Mityvac (VM) cup (OR 1.86, CI = 1.35-2.54, p < 0.001), prolonged second stage as indication for VE (OR 1.54, CI = 1.11-2.15, p = 0.010), cup detachment (OR 1.66, CI = 1.18-2.34, p = 0.004), increasing procedure duration (OR 1.07 for every additional minute, CI = 1.03-1.11, p < 0.001) and increasing neonatal birthweight (OR 3.42 for every additional kg, CI = 2.33-5.02, p < 0.001). Occiput anterior (OA) position was a protective factor (OR 0.62, CI = 0.43-0.89, p = 0.010). Conclusions VE-related adverse outcomes can be correlated to clinical characteristics, such as nulliparity, epidural anesthesia, VM cup, prolonged second stage as indication for VE, cup detachment, prolonged procedure duration and increasing neonatal weight. OA position was a protective factor. This information may assist medical staff to make an informed decision whether to choose VE or cesarean delivery (CD).

The influence of the fundal pressure manoeuvre at delivery on the anal sphincter injury diagnosed with endoanal ultrasonography

OBJECTIVES

The fundal pressure manoeuvre (FPM) is a procedure where the fundus of the uterus is pushed through the abdominal wall by the midwifes and doctors to shorten the terminal phase of the second stage vaginal delivery. Nowadays its use is controversial and associated with many adverse effects. The aim of the study was to evaluate benefits and adverse maternal outcomes after FPM. The correlation of the FPM with episiotomy was evaluated. The role of the FPM on pelvic floor dysfunction such as anal incontinence due to anal sphincter injury was assessed.

STUDY DESIGN

The retrospective study was conducted between 2017 and 2021. The women who came to the postpartum examination to Gynaecology department for various reasons and gave vaginal birth to a singleton were included in the study. The women who had instrumental delivery were excluded. Minimal sample size was calculated with calculator.net and set on 45. Two groups were formed one with fundal pressure and one without, 96 and 90 patients respectively. The maternal, fetal, and obstetric factors that could be associated with the application of FPM were examined. The endoanal ultrasound examination was performed on all women included in the study.

RESULTS

The study did not show that FPM would lead to a more frequent occurrence of anal sphincter injury (p = 0.73), effect its location (p = 0.77) and depth (p = 0.97), however the test group tended to have longer ruptures compared to control group (p = 0.1). No statistically significant differences in episiotomies between control and test group (p = 0.075) were shown. Endoanal ultrasound showed discrepancy between clinically stated and ultrasonographical diagnoses of anal sphincter injuries. In 61,3% of patients with anal sphincter injury after FPM, reported one of the anal incontinence problems of varying degrees six months after delivery.

CONCLUSION

Given that the study proved that FPM is not correlated to the anal sphincter injury it can be used safely. The FPM should be performed carefully and only if necessary to safely finish the labour or in combination with instrumental delivery.

Obstetric anal sphincter injury following previous vaginal delivery

INTRODUCTION AND HYPOTHESIS

Obstetric anal sphincter injury (OASI) is a debilitating complication of vaginal delivery. The aim of this study was to identify risk factors for OASI in women with a previous vaginal delivery. We further attempted to detect specific risk factors for severe OASI in this subgroup.

METHODS

We conducted a retrospective cohort study between 2003 and 2019. The study group included women who had a singleton, live, vertex, vaginal delivery at term and who also had at least one previous vaginal delivery. The control group included women with at least one previous vaginal delivery without OASI. General medical history, obstetric history, and ante-, intra- and post-partum data were collected and compared between groups.

RESULTS

Following implementation of the inclusion criteria, 79,176 women were included. Allocation to study groups was according to OASI occurrence: 135 patients (0.2%) had a third- or fourth-degree perineal tear, while 79,041 patients (99.8%) had no such injury. Multivariate analysis revealed that one previous vaginal delivery, birthweight ≥ 3900 g (90th percentile), vacuum-assisted vaginal delivery and episiotomy were associated with increased risk of OASI. Comparison of more severe OASI (3C and 4th-degree) cases to the control group showed similar results with the addition of prolonged second stage and younger age to risk factors associated with severe OASI while episiotomy was no longer significant.

CONCLUSION

In women with a previous vaginal delivery, one vs. two or more previous vaginal deliveries, increased birthweight, vacuum-assisted vaginal delivery and episiotomy are risk factors for OASI.