Validation of a built-in software in automatically reconstructing the tomographic images of the levator ani muscle

INTRODUCTION AND HYPOTHESIS

Transperineal ultrasound (TPUS) is an effective tool for evaluating the integrity of the levator ani muscle (LAM). Several operating steps are required to obtain the standard multi-slice image of the LAM, which is experience dependent and time consuming. This study was aimed at evaluating the feasibility and reproducibility of the built-in software, Smart-pelvic™, in reconstructing standard tomographic images of LAM from 3D/4D TPUS volumes.

METHODS

This study was conducted at a tertiary teaching hospital, enrolling women who underwent TPUS. Tomographic images of the LAM were automatically reconstructed by Smart-pelvicTM and rated by two experienced observers as standard or nonstandard. The anteroposterior diameter (APD) of the levator hiatus was also measured on the mid-sagittal plane of the automatically and manually reconstructed images. The APD measurements of each approach were compared using Bland-Altman plots, and interclass correlation coefficient (ICC) was used to evaluate intra- and inter-observer reproducibility. Meanwhile, the time taken for the reconstruction process of both methods was also recorded.

RESULTS

The ultrasound volume of a total of 104 patients were included in this study. Using Smart-pelvicTM, the overall success rate of the tomographic image reconstruction was 98%. Regarding measurements of APD, the ICC between the automatic and manual reconstruction methods was 0.99 (0.98, 0.99). The average time taken for reconstruction per case was 2.65 ± 0.52 s and 22.08 ± 3.45 s, respectively.

CONCLUSIONS

Using Smart-pelvicTM to reconstruct tomographic images of LAM is feasible, and it can promote TPUS by reducing operator dependence and improving examination efficiency in a clinical setting.

Evaluation of levator ani muscle elasticity after vaginal delivery and cesarean section using shear wave elastography

PURPOSE

The risk of pelvic floor muscle injury is commonly considered to be higher in vaginal than in cesarean delivery. This study aimed to compare levator ani muscle (LAM) elasticity after vaginal and cesarean delivery using shear wave elastography (SWE).

METHODS

Postpartum women who underwent a single SWE evaluation 1 month after their first delivery were divided into vaginal and cesarean delivery groups. The elastic moduli of both sides of the LAM were measured in a horizontal section and compared between the groups. In addition, a subgroup analysis was performed to compare LAM elasticity according to the delivery method within the vaginal delivery group-normal vaginal delivery, episiotomy, and operative vaginal delivery.

RESULTS

Sixty-two women were included (vaginal delivery, n = 47; elective cesarean section, n = 15). Multiple regression analysis revealed that the LAM elastic modulus was significantly lower in the vaginal delivery group than in the cesarean delivery group (right LAM: 44.2 vs. 72.7 kPa, p = 0.0036; left LAM 40.4 vs. 82.7 kPa, p < 0.0001). In the subgroup analysis, the right LAM elastic modulus was significantly lower in the operative vaginal delivery subgroup than in the normal vaginal delivery subgroup (p = 0.0131). However, there was no significant difference in the left LAM elastic modulus between the three subgroups.

CONCLUSION

LAM elasticity was significantly lower after vaginal delivery than after cesarean delivery. Furthermore, the elasticity of the right LAM was lower after operative vaginal delivery than after normal vaginal delivery. SWE has the potential to provide an objective quantitative assessment of postpartum pelvic floor muscle recovery.

Evaluating changes in the strength of the levator ani muscle after vaginal delivery using T2-parameter mapping

OBJECTIVE

To evaluate pelvic floor muscle injury in patients with levator ani muscle (LAM) weakness after vaginal delivery using T2-parameter mapping.

MATERIALS AND METHODS

40 parturients (patient group) and 25 nonparturients (healthy control group) were enrolled in the study. The LAM weakness group had a Modified Oxford Grading System (MOGS) grade of less than 3 after vaginal delivery. All participants underwent pelvic magnetic resonance imaging (MRI) scans, including T2 and T2* mapping, on which the main branches of the LAM, the puborectalis and iliococcygeus, were evaluated. The differences in T2 and T2* values in the puborectalis and iliococcygeus between patients with LAM weakness and controls were analyzed using an independent samples t test or a Mann-Whitney U test.

RESULTS

For both the right and left iliococcygeus, the T2* values of the patient group were lower than those of the control group (P = 0.002 and 0.008, respectively), while no significant difference was observed in the T2 values between the groups (P = 0.45 and 0.69, respectively). For both the right and left puborectalis, no significant differences in the T2* (P = 0.25 and P = 0.25, respectively) or T2 values (P = 0.38 and 0.43, respectively) were observed between the patient and control groups.

CONCLUSION

T2* mapping as a quantitative measurement is an effective imaging tool to assess LAM injury in women after vaginal delivery. The iliococcygeus was more susceptible to vaginal delivery damage than the puborectalis, and pelvic floor dysfunction may be mainly driven by iliococcygeus injury.

Appearance of levator ani muscle subdivision defects on level III vaginal support structures in women with and without pelvic organ prolapse: an MRI study

INTRODUCTION AND HYPOTHESIS

Injury of the levator ani muscle (LAM) is a significant risk factor for pelvic organ prolapse (POP). The puborectalis (PRM) and pubovisceral (PVM) subdivisions are level III vaginal support structures. The null hypothesis was that there is no significant difference in patterns of LAM subdivisions in healthy nulliparous women. Secondarily, we evaluated the presence of different LAM injury in a POP-symptomatic cohort.

METHODS

This retrospective magnetic resonance imaging study included: 64 nulligravidae without any pelvic floor dysfunction (PFD) and 526 women of various parity with symptomatic POP. Primary outcome was PVM and PRM morphology on the axial planes: the attachment site on the pubic bone, and the visible separation/border between the PVM and PRM. The attachment was scored as "normal" or "abnormal". The "abnormal" attachment was divided in two types: "type I"-loss of the muscle substance, but preservation of the overall muscle architecture-and "type II"-muscle detachment from the pubic bone.

RESULTS

The puboanal muscle (PAM) subdivision was evaluated as a representative part of the PVM. The PAM and PRM attachments and separation were distinguished in all asymptomatic nulliparae. PAM and PRM attachments did not significantly differ. POP group characteristics were parity 1.9 ± 0.8, instrumental delivery 5.6%, hysterectomy or POP surgery 60%, all Pelvic Organ Prolapse Quantification (POP-Q) stages, LAM defect 77.6% (PRM: 77.1%; PAM: 51.3%). Type I injuries were more frequent (PRM 54.7%; PAM 53.9%) compared with type II (PRM 29.4%; PAM 42.1%).

CONCLUSIONS

A LAM defect was present in 77.6% of women with symptomatic POP. In PRM and PAM subdivisions type I injury was more frequent than type II.

Comparison of the anterior pelvis and levator ani muscle on MRI in women with and without anterior pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

The objective was to compare the differences in pelvic and levator ani muscle diameters in women with and without anterior pelvic organ prolapse.

METHODS

Three groups were included, including 50 nulliparous women (nulliparous group), 50 women with stage III-IV anterior vaginal prolapse (prolapse group), and 50 women of the same age as the prolapse group but without prolapse (nonprolapse control group). The ischial interspinous diameter (ISD), anterior pelvic area (APA), levator defect score (LDS), levator ani hiatus width (LH-W), H-line, M-line, levator ani plate length, levator ani plate angle, and cervix length (CL) were measured.

RESULTS

There were no significant differences in ISD (10.6±0.8 vs 10.6±0.9 cm), LH-W (3.0±0.4 vs 3.3±0.4 cm), or CL (2.9±0.6 vs 3.0±0.5 cm) between the nulliparous group and the nonprolapse control group (p>0.05). However, there were significant differences between them and the prolapsed group (11.2±0.6 cm, 3.6±0.4 cm, 4.2±1.5 cm; p<0.05). There were no significant differences in LDS (0.70±0.61 vs 0.70±0.65) or APA (58.4±8.4 vs 60.1±7.4 cm2) between the nonprolapse control group and the prolapse group (p>0.05), but they were significantly different from those of the nulliparous group (0.08±0.34, 55.1±6.0 cm2) (p<0.05). The area under the receiver-operating characteristic curve for the ISD of nonprolapse control and prolapse groups was 0.713, and the cutoff value was 10.95 cm.

CONCLUSIONS

The levator ani hiatus width and cervix length were larger in patients with anterior vaginal prolapse than in those without prolapse. An ischial ISD greater than 10.95 cm was associated with prolapse.

Factors involved in changes in the levator ani during pregnancy

INTRODUCTION AND HYPOTHESIS

Levator ani muscle (LAM) dimensions increase during pregnancy to allow the delivery of the fetus. The objective was to investigate which factors are involved in LAM modifications during pregnancy.

METHODS

A prospective longitudinal observational study was conducted between July 2015 and March 2018. Ninety-nine nulliparous pregnant women were included. Data on the physical examination, 4D transperineal ultrasound and hormonal concentrations (progesterone, oestradiol and relaxin) were collected during the first and third trimesters.

RESULTS

We found higher hiatal dimensions at the beginning of pregnancy than in other studies with nonpregnant women. Increases in the levator ani hiatal (LH) dimensions were observed at contraction (1.01 ±1.96 cm2), rest (0.82 ± 2.51 cm2) and on Valsalva (2.36 ± 3.64 cm2) throughout pregnancy. The distensibility in the third trimester was higher than in the first trimester (5.79 vs 4.24 cm2; p=0); however, the contractility was lower (-3.32 vs -3.5 cm2; p=0.04). Women with lower scores on the Modified Oxford Grading Scale in the third trimester presented with lower contractility in the LAM. A larger LH at the end of pregnancy was associated with age and body mass index. Eleven women developed ballooning during pregnancy; in these women, relaxin was higher in both trimesters than in women without ballooning, but these results were not statistically significant. The linear models to predict third-trimester Valsalva LH, distensibility and contractility were not conclusive and did not show any factors to predict LAM modifications during pregnancy.

CONCLUSIONS

Hormones could play a role in modifying the muscle properties of LAM from the beginning of pregnancy, but we did not find an association between LAM measurements and hormone concentration in this study.

Multimodal measurements of levator bowl volume in nulligravid asymptomatic women: endovaginal ultrasound versus MRI

INTRODUCTION AND HYPOTHESIS

Measurements of levator bowl volume using advanced imaging, may be predictive of pelvic floor muscle function. The aim of this study was to compare the volume of the levator bowl using both magnetic resonance imaging (MRI) and endovaginal ultrasound (EVU) of healthy asymptomatic women.

METHODS

All participants underwent a comprehensive interview including completion of the Pelvic Floor Distress Inventory Questionnaire-20 questionnaire, pelvic examination with a pelvic organ prolapse quantification evaluation, MRI, and EVU. The pelvic floor was segmented using Slicer and the MRI segmentations were trimmed using two methods: soft-tissue landmarks and the field of view (FOV) of the ultrasound volume. The levator bowl volume of the 3D segmented shapes was measured using Blender's 3D printing toolkit. Normality was tested using the Shapiro-Wilks test and comparisons were made using self-paired t tests.

RESULTS

The final analysis included 19 patients. Levator bowl volume measured via MRI was larger than that measured in EVU (46.1 ± 7.9 cm3 vs 27.4 ± 5.9 cm3, p<0.001). Reducing the FOV of the MRI to that of EVU caused the MRI volume to be much closer to the EVU volume (35.5 ± 3.3 cm3 vs 27.4 ± 5.9 cm3, p<0.001); however, it remained significantly larger.

CONCLUSION

Levator bowl volume measured using MRI was larger than that measured using EVU no matter the method of delineation of the levator muscles. Although EVU is safe, cheap, and easy to perform, it captures a smaller volume of levator bowel than MRI.

Creation of the biomechanical finite element model of female pelvic floor supporting structure based on thin-sectional high-resolution anatomical images

PURPOSE

The main purpose of this study is to obtain a finite element biomechanical model that accurately mimics pelvic organ prolapse in women, to study pelvic floor supporting structures' biomechanical properties and function. We used thin-sectional high-resolution anatomical images (Chinese Visible Human, CVH) to reconstruct a detailed three-dimensional (3D) biomechanical finite element model of the female pelvic floor supporting structure including cardinal ligament, uterosacral ligament, levator ani muscle (LAM) and perianal body. The Valsalva maneuver was simulated by loading the uterus and bladder with a pressure increasing from 0 to 10 kPa. The stress, strain and displacement of supporting structures were calculated. The cardinal ligament, the uterosacral ligament and the LAM were stressed greatly when the uterus moved downward, and the maximum stress could reach 0.267 MPa, 1.51 MPa and 0.065 MPa respectively, and the maximum strain could reach 0.154, 0.16, 0.265, and the maximum displacement could reach 1.786 cm, 1.946 cm and 0.567 cm. Displacement of the perineal body also occurred, and its stress, strain and displacement were 0.092 MPa, 0.381, 0.73 cm. The stress, strain and displacement of the supporting structure around the urethra were 0.339 MPa, 0.169, 1.491 cm. Our model based on CVH has more detailed anatomical structures, which is superior to that based on MRI. Our simulation results were consistent with previous findings, which verified the unbalance of abdominal pressure and pelvic floor supporting structures will lead to POP, which provide a theoretical basis for pelvic floor anatomy and function as well as obstetrical surgery.

A review of levator ani avulsion after childbirth: Incidence, imaging and management

Key Content • Levator ani muscle (LAM) avulsion injury occurs occultly during childbirth, most commonly during operative vaginal deliveries. • Injuries of levator ani have long term sequelae for pelvic floor health. As life expectancy increases the burden of disease upon urogynaecology services will need to be considered. • Diagnosis of this condition can be difficult as there is no agreed 'gold standard' imaging modality. • There is no consensus regarding surgical management of LAM avulsion. Learning objectives • Review anatomy and function of levator ani muscle • Identify the risk factors for levator ani avulsion injury • Role of imaging to appropriately identify LAM injury and current management options including appropriate follow up • Management of subsequent pregnancy following LAM avulsion Ethical issues • Is there value to the patient in diagnosing levator ani avulsion when there is no recommended treatment for these injuries?

Usefulness of transperineal shear wave elastography of levator ani muscle in women with stress urinary incontinence

This study aimed to quantitatively assess the quality of levator ani muscle (LAM) using shear wave elastography (SWE) and to evaluate the association between the elasticity of LAM and stress urinary incontinence (SUI). The study population included 32 women with SUI and 34 women with normal pelvic support. The thickness of LAM, bladder neck descent (BND), and urethral funneling (UF) were assessed by transperineal ultrasound. LAM elasticity was measured by SWE at rest and during the maximal Valsalva maneuver. Age, menopause, BND, and UF showed a positive correlation with SUI. There was no significant between-group difference in the elastic modulus values of LAM at rest. The thickness of LAM in women with SUI was greater than that in control group at rest and during the maximal Valsalva maneuver (P < 0.001). The elastic modulus values of E_max and E_mean were significantly increased from rest to the maximal Valsalva maneuver in all participants (56.24 vs 82.43 kPa and 47.92 vs 72.37 kPa, P < 0.001). The change of these variables from rest to the maximal Valsalva maneuver in the control group was more obvious than that in the SUI group (34.09 vs 17.87 kPa and 31.55 vs 16.82 kPa, P < 0.05). The elasticity of LAM, as quantified by SWE, may potentially be used as an index for predicting SUI.

Effect of prolonged second stage of labor on pelvic floor function: A prospective cohort study

INTRODUCTION AND HYPOTHESIS

To evaluate the effect of the second stage of labor (SSL) lasting > 2 h on pelvic floor function.

METHODS

This single-center prospective cohort study included primiparous women with SSL > 2 h treated at Tongji Hospital between January 2018 and December 2019 (case group). A matched group of women with similar newborn weight and SSL < 2 h were recruited simultaneously (control group). Stress urinary incontinence (SUI) and pelvic floor muscle (PFM) characteristics were measured at 6 weeks, 6 months, and finally 1 year postpartum.

RESULTS

A total of 63 pairs of primiparous women completed 1-year follow-up. The incidence of SUI in the case group was significantly higher than that in the control group at 6 weeks postpartum (P = 0.020); however, the differences were not significant at 1 year postpartum (P=1.00). PFM endurance was significantly lower in the case group at 6 weeks (P = 0.000), 6 months (P = 0.000), and 1 year (P = 0.011) after childbirth. There was no difference in PFM strength between the two groups. The maximal voluntary contraction (MVC) of PFM was significantly lower in the case group at 6 weeks postpartum (P = 0.007), but the differences were not significant at 1 year postpartum (P = 0.197). PFM endurance and MVC were higher at 1 year than at 6 weeks postpartum in both groups.

CONCLUSIONS

The SSL > 2 h increased the incidence of SUI at 6 weeks postpartum and decreased PFM endurance for 1 year.

Measuring morphological parameters of the pelvic diaphragm muscles using computed tomography in healthy dogs

Evaluation of pelvic diaphragm muscles in dogs merits clinical attention because of the anatomical importance and their involvement in perineal hernia. This study aimed to evaluate the normal pelvic diaphragm muscles (levator ani and coccygeus muscles) using the computed tomography (CT) scan. For this purpose, 10 male and 10 female clinically normal, adult intact mixed-breed dogs weighing 15.00 to 20.00 kg were selected randomly. All animals underwent CT examination under general anesthesia and positioned in sternal recumbency. All the CT images were taken and reconstructed with a same protocol. The measurements of the pelvic diaphragm muscles were performed based on the presented guideline to the observer. The results were presented descriptively. The mean lengths of the coccygeus muscle in CT images were evaluated 4.60 cm for males and 4.30 cm for females. The mean lengths of levator ani muscle in CT images were measured 4.90 cm in males and 4.50 cm in females. In conclusion, the results of the present study can be beneficial to clinicians and researchers for further evaluation of the supporting muscles in pelvic cavity and underlying anatomical changes in perineal hernia in dogs.

Levator plate descent angle in pelvic floor disorders

BACKGROUND

The levator plate descent angle (LPDA) quantifies the levator plate position with reference to the pubic bone and perineal body at rest. Unfortunately, research on this notable new parameter is lacking, but it is clear that levator ani deficiency (LAD) will undermine the fundamental role of the levator ani muscle (LAM) in organ support. The aim of this study was to establish the relationship between the LPDA and LAD in patients with pelvic floor disorders.

METHODS

This retrospective study was conducted at Seoul Songdo Hospital, Korea between August 2019 and August 2020 on women with symptoms of pelvic floor disorder such as urinary incontinence, constipation, and fecal incontinence. In all cases, three-dimensional pelvic floor ultrasound was performed for LAD scoring, minimal levator hiatus, and LPDA evaluation. We evaluated LAD using a scoring system that graded levator injury according to the insertion point of each subdivision scored unilaterally. For the entire LAM group, a cumulative LAD score that ranged between 0 and 18 was possible. Scores were categorized as mild (0-6 points), moderate (7-12 points), and severe (13-18 points) deficiency RESULTS: A total of 93 patients were included in the study (mean age 65.89 ± 11.12 [range, 34-86] years). Thirteen participants had mild LAD scores (14.0%), 42 had moderate LAD scores (45.2%), and 38 had severe LAD scores (40.9%). There was a significant difference in mean age (59.23 ± 12.55 years vs. 64.43 ± 10.03 vs. 69.79 ± 10.55 years, p = 0.005) and mean parity (1.85 ± 0.90 vs 2.48 ± 1.15 vs 2.76 ± 1.10, p = 0.038) of patients between groups. There was also a significant difference in the mean Wexner incontinence score (7.14 ± 3.63 vs 7.24 ± 5.76 vs 11.41 ± 5.54, p = 0.028) and in the mean fecal incontinence quality of life (FIQOL) score (12.91 ± 3.11 vs 14.10 ± 3.87 vs 10.41 ± 3.65, p = 0.014). The mean value of the LPDA in the group with mild LAD scores was 14.65° (SD ± 3.54) and in the group with moderate LAD scores was 9.66° (SD ± 3.36). In the group with severe LAD scores, the mean LPDA was 1.83° (SD ± 4.71). The mean value for minimal levator hiatus (MLH) area in the mild LAD score group was 14.16cm² (SD ± 2.72), that in the moderate LAD score group was 15.82cm² (SD ± 2.30), and that in the severe LAD score group was 17.99cm² (SD ± 2.81). There were significant differences between the three groups both in decreasing LPDA (p < 0.001) and increasing MLH (p < 0.001). There was a negative correlation between the LAD score and LPDA and the Pearson correlation coefficient was -0.528 (moderate correlation). There was a positive correlation between the LAD score and MLH, and the Pearson correlation coefficient was 0.303 (weak correlation).

CONCLUSIONS

The LAD score and LPDA have a moderate negative correlation. In patients with severe pelvic floor symptoms and extensive LAM injury, high LAD scores and low LPDA results were confirmed. In the treatment of patients with pelvic floor disorders, the LPDA seems to be a very useful parameter in determining the severity of structural defects.

Appearance of the levator ani muscle subdivisions on 3D transperineal ultrasound

BACKGROUND

The levator ani muscle (LAM) consists of different subdivisions, which play a specific role in the pelvic floor mechanics. The aim of this study is to identify and describe the appearance of these subdivisions on 3-Dimensional (3D) transperineal ultrasound (TPUS). To do so, a study designed in three phases was performed in which twenty 3D TPUS scans of vaginally nulliparous women were assessed. The first phase was aimed at getting acquainted with the anatomy of the LAM subdivisions and its appearance on TPUS: relevant literature was consulted, and the TPUS scan of one patient was analyzed to identify the puborectal, iliococcygeal, puboperineal, pubovaginal, and puboanal muscle. In the second phase, the five LAM subdivisions and the pubic bone and external sphincter, used as reference structures, were manually segmented in volume data obtained from five nulliparous women at rest. In the third phase, intra- and inter-observer reproducibility were assessed on twenty TPUS scans by measuring the Dice Similarity Index (DSI).

RESULTS

The mean inter-observer and median intra-observer DSI values (with interquartile range) were: puborectal 0.83 (0.13)/0.83 (0.10), puboanal 0.70 (0.16)/0.79 (0.09), iliococcygeal 0.73 (0.14)/0.79 (0.10), puboperineal 0.63 (0.25)/0.75 (0.22), pubovaginal muscle 0.62 (0.22)/0.71 (0.16), and the external sphincter 0.81 (0.12)/0.89 (0.03).

CONCLUSION

Our results show that the LAM subdivisions of nulliparous women can be reproducibly identified on 3D TPUS data.

Association between elastography findings of the levator ani and stress urinary incontinence

PURPOSE

To investigate the elasticity of the levator ani musle (LAM) with the patients suffering from stress urinary incontinence (SUI) by transperineal elastography.

METHODS

Conventional transperineal ultrasound and elastography were performed in the patients with SUI on quiescent condition and maximal Valsalva. Transperineal ultrasound and elastography were repeated after Kegel exercises. The scoring system and strain ratio (SR) values were recorded and analyzed.

RESULTS

After Kegel exercises, the ratio of subjective improvement or cure was 81 % (102/126). Mean elasticity score (ES) and SR of LAM were significantly higher than the value before on maximal Valsalva, respectively. Mean ES and SR of LAM after Kegel exercises were similar with the value before on quiescent condition, respectively.

CONCLUSION

The improvement of SUI was associated with the stiffer LAM assessed by elastography. Women with SUI who have softer LAM were more likely to have symptoms of SUI and Kegel exercise could strengthen the stiffness of LAM.

BRIEF SUMMARY

The improvement of SUI was associated with the stiffer LAM assessed by elastography.

The usual suspect: cross-sectional study of fundal pressure at second stage of delivery and the association with pelvic floor damage

INTRODUCTION AND HYPOTHESIS

Uterine fundal pressure is applied to accelerate birth by increasing the expulsive force of the uterus in the second stage of delivery. The aim of the study was to evaluate the effect of using uterine fundal pressure during the second stage of delivery on the rate of pelvic floor damage among primiparous women using three-dimensional transperineal ultrasonography.

METHODS

The women were divided into two groups: the fundal pressure group included women where the fundal pressure maneuver was applied (n = 39); the control group included women who delivered spontaneously without fundal pressure (n = 47). 3D-TPU was performed within 48 h of delivery, and LAM biometry, LAM defect and loss of tenting were determined.

RESULTS

Anteroposterior hiatal dimensions on resting, maximal Valsalva and maximal PFMC were found to be higher in the fundal pressure group (p < 0.0001, p = 0.008, p = 0.007, respectively). The mean hiatal area at rest was larger in the fundal pressure group than in the control group (p = 0.04). The rate of LAM defect was significantly higher in the fundal pressure group (p = 0.001). The rate of loss of tenting was significantly higher in the fundal pressure group (p < 0.0001). According to multivariate regression models, the fundal pressure was the only independent factor associated with LAM defect (OR = 5.63; 95% CI = 12.01-15.74) and loss of tenting (OR = 8.74; 95% CI = 2.89-26.43).

CONCLUSIONS

Fundal pressure during the second stage of delivery is associated with a higher risk of LAM defect and loss of anterior vaginal wall support.

CLINICAL TRIAL REGISTRATION

NCT03752879.

Change in levator ani muscle stiffness and active force during pregnancy and post-partum

INTRODUCTION AND HYPOTHESIS

It is assumed changes occur to the biomechanics and viscoelastic response of the levator ani muscle during pregnancy; however, there is limited evidence of this. This study used instrumentation and clinical measures to determine the stiffness and active force capacity of levator ani muscle during pregnancy and post-partum, investigated any associations with delivery outcomes, and explored the biomechanical properties associated with symptoms of pelvic floor dysfunction.

METHODS

This was a prospective observational study, with nulliparous women with a singleton low-risk pregnancy. Data were collected at two stages during pregnancy and post-partum. Measurements included the Australian Pelvic Floor Questionnaire, palpation of active force, and elastometry measurements. Post-partum, 3D/4D ultrasound measurements were included. Repeated measures ANOVAs, pairwise comparisons, Pearson correlation coefficients, and Student's t-tests were used as appropriate.

RESULTS

Fifty-nine women took part in the study. Active force was significantly different over the pregnancy and post-partum, measured with instrumentation (p = 0.002) and palpation (p = 0.006 right, p = 0.029 left). There was no significant change in muscle stiffness during pregnancy. Post-partum muscle stiffness was significantly different between women who gave birth vaginally vs. caesarean section (p = 0.002). Post-partum there were differences in levator hiatal area, symptoms of bladder dysfunction, prolapse symptoms, and sexual dysfunction symptoms.

CONCLUSIONS

Active force of the levator ani muscle was significantly reduced during pregnancy and in the post-partum period, while muscle stiffness reduced only in those who had vaginal deliveries.

In vivo assessment of the elastic properties of women's pelvic floor during pregnancy using shear wave elastography: design and protocol of the ELASTOPELV study

Background

Animal studies have reported an increase in pelvic floor muscle stiffness during pregnancy, which might be a protective process against perineal trauma at delivery. Our main objective is to describe the changes in the elastic properties of the pelvic floor muscles (levator ani, external anal sphincter) during human pregnancy using shear wave elastography (SWE) technology. Secondary objectives are as follows: i) to look for specific changes of the pelvic floor muscles compared to peripheral muscles; ii) to determine whether an association between the elastic properties of the levator ani and perineal clinical and B-mode ultrasound measures exists; and iii) to provide explorative data about an association between pelvic floor muscle characteristics and the risk of perineal tears.

Methods

Our prospective monocentric study will involve three visits (14–18, 24–28, and 34–38 weeks of pregnancy) and include nulliparous women older than 18 years, with a normal pregnancy and a body mass index (BMI) lower than 35 kg.m^− 2. Each visit will consist of a clinical pelvic floor assessment (using the Pelvic Organ Prolapse Quantification system), an ultrasound perineal measure of the anteroposterior hiatal diameter and SWE assessment of the levator ani and the external anal sphincter muscles (at rest, during the Valsalva maneuver and during pelvic floor contraction), and SWE assessment of both the biceps brachii and the gastrocnemius medialis (at rest, extension and contraction). We will collect data about the mode of delivery and the occurrence of perineal tears. We will investigate changes in continuous variables collected using the Friedman test. We will look for an association between the elastic properties of the levator ani muscle and clinical / ultrasound measures using a Spearman test at each trimester. We will investigate the association between the elastic properties of the pelvic floor muscles and perineal tear occurrence using a multivariate analysis with logistic regression.

Discussion

This study will provide original in vivo human data about the biomechanical changes of pregnant women’s pelvic floor. The results may lead to an individualized risk assessment of perineal trauma at childbirth.

Trial registration

This study was registered on https://clinicaltrials.gov on July 26, 2018 (NCT03602196).

Postpartum sexual function; the importance of the levator ani muscle

Introduction and hypothesis

Pelvic floor muscle function plays an important role in female sexual functioning. Smaller genital hiatal dimensions have been associated with sexual dysfunction, mainly dyspareunia. On the other hand, trauma of the levator ani muscle sustained during childbirth is associated with increased genital hiatus, which potentially can affect sexual functioning by causing vaginal laxity. This study aims to determine the association between levator hiatal dimensions and female sexual dysfunction after first vaginal delivery.

Methods

This is a secondary analysis of a prospective observational study. Two hundred four women who had a first, spontaneous vaginal delivery at term between 2012 and 2015 were recruited at a minimum of 6 months postpartum. Thirteen pregnant women were excluded. We analyzed the association of total PISQ-12 score, as well as individual sexual complaints (desire, arousal, orgasm and dyspareunia), with levator hiatal dimensions at rest, with maximum Valsalva and during pelvic floor muscle contraction as measured by 4D transperineal ultrasound. Statistical analysis was performed using linear regression analysis and Mann-Whitney U test.

Results

One hundred ninety-one women were evaluated at a median of 11 months postpartum. There was no significant association between total PISQ-12 score and levator hiatal dimensions. Looking at individual sexual complaints, women with dyspareunia had significantly smaller levator hiatal area and anterior-posterior diameter on maximum Valsalva. By using multivariate logistic regression analysis however we found dyspareunia was not independently associated with levator hiatal dimensions.

Conclusions

After first vaginal delivery sexual dysfunction is not associated with levator hiatal dimensions as measured by 4D transperineal ultrasound.

Various significant connections of the male pelvic floor muscles with special reference to the anal and urethral sphincter muscles

The male pelvic floor is a complex structure formed by several muscles. The levator ani muscle and the perineal muscles are important components of the pelvic floor. The perineal muscles comprise the external anal sphincter, bulbospongiosus, superficial transverse perineal muscles, and ischiocavernosus. Although the connections of the muscles of the pelvic floor have been reported recently, the anatomical details of each muscle remain unclear. In this study, we examined the male pelvic floor to clarify the connection between the muscles related to function. Fifteen male pelvises were used for microscopic dissection, and three male pelvises were used for histological examination. On the lateral aspect, the perineal muscles were connected to each other. Bundles of the levator ani muscle extended to connect to the perineal muscles. In addition, the extended muscle bundle from the levator ani muscle and the perineal muscles surround the external urethral sphincter. On the medial aspect, the levator ani muscle and the external anal sphincter form the anterior and posterior muscular slings of the anal canal. The connection between the perineal muscles and levator ani muscle indicates a possible close relationship between the functions of the urethra and anus.

Association between Magnetic Resonance Imaging Findings of the Pelvic Floor and de novo Stress Urinary Incontinence after Vaginal Delivery

Objective

The study aimed to evaluate the contributions of levator ani muscle (LAM) injury, vesical neck movement, urethral length and mobility, and urethral sphincter dysfunction observed on magnetic resonance imaging (MRI) towards stress urinary incontinence (SUI) after vaginal delivery.

Materials and Methods

Fifty primiparous women after 6 months of delivery (15 with SUI and 35 without) and 35 nulliparous as continent controls underwent MRI at rest and Valsalva maneuver. A published levator ani scoring system was used to characterize morphological changes of LAM. The severity of the injury was divided into three categories as none, minor, and major. A series of common parameters including levator plate angle, iliococcygeal angle, and levator hiatus were used to describe the functional conditions of LAM. Urethral mobility was defined based on the rotation of the urethra between Valsalva and rest status. Vesical neck movement was evaluated by its distance to the pubococcygeal line. Urethral sphincter dysfunction was defined as the widening of the proximal urethra and/or funneling at the urethrovesical junction during Valsalva.

Results

Primiparous incontinent (PI) women had additional major levator ani defects (33.3% vs. 17.1%) while less minor defects (0.7% vs. 31.4%) than primiparous continent (PC) women. Vesical neck downward movement in PI women was more obvious than PC women (28.5 mm vs. 24.2 mm, p = 0.006). Urethral mobility was more active in primiparous women than in nulliparous continent controls (57.4 vs. 52.4), whereas no difference was observed on urethral mobility in the primiparous group (p = 0.25). Urethral sphincter dysfunction and funneling were present in 80% of PI women versus 22.9% in PC women (p < 0.001).

Conclusion

The MRI findings revealed that de novo SUI was associated with major LAM injury, vesical neck downward movement as well as urethral sphincter dysfunction. Vesical neck funneling on sagittal images can be treated as a valuable predictor for SUI. The intervention for the PI should focus on the elevation of vesical neck, rehabilitation of LAM as well as recovery of the urethral sphincter muscle.

Measurement the thickness of the transverse abdominal muscle in different tasks

[Purpose] This study examined the measurement of the thickness of the transverse abdominal muscle in different tasks. [Subjects and Methods] The subjects were eleven healthy adult females. Thicknesses of transverse abdominal muscle were measured in seven tasks in the supine position. The tasks were: 1) Resting state, 2) Maximal contraction of transverse abdominal muscle, 3) Maximal contraction of levator ani muscle, 4) Maximal simultaneous contraction of both transverse abdominal muscle and levator ani muscle, 5) Maximal simultaneous contraction of both transverse abdominal muscle and levator ani muscle with front side resistance added to both knee, 6) Maximal simultaneous contraction of both transverse abdominal muscle and levator ani muscle with diagonal resistance added to both knees, and 7) Maximal simultaneous contraction of both transverse abdominal muscle and levator ani muscle with lateral resistance added to both knees. [Results] The thicknesses of transverse abdominal muscle during maximal simultaneous contraction and maximal simultaneous contraction with resistance were greater than during the resting state. [Conclusion] The muscle output during simultaneous contraction and resistance movement were larger than that of each individual muscle.

Intrapartal pelvic floor protection: a pragmatic and interdisciplinary approach between obstetrics and urogynecology

Pelvic floor protection is an issue of increasing relevance. This article sought to summarize the session at last year's annual meeting of the German Society of Gynecology and Obstetrics (DGGG) in Stuttgart (10/2016) called "Urogynecology 2020-what is the optimal rate of cesarean section-does urogynecology have to deal with Obstetrics?". The main focus was set on the two important anatomical structures, the levator ani muscle and the anal sphincters. Operative vaginal delivery, epidural anesthesia, and episiotomy are subject to discussion.

Evaluation of isolated urinary stress incontinence according to the type of levator ani muscle lesion using 3/4D transperineal ultrasound 36 months post-partum

INTRODUCTION

Vaginal delivery can lead to pelvic floor disorders. Many authors have described pelvic floor injuries that can predict future defects such as urinary incontinence and pelvic organ prolapse. We propose the assessment of urinary stress incontinence and its association with levator ani muscle (LAM) microtrauma (>20% in the levator hiatus area during Valsalva) and macrotraumas (avulsion) identified by 3/4D transperineal ultrasound (3D-TpUS) 36 months post-partum.

MATERIALS AND METHODS

This was a prospective observational study including 168 nulliparous women. All patients included were nulliparous with singleton gestation in cephalic presentation, at ≥37 weeks and were recruited on the first day after delivery. Thirty-six months after delivery, 3D-TpUS was carried out to identify LAM lesions (macro or micro). Clinical assessment of urinary stress incontinence (USI) was based on the ICIQ-UI-SF test; a simple stress test and urodynamic test were carried out in the same visit.

RESULTS

A total of 105 nulliparous women were studied (51 spontaneous deliveries [SpD] and 54 vacuum-assisted deliveries [VD]). Microtraumas were identified in 35.3% of SpD and 20.4% of VD. Macrotraumas (avulsion) were identified in 9.8% of SpD and 35.2% of VD (p = 0.006). No differences were found in USI between study groups or in relation to the identification of LAM defects (19.2% in the no lesion group, 25% in the macrotrauma and 13.8% in the microtrauma groups; p = not significant). Nor were significant differences found in the results from the different study groups in the International Consultation on Incontinence Modular Questionnaire Urinary Incontinence Short Form (ICIQ-UI SF) test (12.7±2.2 in the no lesion group, 12.5±4.2 in the macrotrauma and 13.25±4.8 in the microtrauma groups; p = NS).

CONCLUSION

No difference was observed in USI between patients with and without LAM lesions (microtrauma or macrotrauma) 36 months post-delivery.

Finite element model focused on stress distribution in the levator ani muscle during vaginal delivery

Introduction and hypothesis

During vaginal delivery, the levator ani muscle (LAM) undergoes severe deformation. This stress can lead to stretch-related LAM injuries. The objective of this study was to develop a sophisticated MRI-based model to simulate changes in the LAM during vaginal delivery.

Methods

A 3D finite element model of the female pelvic floor and fetal head was developed. The model geometry was based on MRI data from a nulliparous woman and 1-day-old neonate. Material parameters were estimated using uniaxial test data from the literature and by least-square minimization method. The boundary conditions reflected all anatomical constraints and supports. A simulation of vaginal delivery with regard to the cardinal movements of labor was then performed.

Results

The mean stress values in the iliococcygeus portion of the LAM during fetal head extension were 4.91–7.93 MPa. The highest stress values were induced in the pubovisceral and puborectal LAM portions (mean 27.46 MPa) at the outset of fetal head extension. The last LAM subdivision engaged in the changes in stress was the posteromedial section of the puborectal muscle. The mean stress values were 16.89 MPa at the end of fetal head extension. The LAM was elongated by nearly 2.5 times from its initial resting position.

Conclusions

The cardinal movements of labor significantly affect the subsequent heterogeneous stress distribution in the LAM. The absolute stress values were highest in portions of the muscle that arise from the pubic bone. These areas are at the highest risk for muscle injuries with long-term complications.

Variability of the pubic arch architecture and its influence on the minimal levator hiatus area

OBJECTIVE

To investigate the association between the minimal levator hiatus (MLH) area at rest with its surrounding soft-tissue and bony structures in nulliparous asymptomatic women with a normal levator ani muscle.

METHODS

A subanalysis was undertaken of a prospective study of the appearance of the levator ani in asymptomatic nulliparous women conducted between September 2010 and September 2011. The subanalysis included women with a normal levator ani muscle. Three-dimensional ultrasonography volumes were used to obtain pelvic floor measurements.

RESULTS

The analysis included 56 women with mean age of 43.0±13.4years. The mean MLH area was 13.1±1.8cm(2) (range 9.0-17.3). The pubic arch angle had no influence on the MLH area (Pearson correlation coefficient r=0.13). Height and pubic arch length were positively correlated with the MLH area (r=0.26 [P=0.52] and r=0.50 [P<0.001], respectively).

CONCLUSION

The MLH size of nulliparous women varied widely and was positively correlated with the height and pubic arch length of the women. Therefore, caution is warranted when interpreting the MLH area as an indicator of a levator ani defect or a predictor of pelvic organ prolapse without taking a woman's pelvic bone characteristics into account.

[Anatomy of the levator ani muscle and implications for obstetrics and gynaecology]

Pelvic floor disorders include urogenital and anorectal prolapse, urinary and faecal incontinence. These diseases affect 25% of patients. Most of time, treatment is primarily surgical with a high post-operative risk of recurrence, especially for pelvic organ prolapse. Vaginal delivery is the major risk factor for pelvic floor disorders through levator ani muscle injury or nerve damage. After vaginal delivery, 20% of patients experiment elevator ani trauma. These injuries are more common in case of instrumental delivery by forceps, prolonged second phase labor, increased neonatal head circumference and associated anal sphincter injuries. Moreover, 25% of patients have temporary perineal neuropathy. Recently, pelvic three-dimensional reconstructions from RMI data allowed a better understanding of detailed levator ani muscle morphology and gave birth to a clear new nomenclature describing this muscle complex to be developed. Radiologic and anatomic studies have allowed exploring levator ani innervation leading to speculate on the muscle and nerve damage mechanisms during delivery. We then reviewed the levator ani muscle anatomy and innervation to better understand pelvic floor dysfunction observed after vaginal delivery.