Four-dimensional sonographic evaluation of avulsion of the levator ani according to delivery mode

Obstetric risk factors for levator ani muscle avulsion: A systematic review and meta-analysis

OBJECTIVES

Women have a 11% lifetime risk of undergoing surgery for vaginal prolapse. Levator ani muscle (LAM) avulsion is one etiological factor associated with primary and recurrent pelvic organ prolapse. Pelvic organ prolapse has been shown to greatly affect the quality of life and well-being of women. Conduct a meta-analysis identifying risk factors associated with LAM avulsion recognised on transperineal ultrasound (TPUS) or magnetic resonance imaging (MRI) in primiparous women after vaginal birth.

STUDY DESIGN

OVID Medline, Embase and the Cochrane Library from inception to January 2021 were searched. Review Manager 5.3 (The Cochrane Collaboration) was used to analyse data. Odds ratios (OR) with 95% confidence intervals (95% CIs) were calculated. The heterogeneity among studies was calculated using the I2statistic.

RESULTS

Twenty-five studies were eligible for inclusion (n = 9333 women). Major LAM avulsion was diagnosed in an average of 22 % (range 12.7-39.5 %) of cases. Twenty-two studies used TPUS and three used MRI to diagnose avulsion. Modifiable and non-modifiable risk factors were identified. Significant predictors identified were forceps (OR 6.25 [4.33 - 9.0]), obstetric anal sphincter injuries (OR 3.93 [2.85-5.42]), vacuum (OR 2.41 [1.40-4.16]), and maternal age (OR 1.06 [1.02-1.10]).

CONCLUSIONS

This is the first meta-analysis of both modifiable and non-modifiable risk factors associated with LAM avulsion. This information could be used to develop a clinically applicable risk prediction model to target postnatal women at risk of LAM avulsion with a view to prevent the onset of pelvic floor organ prolapse.

Risk factors for postpartum stress urinary incontinence: a prospective study

PURPOSE

Postpartum stress urinary incontinence (SUI) is a common occurrence in women, and it has a profound effect on women's health and quality of life. This study aimed to investigate the risk factors for postpartum SUI and the relative importance of each factor, including pelvic floor ultrasound measurement data and clinical data.

METHOD

Pregnant women who delivered in our hospital from March 2021 to January 2022 were selected as the study population. The clinical and anatomical Data from women with SUI and those without SUI were collected and analyzed. The clinical and anatomical risk factors associated with postpartum SUI were identified using univariate and multivariate analyses.

RESULTS

A total of 255 participants were recruited. Logistic regression analysis indicated that age (OR:1.215, 95% CI:1.097-1.346, P < 0.001), vaginal delivery (OR:3.05, 95% CI:1.328-7.016, P < 0.009), parity (OR:3.059, 95% CI:1.506-6.216, P < 0.002), bladder neck descent (OR:4.159, 95% CI: 2.010-8.605, P < 0.001), the angle of the internal urethral orifice funnel (OR:1.133, 95% CI:1.091-1.176, P < 0.001) were important independent risk factors for postpartum SUI (all P < 0.05). The AUC was 0.883 (95% CI: 0.839-0.926) in the model.

CONCLUSIONS

Age, vaginal delivery, parity, bladder neck descent and the angle of the internal urethral orifice funnel are independent risk factors for postpartum SUI. To prevent the occurrence of postpartum SUI, high-risk factors of postpartum SUI should be identified as early as possible during pregnancy and after delivery, and postpartum pelvic floor rehabilitation training should be promoted.

Ultrasound examination of the pelvic floor during active labor: A longitudinal cohort study

INTRODUCTION

There is limited evidence about changes in the pelvic floor during active labor. We aimed to investigate changes in hiatal dimensions during the active first stage of labor and associations with fetal descent and head position.

MATERIAL AND METHODS

We conducted a longitudinal, prospective cohort study at the National University Hospital of Iceland, from 2016 to 2018. Nulliparous women with spontaneous onset of labor, a single fetus in cephalic presentation, and gestational age ≥37 weeks were eligible. Fetal position was assessed with transabdominal ultrasound and fetal descent was measured with transperineal ultrasound. Three-dimensional volumes were acquired from transperineal scanning at the start of the active phase of labor and in late first stage or early second stage. The largest transverse hiatal diameter was measured in the plane of minimal hiatal dimensions. The levator urethral gap was measured as the distance between the center of the urethra and the levator insertion using tomographic ultrasound imaging. Measurements of the levator urethral gap were made in the plane of minimal hiatal dimensions and 2.5 and 5 mm cranial to this.

RESULTS

The final study population comprised 78 women. The mean transverse hiatal diameter increased 12.4% between the two examinations, from 39.4 ± 4.1 mm (±standard deviation) at the first examination to 44.3 ± 5.8 mm at the last examination (p < 0.01). We found a moderate correlation between the transverse hiatal diameter and fetal station at the last examination (r = 0.44, r2  = 0.19; p < 0.01; regression equation y = 2.71 + 0.014x), and a weak correlation between the change in transverse hiatal diameter and change in fetal station (r = 0.29; r2  = 0.08; p = 0.01; regression equation y = 0.24 + 0.012x). Levator urethral gap increased significantly in all three planes on both the left and right sides. Head position was not associated with hiatal measurements after adjusting for fetal station.

CONCLUSIONS

We found a significant, but only modest, increase of the hiatal dimensions during the first stage of labor. The risk of levator ani trauma will therefore be low during this stage. The change in transverse hiatal diameter was associated with fetal descent but not with head position.

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.

Adding Insult to Injury: Levator Ani Avulsion in Women With Obstetric Anal Sphincter Injuries

OBJECTIVE

In women with obstetric anal sphincter injuries, we compared the rate of major levator ani avulsion after forceps-assisted delivery versus spontaneous vaginal delivery.

METHODS

Prospective cohort of primiparous women with obstetric anal sphincter injuries. The primary outcome was the rate of major levator ani avulsion as measured by 3-dimensional transvaginal ultrasonography performed between 1 and 2 weeks postpartum. Secondary outcomes included ultrasonographic anteroposterior hiatal diameter, levator hiatal area, and levator-urethra gap, and differences in validated pelvic disorder questionnaires scores at 1 to 2 and 13 weeks postpartum.

RESULTS

Sixty-two women (30 spontaneous deliveries, 32 forceps deliveries) were included in the final analysis. After controlling for delivery variables, women who underwent forceps-assisted delivery were more likely to experience a major avulsion as compared with those who underwent spontaneous delivery (21/32, [65.6%] vs 8/30 [26.7%]; odds ratio, 5.9; 95% confidence interval, 1.5-24.5; P = 0.014). They were also more likely to have larger levator-urethra gaps bilaterally (P = 0.012, 0.016). After controlling for potential confounders, levator ani avulsion was independently associated with persistent anal incontinence symptoms at 13 weeks postpartum (P = 0.02).

CONCLUSIONS

In women with obstetric anal sphincter injuries, the risk of levator ani avulsion is almost 6 times higher after forceps-assisted vaginal delivery as compared with spontaneous vaginal delivery. In those with avulsion, recovery of anal continence is compromised, suggesting that adding insult (avulsion) to injury (obstetric anal sphincter injury) may have negative functional consequences.

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.

Contributing factors in forceps associated pelvic floor trauma

INTRODUCTION AND HYPOTHESIS

Levator avulsion occurs in 10-35% of women after a first vaginal delivery, with forceps being the main risk factor. Three mechanisms have been proposed to account for the high risk of trauma: the additional space requirement, increased speed of distension, and/ or greater force. This study examines the additional space requirements associated with forceps to determine any associated increase in avulsion risk.

METHODS

This was an in vitro simulation study of spatial requirements for delivery of a fetal head by forceps, with mathematical modelling of spatial requirements using data from a local observational study. A balloon device was used to model head circumferences through the range of expected measurements at term, with measurements taken after application of three different types of forceps. Each measurement was performed in triplicate.

RESULTS

On average, forceps increased the circumference of the fetal head by 1.01 cm for Wrigley's, 1.04 cm for Kielland's, and 1.64 cm for Neville-Barnes forceps, resulting in an estimated increase in the diameter of the fetal head by 0.32 cm, 0.33 cm, and 0.52 cm, respectively. This increase was linear throughout the tested range. In 534 singleton pregnancies at term, we determined an odds ratio (OR) of 1.11 per centimeter head circumference for avulsion. Hence, the additional space requirement due to forceps explains ORs of 1.11, 1.12, and 1.19 for avulsion, depending on forceps type.

CONCLUSIONS

The effect of forceps on avulsion risk is not fully explained by the increase in space requirement alone. Other factors, such as shortened time to maximum distension and/or increased peak force applied may contribute to the excess risk.

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.

[Childbirth pelvic floor trauma: Anatomy, physiology, pathophysiology and special situations - CNGOF perineal prevention and protection in obstetrics guidelines]

OBJECTIVES

To assess whether pelvic size and shape, spinal curvature, perineal body length and genital hiatus size are associated with the incidence of childbirth pelvic floor trauma. Special situations, such as obesity, ethnicity and hyperlaxity, will also be studied.

METHODS

A bibliographic research using Pubmed and Cochrane Library databases was conducted until May 2018. Publications in English and French were selected by initial reading of the abstracts. Randomized trials, meta-analyzes, case-control studies and large cohorts were studied in a privileged way.

RESULTS

A pubic arch angle<90° (measured clinically) does not appear to increase the risk of OASIS (Level 3), but appears to be a risk factor for postnatal anal incontinence at short-term, but not at long-term (Level 3). Measurement of pelvic dimensions and the subpubic angle is not recommended to predict OASIS or to choose the mode of delivery for the purpose of protecting the perineum (GradeC). Prenatal measurement of both perineal body (Level 3) and genital hiatus (Level 2) does not predict the incidence of 2nd or 3rd degree OASIS. Therefore, the routine prenatal measurement of the length of the perineal body or the genital hiatus is not recommended for any objective related to perineal protection (Grade C). Levator avulsion, resulting in a widening of the genital hiatus, is potentially a source of long-term pelvic floor dysfunction. Biomechanical models suggest that performing a mediolateral episiotomy and applying the fingers to the posterior perineum at the time of expulsive phase may reduce pelvic floor trauma. Obese women have a longer perineal body (Level 3), and obesity does not seem to increase the risk of OASIS (Level 2). There is no difference between Asian and non-Asian women perineal body (Level 3). No studies have validated that the liberal practice of episiotomy in Asian women reduced the risk of OASIS. It is therefore not recommended to practice an episiotomy for simple ethnic reasons in Asian women (GradeC). Compared to white women, black women do not appear to have an increased risk of OASIS and even appear to have a decreased risk of perineal tears of all stages (Level 2). Ligament hyperlaxity seems to be associated with an increased risk of OASIS (Level 2).

CONCLUSIONS

Prenatal assessment of pelvis bone, spine curvature, perineal body and genital hiatus do not allow to predict the incidence of childbirth pelvic floor trauma. Obesity and ethnicity are not risk factors for OASIS.

Three-dimensional/four-dimensional transperineal ultrasound: clinical utility and future prospects

During the last decade, there has been a huge advancement in the use of transperineal ultrasound (TPU) in the field of obstetrics and gynecology. Its main applications in obstetrics include the monitoring of fetal progression in labor and recently the assessment of maternal pelvic dimensions, whereas in gynecology, TPU is at present widely used for the evaluation of the female pelvic floor, opening new boundaries for the assessment of pelvic floor disorders. The association of volumetric three-dimensional techniques has largely contributed to the remarkable progress that has occurred in the use of TPU. The aim of this paper is to offer an overview of the advantages, challenges and future perspectives of the use of TPU for women’s imaging.

Is obstetric anal sphincter injury a risk factor for levator ani muscle avulsion in vaginal delivery?

OBJECTIVE

To analyze whether women who sustain obstetric anal sphincter injury (OASI) in their first vaginal delivery have a higher incidence of levator ani muscle (LAM) avulsion than do women without OASI.

METHODS

We conducted a prospective observational cohort study of 80 primiparous women who gave birth at our tertiary obstetric unit between September 2011 and July 2013. The women were divided into two groups: women diagnosed with OASI during vaginal delivery (n = 40) and women without OASI (n = 40), matched by mode of delivery and newborn birth weight. Four-dimensional (4D) transperineal ultrasound was performed in all participants at 6-12 months after delivery to assess for integrity or avulsion of the LAM. Ultrasound images were evaluated by two observers who were blinded to group assignment and clinical data. Interobserver agreement was assessed to determine the reproducibility of 4D transperineal ultrasound for diagnosing LAM avulsion.

RESULTS

We found no statistically significant differences between the two groups. The incidence of LAM avulsion was 24.3% in the OASI group and 34.2% in the control group (P = 0.448). Interobserver agreement in the diagnosis of LAM avulsion in the study population using 4D transperineal ultrasound was 89.5%, with a kappa index of 0.76.

CONCLUSIONS

Our findings do not support OASI as a risk factor for LAM avulsion. Prospective studies in larger populations are needed to establish the biomechanical relationships of the pelvic floor structures involved in vaginal delivery. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Forceps delivery is associated with increased risk of pelvic organ prolapse and muscle trauma: a cross-sectional study 16-24 years after first delivery

OBJECTIVES

To study possible associations between mode of delivery and pelvic organ prolapse (POP) and pelvic floor muscle trauma 16-24 years after first delivery and, in particular, to identify differences between forceps and vacuum delivery.

METHODS

This was a cross-sectional study including 608 women who delivered their first child in 1990-1997 and were examined with POP quantification (POP-Q) and pelvic floor ultrasound in 2013-2014. Outcome measures were POP ≥ Stage 2 or previous prolapse surgery, levator avulsion and levator hiatal area on Valsalva. Univariable and multivariable logistic regression analyses and ANCOVA were applied to identify outcome variables associated with mode of delivery.

RESULTS

Comparing forceps to vacuum delivery, the adjusted odds ratios (aOR) were 1.72 (95% CI, 1.06-2.79; P = 0.03) for POP ≥ Stage 2 or previous prolapse surgery and 4.16 (95% CI, 2.28-7.59; P < 0.01) for levator avulsion. Hiatal area on Valsalva was larger, with adjusted mean difference (aMD) of 4.75 cm(2) (95% CI, 2.46-7.03; P < 0.01). Comparing forceps with normal vaginal delivery, the adjusted odds ratio (aOR) was 1.74 (95% CI, 1.12-2.68; P = 0.01) for POP ≥ Stage 2 or surgery and 4.35 (95% CI, 2.56-7.40; P < 0.01) for levator avulsion; hiatal area on Valsalva was larger, with an aMD of 3.84 cm(2) (95% CI, 1.78-5.90; P < 0.01). Comparing Cesarean delivery with normal vaginal delivery, aOR was 0.06 (95% CI, 0.02-0.14; P < 0.01) for POP ≥ Stage 2 or surgery and crude OR was 0.00 (95% CI, 0.00-0.30; P < 0.01) for levator avulsion; hiatal area on Valsalva was smaller, with an aMD of -8.35 cm(2) (95% CI, -10.87 to -5.84; P < 0.01). No differences were found between vacuum and normal vaginal delivery.

CONCLUSIONS

We found that mode of delivery was associated with POP and pelvic floor muscle trauma in women from a general population, 16-24 years after their first delivery. Forceps was associated with significantly more POP, levator avulsion and larger hiatal areas than were vacuum and normal vaginal deliveries. There were no statistically significant differences between vacuum and normal vaginal deliveries. Cesarean delivery was associated with significantly less POP and pelvic floor muscle trauma than were normal or operative vaginal delivery.

Can 3D power Doppler identify levator ani vascularization at its pubic insertion?

INTRODUCTION AND HYPOTHESIS

The levator ani is the most important muscle in the pelvic floor. This pilot study using 3D power Doppler aimed to identify normal vascularization of the puborectalis/pubovisceralis muscle at its insertion in nulliparous and premenopausal women.

METHODS

Forty nulliparous and premenopausal women were evaluated at the Gynecological Unit of a tertiary hospital. All women underwent a translabial ultrasound (US) with 3D power Doppler. Pubic insertion of the puborectalis/pubovisceralis muscle was assessed in the axial plane, and vascularization index (VI), flow index (FI), and vascularization-flow index (VFI) were calculated bilaterally. Volumes were analyzed offline by two independent observers, and interobserver agreement and correlation between variables was calculated.

RESULTS

A high, statistically significant, correlation was found between the three US indices on each side (p < 0.005). No correlation was found between the US index and either of the demographic parameters of body mass index [(BMI), p > 0.241], or age (p > 0.398). The degree of correlation between the same index on the different sides was not statistically significant.

CONCLUSION

Puborectalis/pubovisceralis muscle vascularization at its insertion can be identified using 3D Doppler US, but values differ substantially from those of the contralateral side.

Predicting Birth-Related Levator Ani Tear Severity in Primiparous Women: Evaluating Maternal Recovery from Labor and Delivery (EMRLD Study)

OBJECTIVE

To determine which maternal characteristics or birth events independently predict severity of levator ani muscle (LA) tears at first vaginal birth in a longitudinal/observational investigation in a tertiary care hospital.

SAMPLE

Ninety primiparas with at least one at risk for LA tear inclusion factor at vaginal birth: maternal age ≥ 33 years, second stage ≥ 150 minutes, macrosomia, instrumented delivery, and/or anal sphincter laceration were studied.

METHODS

Magnetic Resonance Imaging (MRI) was obtained early postpartum (mean ± sd 48.9 ± 21.6 days) to identify LA tear. Severity of LA muscle fiber loss was graded on an ordinal scale of: "0" as no loss, "1" as <50% unilateral loss, "2" as ≥50% unilateral or <50% bilateral loss, and "3" as ≥50% bilateral loss. Data were analyzed using proportional odds modeling. Inclusion factors were explored as predictors of LA tear severity and at analysis episiotomy, time spent actively pushing, epidural, and oxytocin were also considered. The main outcome measures of interest included grading of severity of LA muscle fiber loss on an ordinal scale.

RESULTS

Respective counts/percentages of women within each 0 thru 3 ordered category of LA tear severity were: "0" = 58(64%), "1" = 9(10%), "2" = 15(17%), and "3" = 8(9%). Estimates and 95% CI for significant demographic or obstetric univariate predictors of LA tear severity level were age, OR 1.093 (CI 1.012 - 1.180), p = 0.023; and time spent in active pushing, OR 1.089 (CI 1.005 - 1.180), p = 0.038. The other factors considered were not significant. There were too few women with forceps deliveries to analyze. CONCLUSION: In our enriched sample of primiparous women, 26% showed a significant LA tear. Maternal age and time spent actively pushing independently predict LA tear severity.