Obstetrical situations with a high risk of anal sphincter laceration in vacuum-assisted deliveries

Mediolateral/lateral episiotomy with operative vaginal delivery and the risk reduction of obstetric anal sphincter injury (OASI): A systematic review and meta-analysis

Introduction and hypothesis

OASI complicates approximately 6% of vaginal deliveries. This risk is increased with operative vaginal deliveries (OVDs), particularly forceps. However, there is conflicting evidence supporting the use of mediolateral/lateral episiotomy (MLE/LE) with OVD. The aim of this study was to assess whether MLE/LE affects the incidence of OASI in OVD.

Methods

Electronic searches were performed in OVID Medline, Embase and the Cochrane Library. Randomised and non-randomised observational studies investigating the risk of OASI in OVD with/without MLE/LE were eligible for inclusion. Pooled odds ratios (OR) were calculated using Revman 5.3. Risk of bias of was assessed using the Cochrane RoB2 and ROBINS-I tool. The quality of evidence was assessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE).

Results

A total of 703,977 patients from 31 studies were pooled for meta-analysis. MLE/LE significantly reduced the rate of OASI in OVD (OR 0.60 [95% CI 0.42–0.84]). On sub-group analysis, MLE/LE significantly reduced the rate in nulliparous ventouse (OR 0.51 [95% CI 0.42–0.84]) and forceps deliveries (OR 0.32 [95% CI 0.29–0.61]). In multiparous women, although the incidence of OASI was lower when a ventouse or forceps delivery was performed with an MLE/LE, this was not statistically significant. Heterogeneity remained significant across all studies (I² > 50). The quality of all evidence was downgraded to “very low” because of the critical risk of bias across many studies.

Conclusions

MLE/LE may reduce the incidence of OASI in OVDs, particularly in nulliparous ventouse or forceps deliveries. This information will be useful in aiding clinical decision-making and counselling in the antenatal period and during labour.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00192-022-05145-1.

A retrospective study of the incidence and predisposing factors of third- and fourth-degree perineal tears

OBJECTIVES

To evaluate the rates of third- and fourth-degree tears and related predisposing factors for the tears in singleton vaginal deliveries. Methods: This was a retrospective study of third- and fourth-degree perineal tears in all women who underwent vaginal delivery in a tertiary hospital in Assir region between January 2014 and December 2019. There are approximately 5000 deliveries per year at the Abha Maternity and Children Hospital. The total number of deliveries during the study period was 31,788, of which 19,374 were delivered vaginally. Results: A total of 85 women (0.43% of all vaginal deliveries) had third-degree (n=81) or fourth-degree (n=4) perineal tears. The mean age of the women was 31 years (range: 16-46 years). Fifty-two of the 85 women (61%) were primiparous. Of the various obstetric parameters, episiotomy, occipitoposterior presentation, primigravida, multipara, and a previous episiotomy were found to be significant predisposing factors to third- and fourth-degree tears in our patients.

CONCLUSION

The low incidence of obstetric anal sphincter injuries in this study is likely the result of proactive manual protection of the perineum, valid indications for episiotomy, and attendance of senior staff members at all difficult deliveries.

The role of mediolateral episiotomy during vacuum-assisted vaginal delivery with soft cup devices

PURPOSE

This study evaluated whether episiotomy during vacuum-assisted delivery leads to fewer third- and fourth-degree tears.

METHODS

This was a retrospective cohort study of all nulliparas who underwent a singleton, soft cup, vacuum-assisted vaginal delivery in one institution, from January 2014 to August 2019. Failed vacuum deliveries were excluded. Based on power analysis calculation, a sample size of 500 women in each group was sufficient to detect an advantage of episiotomy, if present. Primary outcome was third- or fourth-degree perineal tear. Secondary outcomes were other maternal complications, and low neonatal cord pH and Apgar scores. Outcomes were compared between women with and without episiotomy.

RESULTS

During the study period, 2370 nulliparas had a vacuum-assisted vaginal delivery using soft vacuum cup and met the study inclusion criteria. Episiotomy was performed in 1868 (79%) women, and 502 (21%) delivered without episiotomy. Background characteristics were similar in both groups. There were no significant differences in the rates of third and fourth grade perineal lacerations between the two groups. Episiotomy was associated with higher rate of postpartum hemorrhage (p < 0.01) CONCLUSIONS: Using selective episiotomy for patients delivering vaginally with the assistance of soft cap vacuum does not increase third- or fourth-degree perineal tears.

Predictors of obstetric anal sphincter injury during waterbirth: a secondary analysis of a prospective observational study

INTRODUCTION AND HYPOTHESIS

Obstetric anal sphincter injury (OASI) during childbirth is associated with urino-genital pain and dysfunction. Waterbirth is a popular birth choice for women, but controversy remains around the risk of OASI during waterbirth. This study reports on the incidence of OASI, and factors associated with OASI, for a cohort of women who gave birth in water.

METHODS

This secondary analysis used prospectively collected data from 2,908 women who gave birth in water in a hospital setting. The incidence of OASI was calculated. Univariable and multivariable logistic regression analysis evaluated factors associated with OASI.

RESULTS

The incidence of OASI was 1.9% (95% confidence interval (CI) 1.4, 2.4) for all women. In nulliparae it was higher (3.2%, 95% CI 2.3, 4.3) than in multiparae (0.9%, 95% CI 0.5, 1.4). In the multivariable analysis, two variables were associated with OASI; multiparity was negatively associated with OASI (adjusted odds ratio [aOR] 0.24, 95% CI 0.12, 0.50, p < 0.001), and birth weight was positively associated with OASI (aOR 1.001, 95% CI 1.000, 1.002, p = 0.02). A "hands-on" technique was used during only 13% of births. A birth position supporting a flexible sacrum did not influence OASI risk.

CONCLUSIONS

A low incidence of OASI was found for this cohort of women. The low proportion of midwives using a hands-on technique suggests that it may not be required in waterbirth.

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

INTRODUCTION

Delivery by vacuum extraction is a major risk factor for obstetric anal sphincter injury. The aim of this study was to assess risk factors for obstetric anal sphincter injury in vacuum extraction in nulliparous women, specifically operator-related factors. A secondary aim was to assess other complications of vacuum extraction that are dependent on operator experience.

MATERIAL AND METHODS

A historical cohort study of nulliparous women with a live single fetus ≥34 weeks, delivered by vacuum extraction at a teaching hospital in Sweden in 1 year (2013), using data from medical records. Risk of obstetric anal sphincter injury was assessed for obstetricians (reference), gynecologists, and residents, and adjusted for maternal, fetal, procedure-related, and operator-related covariates using unconditional logistic regression. Results are presented as prevalence and crude and adjusted odds ratio (aOR) with 95% CI.

RESULTS

In total, 323 nulliparous women delivered by vacuum extraction were included. Obstetric anal sphincter injury occurred in 57 (17.6%) women. Fifteen (11.5%) obstetric anal sphincter injuries occurred in vacuum extractions performed by obstetricians, 10 (13.5%) by gynecologists (aOR 1.84, 95% CI 0.72-4.70), and 32 (26.9%) by residents (aOR 5.13, 95% CI 2.20-11.95). Maternal height ≤155 cm (aOR 4.63, 95% CI 1.35-15.9) and conversion to forceps (aOR 19.4, 95% CI 1.50-252) increased the risk of obstetric anal sphincter injury. Operator gender, night shift work, or being a frequent operator did not affect the risk of obstetric anal sphincter injury. Postpartum hemorrhage and fetal complications did not differ between operator categories.

CONCLUSIONS

The adjusted risk of obstetric anal sphincter injury in nulliparous women was five times higher in vacuum extractions performed by residents compared with those performed by obstetricians. Vacuum extractions performed by gynecologists did not carry an increased risk of obstetric anal sphincter injury. Experience in years of training, rather than frequency of the procedure, seemed to have the highest impact on reducing obstetric anal sphincter injury in vacuum extractions, which indicates a need for increased training and supervision.

Relation between Epidural Analgesia and severe perineal laceration in childbearing women in Catalonia

OBJECTIVE

Our objectives were to study the association between epidural analgesia and risk of severe perineal laceration (SPL), and identify additional risk factors for SPL. This multicentre study consisted of an analysis of data from the MidconBirth Phase I Database, on the use of EA and perineal results during childbirth. (World Health Organization, International Clinical Trials Registry Platform, 2016: http://apps.who.int/trialsearch/Trial2.aspx?TrialID=ISRCTN17833269).

METHODS

We conducted a prospective study of pregnant women at term between July 2016 and July 2017 in 30 public maternity hospitals in Catalonia, Spain. Inclusion criteria were an uncomplicated singleton pregnancy, in cephalic presentation and vaginal birth. Data was analysed separately for instrumental births and spontaneous vaginal births, as the former is more frequently associated with episiotomy and more perineal lacerations. Risk factors as well as protective factors in each cohort of women (instrumental and spontaneous vaginal birth), were identified. Multivariate logistic regression model was performed to study the association between epidural analgesia and SPL to identify potential confounders. Odds ratios (OR), using 95% confidence intervals (CI) were constructed.

FINDINGS

During the study period, 5497 eligible women gave birth, 77.46% of them received epidural analgesia. SPL occurred in 1.63% of births. The univariate analysis showed births with epidural analgesia had significantly higher rates of inductions, augmentation of labour, lithotomy position for birth and episiotomy. However, this association disappeared when the variable "type of vaginal birth" was introduced. In multivariate logistic regression, nulliparity was the major predictor for SPL (OR: 0.17; CI 95%: 0.08-0.34, p: 0.000).

KEY CONCLUSIONS

Epidural analgesia was not associated with SPL once confounding factors were included. Other interesting factors associated with SPL were identified.

IMPLICATIONS FOR PRACTICE

This paper identifies important practice areas which contribute to SPL and which have the potential to be rectified. It offers evidence on the role that EA plays on pelvic floor injuries and it adds to existing evidence about the disadvantages of using the lithotomy position for birth, especially in relation to SPL. It highlights the need for practice change in Catalonia from what can be considered a medical model of care to one more aligned with the midwifery philosophy of care through the development of clinical guidelines. It also signals the need to provide women with evidence base upon which to make informed choices on the use of EA, specifically in relation to SPL.

[Obstetrical anal sphincter injuries and vacuum-assisted delivery at term in primiparas]

OBJECTIVES

Operative Vaginal Delivery (OVD) is subject to a risk of perineal tears especially of Obstetrical Anal Sphincter Injuries (OASIS) that are associated with more complications and impaired quality of life. The main objective of this study was to compare the rate of OASIS in primipara at term with fetus in cephalic presentation depending on the type of delivery: OVD using vacuum extractor and spontaneous delivery.

METHODS

This is a single-center retrospective study between 01/01/2010 and 12/31/2014 including all primipara who delivered vaginally at term, a single and living fetus in cephalic presentation. Perineal lesions were classified according to the WHO classification. The primary endpoint was the proportion of OASIS.

RESULTS

3552 patients were included: 2496 spontaneous deliveries (SD) and 1056 OVD (29.72 %). There were twenty sphincter tears (0.56 %): 7 in SD group (0.28 %) and 13 in OVD (1.23 %), P<0.0001, OR=5.10 [2.00; 12.99]. Other risk factors associated with OASIS in univariable analysis were: maternal age (≥30 years), duration of expulsive efforts (≥20min) and a birth weight≥4000g.

CONCLUSION

In these patients, the risk of OASIS in case of AI increases by a factor of 5;10. The high rate of AI in these patients exposes them to a real risk of OASIS. However, the proportion of OASIS in this group remains lower than those reported in the literature and is barely higher than the national overall rate, despite a very restrictive policy of the use of episiotomy.

Incidence and risk factors of third- and fourth-degree perineal tears in a single Italian scenario

OBJECTIVE

This study aimed to evaluate III and IV degree tears rates and related risk factors in a single Italian centre. The secondary goal was to build a predictive model based on identified risk factors.

STUDY DESIGN

This was a retrospective cohort study. All vaginal deliveries from 2011 to 2015 in a single Italian University Hospital were analysed. Univariate analysis was applied to evaluate the overall association between each factor and severe tear. Multivariate logistic regression was used to build a predictive model for the absolute risk of severe tear. We computed a resampling validated measure (AUC) of the predictive accuracy of the model and we provided a nomogram for the risk calculation in clinical practice.

RESULTS

62 out of 10133 patients (0.61%) had a severe perineal tear. Univariate analysis identified gestational age >40 weeks, nulliparity, moderate/severe obesity, oxytocin use in pushing stage, sinciput presentation, instrumental delivery, shoulder dystocia, pushing stage ≥90 min, lithotomy position, birth weight >4 kg, head circumference at birth >34 cm and length at birth >50 cm as risk factors. Multivariate analysis identify moderate/severe obesity (OR = 2.8), instrumental delivery (OR = 2.6) and birth weight (OR = 1.1/hg) as independent risk factors. Using the predicted risk score from the final model (bootstrap-validated AUC 70%), we designed a nomogram for severe perineal tears absolute risk calculation.

CONCLUSION

Moderate/severe obesity, instrumental delivery and foetal weight resulted as independent risk factors for severe obstetrical tears.

Episiotomy Technique and Management of Anal Sphincter Tears-A Survey of Clinical Practice and Education

OBJECTIVE

To ascertain current techniques of episiotomy used by obstetrics and gynaecology faculty members and residents in an academic department and to determine the current management strategies for third and fourth degree tears.

METHOD

A 14-question anonymous online survey was circulated to all faculty members and residents in the University of Toronto Department of Obstetrics and Gynaecology between October 2015 and March 2016. Results were analyzed descriptively or with Fisher exact test.

RESULTS

The survey response rate was 65.5% (169/258) among 108 faculty members and 61 residents. A history of clinical teaching regarding episiotomy was reported by 87% of faculty members and 75.4% of residents. Right mediolateral episiotomy was the most frequently used method among faculty members (88.0%) and residents (95.1%). The majority of respondents indicated that they would use an end-to-end technique for repair in the labour and delivery room under regional anaesthesia. Prophylactic antibiotics were never prescribed by 18.5% of faculty members and 13.1% of residents for third or fourth degree tears. In analysis by type of training, respondents who had taken a workshop or formal class were significantly more likely to prescribe physiotherapy postpartum (P = 0.001).

CONCLUSION

The most common reported method of learning episiotomy was clinical experience. A substantial number of responses differed from current SOGC guidelines for episiotomy technique and repair and management of anal sphincter injury. We propose developing a workshop and/or simulation-based method of instruction for episiotomy technique and repair.

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.

[Methods of pushing at vaginal delivery and pelvi-perineal consequences. Review]

INTRODUCTION

The main objective of that review was to evaluate the pelvi-perineal consequences of the different methods of pushing at vaginal delivery.

METHODS

A review on PubMed, the Cochrane Library and EM-Premium was performed from 1984 to 2014. Among 29 manuscripts analysed, only nine randomised controlled trials (including one meta-analysis of three trials) comparing Valsalva and spontaneous pushing were selected. A 10 th study, secondary analysis of a randomized controlled trial comparing different methods of perineal protection (warm compresses, massage and manual protection), was also selected.

RESULTS

Two trials have shown that spontaneous pushing reduces the risk of perineal tears, but studies were heterogeneous and discordant results do not allowed definitive conclusions. Results on the duration of the second stage of labour are conflicting. The method of pushing does not seem to affect the rate of episiotomy, instrumental delivery and cesarean section. Maternal satisfaction seems to be better after spontaneous pushing. It seems that there is no negative effect of spontaneous pushing on neonate well-being, and one study has shown a significant improvement of prenatal fetal parameters during the expulsive phase.

CONCLUSION

According to current knowledge, both techniques of pushing during the expulsive phase at delivery seem comparable in terms of duration, risk of perineal tears and neonatal outcome.

Incidence of and risk factors for perineal trauma: a prospective observational study

BACKGROUND

Our aim was to describe the range of perineal trauma in women with a singleton vaginal birth and estimate the effect of maternal and obstetric characteristics on the incidence of perineal tears.

METHODS

We conducted a prospective observational study on all women with a planned singleton vaginal delivery between May and September 2006 in one obstetric unit, three freestanding midwifery-led units and home settings in South East England. Data on maternal and obstetric characteristics were collected prospectively and analysed using univariable and multivariable logistic regression. The outcome measures were incidence of perineal trauma, type of perineal trauma and whether it was sutured or not.

RESULTS

The proportion of women with an intact perineum at delivery was 9.6% (125/1,302) in nulliparae, and 31.2% (453/1,452) in multiparae, with a higher incidence in the community (freestanding midwifery-led units and home settings). Multivariable analysis showed multiparity (OR 0.52; 95% CI: 0.30-0.90) was associated with reduced odds of obstetric anal sphincter injuries (OASIS), whilst forceps (OR 4.43; 95% CI: 2.02-9.71), longer duration of second stage of labour (OR 1.49; 95% CI: 1.13-1.98), and heavier birthweight (OR 1.001; 95% CI: 1.001-1.001), were associated with increased odds. Adjusted ORs for spontaneous perineal truama were: multiparity (OR 0.42; 95% CI: 0.32-0.56); hospital delivery (OR 1.48; 95% CI: 1.01-2.17); forceps delivery (OR 2.61; 95% CI: 1.22-5.56); longer duration of second stage labour (OR 1.45; 95% CI: 1.28-1.63); and heavier birthweight (OR 1.001; 95% CI: 1.000-1.001).

CONCLUSIONS

This large prospective study found no evidence for an association between many factors related to midwifery practice such as use of a birthing pool, digital perineal stretching in the second stage, hands off delivery technique, or maternal birth position with incidence of OASIS or spontaneous perineal trauma. We also found a low overall incidence of OASIS, and fewer second degree tears were sutured in the community than in the hospital settings. This study confirms previous findings of overall high incidence of perineal trauma following vaginal delivery, and a strong association between forceps delivery and perineal trauma.