Prediction of levator ani muscle avulsion by genital tears after vaginal birth-a prospective observational cohort study

A biomechanical perspective on perineal injuries during childbirth

BACKGROUND AND OBJECTIVE

Childbirth trauma is a major health concern that affects millions of women worldwide. Severe degrees of perineal trauma, designated as obstetric anal sphincter injuries (OASIS), and levator ani muscle (LAM) injuries are associated with long-term morbidity. While significant research has been conducted on LAM avulsions, less attention has been given to perineal trauma and OASIS, which affect up to 90% and 11% of vaginal deliveries, respectively. Despite being widely discussed, childbirth trauma remains unpredictable. This work aims to enhance the modeling of the maternal musculature during childbirth, with a particular focus on understanding the mechanisms underlying the often overlooked perineal injuries.

METHODS

A geometrical model of the pelvic floor muscles (PFM) and perineum (including the perineal body, ischiocavernosus, bulbospongiosus, superficial and deep transverse perineal muscles) was created. The muscles were characterized by a transversely isotropic visco-hyperelastic constitutive model. Two simulations of vaginal delivery were conducted with the fetus in the vertex presentation and occipito-anterior position, with and without the perineum.

RESULTS

The simulation that considered the perineum exhibited higher stresses over an extended area of the PFM, which suggests that including additional structures can impact the obtained results. The maximum stretch of the urogenital hiatus was 2.94 and the maximum stress was 23.86 kPa. The perineal body reached a maximum stretch of 1.95, which was more pronounced near the urogenital hiatus, where perineal tears may occur. The external anal sphincter's transverse diameter decreased by 51% and the maximum principal stresses were observed in the area close to the perineal body, where OASIS can occur.

CONCLUSIONS

The present study emphasizes the importance of including most structures involved in vaginal delivery in its biomechanical analysis and represents another step further in the understanding of perineal injuries and OASIS. The superior region of the perineal body and its connection to the urogenital hiatus and anal sphincter have been identified as the most critical regions, highly susceptible to injury.

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.

When does oasis cause de novo pelvic floor dysfunction? role of the surgeon's skills

INTRODUCTION AND HYPOTHESIS

Minorly skilled gynecologists are less likely to repair obstetric anal sphincter injuries (OASIS), and this can lead to higher rate of de novo onset of pelvic floor dysfunction (PFD). The aim of this study was to understand the impact of surgeon skills in OASIS repair on de novo incidence of PFDs.

METHODS

An observational prospective cohort study performed between January 2019 and December 2020. We included 116 women with OASIS. At 6-weeks from delivery, women were divided into two groups in relation to the onset of PFDs. Characteristics were compared; categorical and continuous variables were assessed with chi-squared test and the Mann-Whitney rank-sum test respectively. Factors involved in PFDs development were analysed with explorative univariate analysis; significant (p<0.05) or approaching significance (p≤0.10) variables were included in multivariable analysis.

RESULTS

Seventy-six women (76/116; 65.5%) reported at least one PFD symptom and anal incontinence was the most prevalent (44.73%; 34/76). OASIS management by a skilled gynaecologist resulted protective for PFDs [aOR 0.33 (0.13-0.61)]. Skilled surgeon reported fewer PFDs than less skilled surgeon (4% vs 82.4%; p<0.0001). Operative delivery was more performed (32.5% vs 15.8%; p= 0.03) and severe OASIS resulted more prevalent (60% vs 17.1%; p<0.0001) among women without PDFs, even if these didn't affect the incidence of de novo PFDs [aOR 1.03 (0.23-1.45) and 0.83 (0.13-1.45), respectively].

CONCLUSIONS

Surgeons skilled in OASIS repair resulted the only protective factor for incidence of de novo PFDs in women with OASIS at 6 weeks of follow up. Improvement of training in OASIS repair is necessary.

Associations of Maternal Complaints to Levator Ani Muscle Trauma within 9 Months after Vaginal Birth: A Prospective Observational Cohort Study

Introduction

Pelvic floor trauma in the form of partial or complete avulsions of the levator ani muscle (LAM) affects 6-42% of women after vaginal birth and can cause tremendous long-term morbidity. Many studies assessed morphological pelvic floor trauma after childbirth but lacked to evaluate women's associated short-term complaints. A proper assessment of trauma and subjective complaints after birth could help to assess possible associations between them and their relevance to women's daily life. Therefore, we aimed to assess women's complaints within the first months after birth in association to their LAM trauma.

Materials and Methods

Between 3/2017 and 4/2019, we prospectively evaluated vaginal births of 212 primiparous women with singletons in vertex presentation ≥ 36 + 0 gestational weeks for levator ani muscle (LAM) trauma by translabial ultrasound, for pelvic organ prolapse by clinical examination, and for urogynecological complaints using questionnaires 1-4 days (P1), 6-10 weeks (P2), and 6-9 months (P3) after birth. The questionnaires were self-designed but oriented to and modified from validated questionnaires. Women's complaints were evaluated for P1-P3 according to their LAM trauma state.

Results

At P1, 67% of women showed an intact LAM, whereas 14.6% presented a hematoma, 6.6% a partial avulsion (PAV), and 11.8% a complete avulsion (CAV). At P2, 75.9% showed an intact LAM, 9.9% a PAV, and 14.2% a CAV. At P3, 72.9% of women with a LAM trauma in P1 and/or P2 were assessed with 21.6% being intact and 39.2% having a PAV and CAV, respectively. Obstetrical and baseline characteristics differed slightly between the groups. When comparing the time before and during pregnancy with the time after childbirth, birth itself affected women's complaints in all LAM state groups, but the presence of a LAM trauma, especially a CAV, had more negative effects.

Conclusions

Vaginal birth changes the anatomical structure of the maternal birth canal and genital tract, and it alters women's perceptions and body function. In our study, LAM trauma did not change these effects tremendously within the first months. Therefore, other maternal, fetal, and obstetrical factors need consideration for the explanation of maternal complaints, in addition to long-term effects of trauma and dysfunction of the LAM and other birth canal structures.

Vaginal birth after Cesarean section and levator ani avulsion: a case-control study

OBJECTIVE

The aim of this study was to explore the risk of levator ani muscle (LAM) avulsion and enlargement of the levator hiatus following vaginal birth after Cesarean section (VBAC) in comparison with vaginal delivery in primiparous women.

METHODS

In this two-center observational case-control study, we identified all women who had a term VBAC for their second delivery at the Departments of Obstetrics and Gynecology at the Faculty of Medicine in Pilsen and the 1^st Faculty of Medicine in Prague, Charles University, Czech Republic, between 2012 and 2016. Women with a repeat VBAC, preterm birth or stillbirth were excluded from the study. As a control group, we enrolled a cohort of primiparous women who delivered vaginally during the study period. To increase our control sample, we also invited all primiparous women who delivered vaginally in both participating units between May and June 2019 to participate. All participants were invited for a four-dimensional pelvic floor ultrasound scan to assess LAM trauma. LAM avulsion and the area of the levator hiatus were assessed offline from the stored pelvic floor volumes obtained at rest, during maximum contraction and during Valsalva maneuver. The laterality of the avulsion was also noted. The cohorts were then compared using the χ² test and Wilcoxon's two-sample test according to the normality of the distribution. P < 0.05 was considered statistically significant. Multivariate regression analysis, controlling for age and body mass index (BMI), was also performed.

RESULTS

A total of 356 women had a VBAC for their second delivery during the study period. Of these, 152 (42.7%) attended the ultrasound examination and full data were available for statistical analysis for 141 women. The control group comprised 113 primiparous women. A significant difference was observed between the VBAC group and the control group in age (32.7 vs 30.1 years; P < 0.05), BMI (28.4 vs 27.4 kg/m² ; P < 0.05) and duration of the first and second stages of labor (293.1 vs 345.9 min; P < 0.05 and 27.6 vs 35.3 min; P < 0.05, respectively) at the time of the index birth. The LAM avulsion rate was significantly higher in the VBAC compared with the control group (32.6% vs 18.6%; P = 0.01). The difference between the groups was observed predominantly in the rate of unilateral avulsion and remained significant after controlling for age and BMI (adjusted odds ratio 2.061 (95% CI, 1.103-3.852)). There was no statistically significant difference in the area of the levator hiatus at rest (12.0 vs 12.6 cm² ; P = 0.28) or on maximum Valsalva maneuver (18.6 vs 18.7 cm² ; P = 0.55) between the VBAC and control groups. The incidence of levator hiatal ballooning was comparable between the groups (17.7% and 18.6%; P = 0.86).

CONCLUSIONS

VBAC is associated with a significantly higher rate of LAM avulsion than is vaginal birth in nulliparous women. The difference was significant even after controlling for age and BMI. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

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.