Does episiotomy protect against injury of the levator ani muscle in normal vaginal delivery?

Prevalence of levator ani muscle injuries in primiparous women after delivery and their influence on pelvic floor disorders-systematic review

BACKGROUND

Studies show a significant association between the first vaginal delivery and injuries of the levator ani muscle (LAM), which can cause pelvic floor disorders (PFDs).

OBJECTIVES

This study aims to identify the prevalence of short and long-term LAM injuries after vaginal delivery in primiparous women and its influence on PFDs.

METHOD

A systematic review was conducted according to the PRISMA methodology. The databases used were Pubmed, Cochrane, and PEDro. The quality assessment of the evidence was carried out using the Critical Appraisal Skills Programme (CASP). Both the selection of studies and their evaluation were done by two researchers and a third reviewer in cases of disagreement.

RESULTS

From the search, 57 articles were gathered, and 19 were included to match the eligibility criteria. The prevalence of avulsion of the LAM was found in association with vaginal delivery between 13% and 28% ≤ 1 year after delivery and between 16% and 29% > 1 year after delivery. Ballooning was detected between 20% and 37% ≤ 1 year, and 33% of women > 1 year after delivery, appearing to be more common when compared to avulsion. Pelvic organ prolapse (POP) was considered the most common disorder associated with injuries of the LAM, and there seems to be some connection with sexual dysfunction.

CONCLUSION

Avulsion of the LAM and ballooning of the hiatal area have a high prevalence in primiparous women after vaginal delivery and have a strong direct relation to the development of POP.

Levator Ani Muscle Avulsion After Vaginal Delivery Comparing Routine Versus Restrictive Episiotomy: A Pilot Study

INTRODUCTION AND HYPOTHESIS

The objective was to compare the rate of levator ani muscle avulsion following vaginal birth after routine and restrictive episiotomy.

METHODS

This study consists of two cohorts of pregnant women prospectively enrolled between September 2015 and December 2017 at a university hospital. The pregnant women were subject to a randomized controlled trial, in which participants received a restrictive episiotomy protocol versus a routine episiotomy protocol for vaginal delivery. Levator ani avulsion was evaluated by four-dimensional ultrasound screening.

RESULTS

Sixty-one post-partum primipara women were enrolled in our study. Thirty-two women (52.5%) had undergone routine episiotomy whereas 29 women (47.5%) had gone through restrictive episiotomy. Right mediolateral episiotomies were performed in all cases. The rate of anal sphincter tear was 12.5% in the routine episiotomy group versus 13.8% in the restrictive episiotomy group (p = 1.00). Levator ani avulsion was detected in 9.4% of the routine episiotomy group (only on the right side) and in 10.3% of the restrictive episiotomy group (p = 1.00). No bilateral levator avulsion was detected in either of the groups. There were no statistical differences in the distances of the bladder neck descent, cystocele descent, uterine descent, rectocele descent, and the ballooning of the genital hiatus area between the groups.

CONCLUSIONS

In our pilot study, there was no reduction of the rate of levator ani avulsion in women with restrictive episiotomy compared with routine episiotomy. There were no differences in pelvic floor ultrasound parameters between the two groups.

Diagnosis of maternal birth trauma by pelvic floor ultrasound

BRIEF SUMMARY

Maternal somatic birth trauma due to vaginal delivery is more common than generally assumed and an important cause of future morbidity. Maternal birth trauma may involve both psychological and somatic morbidity, some of it long-term and permanent. Somatic birth trauma is now understood to encompass not just episiotomy, perineal tears and obstetric anal sphincter injuries (OASI), but also trauma to the levator ani muscle, termed 'avulsion'. This review will focus on recent developments in the imaging diagnosis of maternal birth trauma, discuss the most important risk factors and strategies for primary and secondary prevention. Translabial and exo-anal ultrasound allow the assessment of maternal birth trauma in routine clinical practice and enable the use of levator avulsion and anal sphincter trauma as key performance indicators of maternity services. This is likely to lead to a greater awareness of maternal birth trauma amongst maternity caregivers and improved outcomes for patients, not the least due to an increasing emphasis on patient autonomy and informed consent in antenatal and intrapartum care.

Levator ani avulsion: a Systematic evidence review (LASER)

BACKGROUND

There is variation in the reported incidence rates of levator avulsion (LA) and paucity of research into its risk factors.

OBJECTIVE

To explore the incidence rate of LA by mode of birth, imaging modality, timing of diagnosis and laterality of avulsion.

SEARCH STRATEGY

We searched MEDLINE, EMBASE, CINAHL, AMED and MIDIRS with no language restriction from inception to April 2019.

STUDY ELIGIBILITY CRITERIA

A study was included if LA was assessed by an imaging modality after the first vaginal birth or caesarean section. Case series and reports were not included.

DATA COLLECTION AND ANALYSIS

RevMan v5.3 was used for the meta-analyses and SW SAS and STATISTICA packages were used for type and timing of imaging analyses.

RESULTS

We included 37 primary non-randomised studies from 17 countries and involving 5594 women. Incidence rates of LA were 1, 15, 21, 38.5 and 52% following caesarean, spontaneous, vacuum, spatula and forceps births, respectively, with no differences by imaging modality. Odds ratio of LA following spontaneous birth versus caesarean section was 10.69. The odds ratios for LA following vacuum and forceps compared with spontaneous birth were 1.66 and 6.32, respectively. LA was more likely to occur unilaterally than bilaterally following spontaneous (P < 0.0001) and vacuum-assisted (P = 0.0103) births but not forceps. Incidence was higher if assessment was performed in the first 4 weeks postpartum.

CONCLUSIONS

LA incidence rates following caesarean, spontaneous, vacuum and forceps deliveries were 1, 15, 21 and 52%, respectively. Ultrasound and magnetic resonance imaging were comparable tools for LA diagnosis.

TWEETABLE ABSTRACT

Levator avulsion incidence rates after caesarean, spontaneous, vacuum and forceps deliveries were 1, 15, 21 and 52%, respectively.

Ultrasound imaging of maternal birth trauma

INTRODUCTION AND HYPOTHESIS

The term 'maternal birth trauma' has undergone substantial changes in meaning over the last 2 decades. Leaving aside psychological morbidity, somatic trauma is now understood to encompass not just episiotomy, perineal tears and obstetric anal sphincter injuries (OASI), but also trauma to the levator ani muscle. This review covers diagnosis of maternal birth trauma by translabial ultrasound imaging.

METHODS

Narrative review.

RESULTS

Tomographic imaging of pelvic structures with the help of 4D ultrasound, used since 2007, has allowed international standardization and seems to be highly reproducible and valid for the diagnosis of OASI and levator avulsion.

CONCLUSIONS

Translabial and exo-anal ultrasound allows the assessment of maternal birth trauma in routine clinical practice and the utilization of avulsion and sphincter trauma as key performance indicators of maternity services. It is hoped that this will lead to a greater awareness of maternal birth trauma among maternity caregivers and improved outcomes for patients, both in the short term and in the decades to come.

Pelvic floor ultrasound finds after episiotomy and severe perineal tear: systematic review and meta-analysis

AIM

Vaginal delivery is a well-known risk factor for pelvic floor muscle (PFM) injuries, mainly when associated to prolonged labor, instrumental birth and perineal trauma such as episiotomy and perineal tears. The purpose of this meta-analysis was to test the hypothesis that episiotomy and severe perineal tear may increase the risk of pelvic floor damage.

METHODS

We performed a systematic literature search through electronic databases including MEDLINE via PubMed, LILACS via BVS, Embase via Elsevier and Cochrane Library up to January 2019. We included articles that reported as outcome one or more morphological aspects of the PFM evaluated by ultrasonography in primiparous women three to 24 months postpartum. This review is registered in the PROSPERO database (registration number: CRD42017075750).

RESULTS

the final selection was composed of 18 articles for the systematic review, and 10 for the meta-analysis. Women with levator ani muscle (LAM) avulsion were 1.77 times more likely to have undergone episiotomy (OR = 1.77, CI 95% 1.25-2.51, five trials), 4.31 times more likely to have severe perineal tear (OR = 4.31, CI 95% 2.34-7.91, two trials). Women with defects in the anal sphincters were 2.82 times more likely to have suffered severe perineal tear (OR = 2.82, 95% CI 1.71-4.67, three trials).

CONCLUSIONS

Both episiotomy and severe perineal tear are risk factors for LAM avulsion and anal sphincter injury, and this can be useful for identifying women who are at greater risk of developing PFM dysfunctions.

Prevalence of levator ani avulsion in a multicenter study (PAMELA study)

PURPOSE

The objective is to determine the prevalence of levator ani muscle (LAM) avulsion using four-dimensional ultrasound in primiparous women after vaginal delivery and according to delivery mode.

METHODS

This prospective, multicenter study included 322 women evaluated at 6-12 months postpartum by four-dimensional transperineal ultrasound to identify levator ani muscle avulsion. The researcher who performed the ultrasound was blinded to all clinical data. Meaningful data about the birth were also recorded: mode of delivery, mother's age and body mass index, duration of second stage, episiotomy, perineal tearing, anesthesia, assistant, head circumference and fetal weight.

RESULTS

303 volumes were valid for evaluation. The overall prevalence of levator ani muscle avulsion was 18.8% (95% CI 14.4-23.2%). In our multivariate analysis, only mode of delivery reached statistical significance as a risk factor for levator ani muscle avulsion (p < 0.001). The prevalence according to the different modes of delivery was 7.8% in spontaneous delivery, 28.8% in vacuum-assisted and 51.1% in forceps-assisted delivery. Compared with spontaneous delivery, the OR for LAM avulsion was 12.31 with forceps (CI 95% 5.65-26.80) and 4.78 with vacuum-assisted delivery (CI 95% 2.15-10.63).

CONCLUSIONS

Levator ani avulsion during vaginal delivery in primiparous women occurs in nearly one in every five deliveries. Delivery mode is a significant and modifiable intrapartum risk factor for this lesion. The incidence is lower in spontaneous delivery and significantly increases when an instrument is used to assist delivery, especially forceps.

Levator ani muscle morphology and function in women with obstetric anal sphincter injury

OBJECTIVES

To estimate the prevalence of, and explore the risk factors for, levator ani muscle (LAM) injury in women with clinically diagnosed obstetric anal sphincter injury (OASI). The secondary aim was to assess the association between LAM injury and pelvic floor muscle contraction, anal incontinence (AI) and urinary incontinence (UI) in women with OASI.

METHODS

This was a cross-sectional study of 250 women with OASI, recruited between 2013 and 2015 from a tertiary referral center at Croydon University Hospital, UK. AI symptoms were assessed using the modified St Mark's incontinence score and UI was assessed using the International Consultation on Incontinence modular Questionnaire for Urinary Incontinence - Short Form. All participants underwent three/four-dimensional transperineal ultrasound at rest and on maximum pelvic floor muscle contraction. Major LAM injury was defined as a unilateral or bilateral defect in all three central slices on tomographic ultrasound imaging. Muscle contraction was assessed using the modified Oxford scale (MOS) and measured on ultrasound as the proportional change in the anteroposterior (AP) levator hiatal diameter between rest and contraction. Multivariable logistic regression analysis was used to study risk factors for LAM injury. Differences in contraction and AI and UI symptoms between women with intact and those with injured LAM were studied using multivariable ANCOVA and the Mann-Whitney U-test.

RESULTS

Of the 248 women with OASI for whom ultrasound volumes of adequate quality were available, 29.4% were found to have major LAM injury. The prevalence of LAM injury was 23.6% after normal vaginal delivery and 40.2% after operative vaginal delivery (adjusted odds ratio, 4.1 (95% CI, 1.4-11.9); P = 0.01). LAM injury was associated with weaker pelvic floor muscle contraction, with an adjusted mean difference for proportional change in AP diameter of 5.0 (95% CI, 3.0-6.9) and MOS of 0.6 (95% CI, 0.3-0.9) (P < 0.001 for both). AI and UI symptom scores were similar between women with intact and those with injured LAM.

CONCLUSIONS

Operative vaginal delivery was a risk factor for LAM injury in women with OASI. LAM injury was associated with weaker pelvic floor muscle contraction. Special attention is recommended for women with OASI and LAM injury, as they are at high risk for future pelvic floor disorders. The benefits of implementation of an intensive, focused and structured pelvic floor rehabilitation program need to be evaluated in these women. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Delivery mode and the risk of levator muscle avulsion: a meta-analysis

INTRODUCTION AND HYPOTHESIS

Female pelvic organ prolapse (POP) is a common condition, with a lifetime risk for surgery of 10-20%. Pregnancy and childbirth are the commonest modifiable risk factors for POP, and avulsion of the levator ani muscle is likely to be an etiological factor. Avulsion is more common in instrumental delivery. However, we were unable to identify a meta-analysis on this issue. Our aim was to perform a systemic review and quantitative meta-analysis of the prevalence of avulsion relative to delivery mode.

METHODS

Four electronic databases (MEDLINE, PubMed, Embase, and Google Scholar) were searched for studies published between 1991 and 1 October 2018 without language restrictions.

RESULTS

Twenty studies met inclusion criteria, and 14 were prospective. Seventeen used sonographic techniques; three were magnetic resonance (MR) studies. For this review, three comparisons were performed: forceps vs. vacuum (9 studies), forceps vs. normal vaginal delivery (NVD) (12 studies), and vacuum vs. NVD (12 studies). The first meta-analysis showed an increased risk for avulsion following forceps compared with vacuum, with an odds ratio (OR) of 4.57 and confidence interval (CI) 3.21-6.51, p < 0.001. The second showed an increased risk for avulsion following forceps compared with NVD, with an OR of 6.94 (4.93-9.78), p < 0.001. The third showed no significant increased risk for avulsion following vacuum compared with NVD, with an OR of 1.31 (1.00-1.72), p = 0.051.

CONCLUSIONS

Forceps is a strong risk factor for avulsion, with an OR of 6.94 (4.93-9.78) compared with NVD and an OR of 4.57 (3.21-6.51) compared with vacuum birth.

Association of levator injury and urogynecological complaints in women after their first vaginal birth with and without mediolateral episiotomy

BACKGROUND

Pelvic organ prolapse is a common health problem in women and has a negative influence on quality of life. A major cause of pelvic organ prolapse is levator injury.

OBJECTIVE

The objective of the study was to evaluate the association of mediolateral episiotomy with levator injury (levator avulsion, ballooning, or combined) and urogynecological complaints.

STUDY DESIGN

A prospective observational cohort study was performed in 204 primiparous women with a spontaneous vaginal delivery without anal sphincter tear in a general hospital between 2012 and 2015. One hundred three of these women had had a mediolateral episiotomy. Validated urogynecological questionnaires and transperineal 3-dimensional/4-dimensional ultrasound were completed after delivery. Outcome measures were levator avulsion, ballooning (hiatal area of more than 25 cm²), and urogynecological questionnaire scores. Statistical analysis was performed using univariate and multiple logistic regression analysis.

RESULTS

The median time at investigation after vaginal delivery was 13 months (range 6-33). Levator injury (avulsion, ballooning, or combined) was identified in 35 of the 103 women who had undergone mediolateral episiotomy (40.0%) and 33 of the 101 women without episiotomy (32.7%) (P = .69). No differences were found in the incidence of levator avulsion 27 (26.7%) vs 23 (22.8%) (P = .53) or in levator ballooning (20 [19.4%] vs 23 [22.8%] (P = .58) between both groups. There was an association between longer duration of the second stage of labor and the incidence of levator avulsion (odds ratio, 1.24 [95% confidence interval, 1.01-1.52]). Nonocciput anterior fetal position increased the risk of levator ballooning and levator injury (odds ratio, 10.19 [95% confidence interval, 1.89-54.91] and odds ratio, 12.16 [95% confidence interval, 1.41-104.38], respectively). No differences in urogynecological complaints were found.

CONCLUSION

Mediolateral episiotomy is not associated with the occurrence of levator injury or urogynecological complaints in women with a spontaneous vaginal delivery who did not obtain an anal sphincter injury. Levator injury was associated with a prolonged second stage of labor and a nonocciput anterior fetal position.

On the variation in maternal birth canal in vivo viscoelastic properties and their effect on the predicted length of active second stage and levator ani tears

The pubovisceral muscles (PVM) help form the distal maternal birth canal. It is not known why 13% of vaginal deliveries end in PVM tears, so insights are needed to better prevent them because their sequelae can lead to pelvic organ prolapse later in life. In this paper we provide the first quantification of the variation in in vivo viscoelastic properties of the intact distal birth canal in healthy nulliparous women using Fung's Quasilinear Viscoelastic Theory and a secondary analysis of data from a clinical trial of constant force birth canal dilation to 8 cm diameter in the first stage of labor in 26 nullipara. We hypothesized that no significant inter-individual variation would be found in the long time constant, τ_2, which characterizes how long it takes the birth canal to be dilated by the fetal head. That hypothesis was rejected because τ₂ values ranged 20-fold above and below the median value. These data were input to a biomechanical model to calculate how such variations affect the predicted length of the active second stage of labor as well as PVM tear risk. The results show there was a 100-fold change in the predicted length of active second stage for the shortest and longest τ₂ values, with a noticeable increase for τ₂ values over 1000 s. The correlation coefficent between predicted and observed second stage durations was 0.51. We conclude that τ₂ is a strong theoretical contributor to the time a mother has to push in order to deliver a fetal head larger than her birth canal, and a weak predictor of PVM tear risk.

Longitudinal follow-up of levator ani muscle avulsion: does a second delivery affect it?

OBJECTIVES

To evaluate the morphological outcome of levator ani muscle (LAM) avulsion 3-5 years after a first delivery and to assess the effect of a second delivery on this condition. The impact of LAM avulsion on pelvic floor disorders was also studied.

METHODS

Six hundred and sixty-six women who had been assessed for LAM avulsion 8 weeks after their first delivery were invited for a follow-up examination 3-5 years later. Women completed the Pelvic Floor Distress Inventory including the Urinary Distress Inventory (UDI) and Pelvic Organ Prolapse Distress Inventory (POPDI) questionnaires to explore symptoms of pelvic floor disorders, and the pelvic floor was examined using three-dimensional translabial ultrasound and assessed using the pelvic organ prolapse quantification system.

RESULTS

Three hundred and ninety-nine women completed the study, of whom 151 were multiparous. Mean interval between first delivery and follow-up was 42.3 ± 7.6 months. Among 69 women who had LAM avulsion 8 weeks after their first delivery, nine (13.0%) had no LAM avulsion at follow-up. One (0.9%) woman had a new LAM avulsion after her second vaginal delivery. A greater proportion of women with LAM avulsion reported symptoms of stress urinary incontinence (SUI) (adjusted odds ratio, 2.09 (95% CI, 1.18-3.70); P = 0.01) and symptoms of prolapse than did women without avulsion; however, this difference did not reach statistical significance (P = 0.61). Women with LAM avulsion had higher UDI and POPDI scores than did women without avulsion (median UDI score, 17.7 (interquartile range (IQR), 5.0-32.4) vs 9.2 (IQR, 0.0-22.1); P = 0.045 and median POPDI score, 20.8 (IQR, 8.8-40.5) vs 10.7 (IQR, 0.0-32.8); P = 0.021).

CONCLUSIONS

The risk of developing new LAM avulsion after a second vaginal delivery is low (0.9%). Healing of LAM avulsion was observed in 13% of women who had at least one vaginal delivery. At 3-5 years after delivery, women with LAM avulsion reported symptoms of SUI more often than did those without, and had higher UDI and POPDI scores, implying more bothersome symptoms. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.