Twisted orientation of the muscle bundles in the levator ani functional parts in women: Implications for pelvic floor support mechanism

This study presents a comprehensive investigation of the anatomical features of the levator ani muscle. The levator ani is a critical component of the pelvic floor; however, its intricate anatomy and functionality are poorly understood. Understanding the precise anatomy of the levator ani is crucial for the accurate diagnosis and effective treatment of pelvic floor disorders. Previous studies have been limited by the lack of comprehensive three-dimensional analyses; to overcome this limitation, we analysed the levator ani muscle using a novel 3D digitised muscle-mapping approach based on layer-by-layer dissection. From this examination, we determined that the levator ani consists of overlapping muscle bundles with varying orientations, particularly in the anteroinferior portion. Our findings revealed distinct muscle bundles directly attached to the rectum (LA-re) and twisted muscle slings surrounding the anterior (LA-a) and posterior (LA-p) aspects of the rectum, which are considered functional parts of the levator ani. These results suggest that these specific muscle bundles of the levator ani are primarily responsible for functional performance. The levator ani plays a crucial role in rectal elevation, lifting the centre of the perineum and narrowing the levator hiatus. The comprehensive anatomical information provided by our study will enhance diagnosis accuracy and facilitate the development of targeted treatment strategies for pelvic floor disorders in clinical practice.

Deep Diaphragmatic Breathing-Anatomical and Biomechanical Consideration

Background: Deep diaphragmatic breathing (DDB) involves slow and fully contraction of the diaphragm with expansion of the belly during inhalation, and slow and fully contraction of the abdominal muscles with reduction of the belly during exhalation. It is the key component of the holistic mind-body exercises commonly used for patients with multimorbidity. Purpose: The purpose of this study was to re-visit and address the fundamental anatomical and biomechanical consideration of the DDB with the relevant literature. Method: Peer-reviewed publications from last the 15 years were retrieved, reviewed, and analyzed. Findings: In this article, we described the updated morphological and anatomical characteristics of the diaphragm. Then, we elucidated in a biomechanical approach how and why the DDB can work on the gastrointestinal, cardiopulmonary, and nervous systems as well as on regulating the intra-abdominopelvic pressure and mind-body interaction to coordinate the diaphragm-pelvic floor-abdominal complex for a variety of physical and physiological activities. Conclusion: Understanding of this updated DDB knowledge may help holistic healthcare professionals including holistic nurses provide better patient education and care management during the DDB or DDB-based mind-body intervention time.

Comparative study of female pelvic floor among undeformed high-resolution thin-sectional anatomical (visible human) images and MRI and ultrasound images

PURPOSE

Using visible human, MRI and ultrasound images, we aim to provide an anatomical basis for the identification and diagnosis of pelvic floor structure and disease by ultrasound imaging.

METHODS

One Chinese visible human (CVH) image, one American visible human image, 9 MRI images of normal volunteers, and 40 ultrasound images of normal volunteers or pelvic organ prolapse patients were used. Pelvic organs, pelvic floor muscles, and the connective tissue in CVH, VHP, MRI, and ultrasound images were selected for comparative study.

RESULTS

We successfully identified the boundary of the anal sphincter complex, including the subcutaneous, superficial, and deep parts of the external anal sphincter, conjoined longitudinal muscles and internal anal sphincter; the levator ani muscle (LAM), including the internal and external parts of the pubovisceral muscle and the superficial and deep parts of the puborectal muscle; the urethral sphincter complex, including the urethral sphincter proper and the urethral compressor; and the perineal body, the rectoperineal muscle and superficial transverse perineal muscle.

CONCLUSIONS

We successfully recognized and studied the location, subdivisions, 2D morphology and spatial relationships of the LAM, anal sphincter complex, urethral sphincter complex and perineal body in ultrasound images, thereby helping sonologists or clinicians accurately identify pelvic floor muscles and supporting structures in ultrasound images.

[Dynamic magnetic resonance imaging of the pelvic floor: clinical application]

BACKGROUND

Dynamic magnetic resonance imaging (MRI) of the pelvic floor plays a key role in imaging complex pelvic floor dysfunction. The simultaneous detection of multiple findings in a complex anatomic setting renders correct analysis and clinical interpretation challenging.

OBJECTIVES

The most important aspects (anatomy of the pelvic floor, three compartment model, morphological and functional analysis, reporting) for a successful clinical use of dynamic MRI of the pelvic floor are summarized.

MATERIALS AND METHODS

Review of the scientific literature on dynamic pelvic MR imaging with special consideration of the joint recommendations provided by the expert panel of ESUR/ESGAR in 2016.

RESULTS

The pelvic floor is a complex anatomic structure, mainly formed by the levator ani muscle, the urethral support system and the endopelvic fascia. Firstly, morphological changes of these structures are analysed on the static sequences. Secondly, the functional analysis using the three compartment model is performed on the dynamic sequences during squeezing, straining and defecation. Pelvic organ mobility, pelvic organ prolapse, the anorectal angle and pelvic floor relaxation are measured and graded. The diagnosis of cystoceles, enteroceles, rectoceles, the uterovaginal as well as anorectal decent, intussusceptions and dyssynergic defecation should be reported using a structured report form.

CONCLUSIONS

A comprehensive analysis of all morphological and functional findings during dynamic MRI of the pelvic floor can provide information missed by other imaging modalities and hence alter therapeutic strategies.

Imaging the levator ani and the puborectalis muscle: implications in understanding regional anatomy, physiology and pathology

Purpose:To review the findings of recent dynamic imaging of the levator ani muscle in order to explain its function during defecation. Historical anatomical studies have suggested that the levator ani initiates defecation by lifting the anal canal, with conventional dissections and static radiologic imagery having been equated with manometry and electromyography.Materials and methods:An analysis of the literature was made concerning the chronological development of imaging modalities specifically designed to assess pelvic floor dynamics. Comparisons are made between imaging and electromyographic data at rest and during provocative manoeuvres including squeeze and strain.Results:The puborectalis muscle is shown distinctly separate from the levator ani and the deep external anal sphincter. In contrast to conventional teaching that the levator ani initiates defecation by lifting the anus, dynamic illustration defecography (DID) has confirmed that the abdominal musculature and the diaphragm instigate defecation with the transverse and vertical component portions of the levator ani resulting in descent of the anus. Current imaging has shown a tendinous peripheral structure to the termination of the conjoint longitudinal muscle, clarifying the anatomy of the perianal spaces. Planar oXy defecography has established patterns of movement of the anorectal junction that separate controls from those presenting with descending perineum syndrome or with anismus (paradoxical puborectalis spasm).Conclusions:Dynamic imaging of the pelvic floor (now mostly with MR proctography) has clarified the integral role of the levator ani during defecation. Rather than lifting the rectum, the muscle ensures descent of the anal canal.

Urogynecology in obstetrics: impact of pregnancy and delivery on pelvic floor disorders, a prospective longitudinal observational pilot study

Purpose

To assess changes in the pelvic floor anatomy that cause pelvic floor disorders (PFDs) in primigravidae during and after pregnancy and to evaluate their impact on women’s quality of life (QoL).

Methods

POP-Q and translabial ultrasound examination was performed in the third trimester and 3 months after delivery in a cohort of primigravidae with singleton pregnancy delivering in a tertiary center. Results were analyzed regarding mode of delivery and other pre- and peripartal factors. Two individualized detailed questionnaires were distributed at 3 months and at 12 months after childbirth to determinate QoL.

Results

We recruited 45 women, of whom 17 delivered vaginally (VD), 11 received a vacuum extraction delivery (VE) and 17 a Cesarean section in labor (CS). When comparing third-trimester sonography to 3 months after delivery, bladder neck mobility increased significantly in each delivery group and hiatal area increased significantly in the VD group. A LAM avulsion was found in two women after VE. Connective tissue weakness (p = 0.0483) and fetal weight at birth (p = 0.0384) were identified as significant risk factors for the occurrence of PFDs in a multivariant regression analysis. Urinary incontinence was most common with 15% and 11% of cases at 3, respectively, 12 months after delivery. 42% of women reported discomfort during sexual intercourse, 3 months after delivery and 24% 12 months postpartum. Although 93% of women engage a midwife after delivery, only 56% participated in pelvic floor muscle training.

Conclusion

Connective tissue weakness and high fetal weight at birth are important risk factors for the occurrence of PFDs. Nevertheless, more parturients should participate in postpartal care services to prevent future PFDs.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00404-021-06022-w.

Spatial distribution of smooth muscle tissue in the female pelvic floor and surrounding the urethra and vagina

Data regarding urethral supporting structures are insufficient for understanding the mechanism of stress urinary incontinence. Whether smooth muscle fibers contribute to urethral support and pelvic floor support structures is unclear. This study aimed to clarify the histological structures and spatial distributions of smooth muscle tissues surrounding the urethra and vagina. Using cadaveric specimens, macroscopic anatomical and histological evaluations were conducted. Six female cadavers were used for macroscopic observations. Ten female cadavers were used for histological observations. Three pelvises were cut in a plane vertical to the urethra, and the other pelvises were cut in a plane parallel to the urethra and vagina to observe tissues surrounding the urethra and vagina. The major tissue component around the proper muscle layer of the urethra was smooth muscle tissue, which mediated among the urethra, pubis, and levator ani. Smooth muscle tissues laterally extended the smooth muscle fibers, both superiorly and inferiorly toward the levator ani, with a few fibers inserted in the levator ani. Smooth muscle was found between the urethral walls and pubic bones. Smooth muscle may contribute to the mechanism of pelvic floor support.

Three muscle slings of the pelvic floor in women: an anatomic study

The region anterior to the anal canal in women is composed of intertwined smooth and skeletal muscles. The present study aimed to clarify skeletal muscle morphology in the anterior region of the anal canal. The pelvic floor muscles of 28 pelvic halves from 16 female cadavers (mean age 79.75 years) were dissected from the inferior aspect to examine the perineal muscles, followed by midline transection and dissection from the inner surface to examine the pelvic outlet muscles. The bulbospongiosus muscle was found to be attached to the lateral surface of the external anal sphincter. The superficial transverse perineal muscle crossed superiorly to the bulbospongiosus and coursed medially toward its contralateral muscle bundle deep to the anterior portion of the external anal sphincter. The superficial transverse perineal muscle formed the middle sling. From the medial aspect, the anterior part of the levator ani was divided into anterior and posterior bundles to form the anterior and posterior slings, respectively. This study proposes that three muscular slings could be important in supporting the pelvic floor in women. In addition, this study shows that the anterior skeletal muscular wall of the anal canal is composed of the anterior muscle bundle of the levator ani, superficial transverse perineal, and proper external anal sphincter muscles.

A novel measurement of pelvic floor cross-sectional area in older and younger women with and without prolapse

BACKGROUND

An increase in size of the aperture of the pelvis that must be spanned by pelvic floor support structures translates to an increase in the force on these structures. Prior studies have measured the bony dimensions of the pelvis, but the effect of changes in muscle bulk that may affect the size of this area are unknown.

OBJECTIVES

To develop a technique to evaluate the aperture size in the anterior pelvis at the level of the levator ani muscle attachments, and to identify age-related changes in women with and without prolapse.

MATERIALS AND METHODS

This was a technique development and pilot case-control study evaluating pelvic magnetic resonance imaging from 30 primiparous women from the Michigan Pelvic Floor Research Group MRI Data Base: 10 younger women with normal support, 10 older women with prolapse, and 10 older menopausal women without prolapse. Anterior pelvic area measurements were made in a plane that included the bilateral ischial spines and the inferior pubic point, approximating the level of the arcus tendineus fascia pelvis. Measurements of the anterior pelvic area, obturator internus muscles, and interspinous diameter were made by 5 independent raters from the Society of Gynecologic Surgeons Pelvic Anatomy Group who focused on developing pelvic imaging techniques, and evaluating interrater reliability. Demographic characteristics were compared across groups of interest using the Wilcoxon rank sum test, χ2, or Fisher exact test where appropriate. Multiple linear regression models were created to identify independent predictors of anterior pelvic area.

RESULTS

Per the study design, groups differed in age and prolapse stage. There were no differences in race, height, body mass index, gravidity, or parity. Patients with prolapse had a significantly longer interspinous diameter, and more major (>50% of the muscle) levator ani defects when compared to both older and younger women without prolapse. Interrater reliability was high for all measurements (intraclass correlation coefficient = 0.96). The anterior pelvic area (cm2) was significantly larger in older women with prolapse compared to older (60 ± 5.1 vs 53 ± 4.9, P = .004) and younger (60 ± 5.1 vs 52 ± 4.6, P = .001) women with normal support. The younger and older women with normal support did not differ in anterior pelvic area (52 ± 4.6 vs 53 ± 4.9, P = .99). After adjusting for race and body mass index, increased anterior pelvic area was significantly associated with the following: being an older woman with prolapse (β = 6.61 cm2, P = .004), and interspinous diameter (β = 4.52 cm2, P = .004).

CONCLUSION

Older women with prolapse had the largest anterior area, suggesting that the anterior pelvic area is a novel measure to consider when evaluating women with prolapse. Interspinous diameter, and being an older woman with prolapse, were associated with a larger anterior pelvic area. This suggests that reduced obturator internus muscle size with age may not be the primary factor in determining anterior pelvic area, but that pelvic dimensions such as interspinous diameter could play a role. The measurements were highly repeatable. The high intraclass correlation coefficient indicates that all raters were able to successfully learn the imaging software and to perform measurements with high reproducibility.

Echogenicity of puborectalis muscle, cervix and vastus lateralis muscle in pregnancy in relation to mode of delivery

OBJECTIVES

To confirm our previous observation that levator hiatal dimensions and mean echogenicity of the puborectalis muscle (MEP) are significantly different at 12 weeks' gestation in women who delivered by Cesarean section due to failure to progress compared with those who delivered vaginally. The secondary objective was to assess the association between the echogenicity of the cervix and vastus lateralis muscle and mode of delivery.

METHODS

In this prospective multicenter study, 306 nulliparous women with a singleton pregnancy underwent ultrasound assessments of the pelvic floor at rest, on maximum pelvic floor muscle contraction and on maximum Valsalva maneuver, of the cervix and of the vastus lateralis muscle at 12 weeks' gestation. Dimensions of the levator hiatus, MEP and mean echogenicity of the cervix and vastus lateralis muscle were measured and compared according to mode of delivery.

RESULTS

Two hundred and forty-nine women were included in the analyses. We were unable to confirm our previous finding that MEP and levator hiatal transverse diameter and area at 12 weeks' gestation are associated significantly with mode of delivery. In addition, we could not demonstrate a significant association between echogenicity of the cervix or vastus lateralis muscle and mode of delivery. Overall, MEP was a mean of 20 points lower in women in the new database as compared with the previous study, despite the use of the same ultrasound equipment.

CONCLUSION

In a second, independent multicenter dataset, we were unable to confirm our previous finding that levator hiatal dimensions and MEP on pelvic floor muscle contraction are associated significantly with mode of delivery. We also found no association between echogenicity of the cervix or vastus lateralis and mode of delivery. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Does levator ani hiatal area configuration affect pelvic organ prolapse?

OBJECTIVE

Levator ani trauma and hiatal overdistension have been shown to be associated with female pelvic organ prolapse (POP); however, the role of the shape of the levator hiatus in POP has not been examined to date. The aim of this study was to investigate the association between the configuration of the levator ani hiatus and POP.

METHODS

This was a retrospective study of 547 women who attended a tertiary urogynecological center for symptoms of pelvic floor and lower urinary tract dysfunction between October 2014 and August 2016. All women underwent a standardized interview and prolapse assessment using the International Continence Society (ICS) Pelvic Organ Prolapse Quantification (POP-Q) method and four-dimensional translabial ultrasound (TLUS). Measurements of the hiatal anteroposterior diameter (APD), coronal diameter (CD) and hiatal area (HA), at rest and on maximal Valsalva maneuver, and those of organ descent were performed offline at a later date by an investigator blinded to all other data. Hiatal configuration was defined as the ratio APD/CD. Associations between HA and HA adjusted by APD/CD at rest and on maximal Valsalva and symptoms and signs of prolapse were analyzed statistically using logistic regression modelling.

RESULTS

The mean age of the women was 54 ± 13.6 (range, 16-89) years. Of the 547 women included, 241 (44%) presented with prolapse symptoms. Clinically significant POP was detected in 406 (74%) patients and significant prolapse on TLUS was detected in 331 (61%). Hiatal ballooning was observed in 310 (57%) women and this was strongly associated with signs and symptoms of POP. HA at rest and on Valsalva was associated with significant POP both on clinical examination and on TLUS. Adjusted odds ratios for hiatal shape showed no effect of the hiatal configuration on the association between HA and POP.

CONCLUSION

Hiatal shape does not seem to influence the association between HA and symptoms and signs of prolapse. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Definition of apical descent in women with and without previous hysterectomy: A retrospective analysis

Background

While normal pelvic organ support has been defined for women with intact uterus, this is not the case for post- hysterectomy vault descent. A recent systematic review found that definitions of apical prolapse are highly variable.

Objectives

To investigate the relationship between prolapse symptoms and apical POP-Q measurements and establish cutoffs for ‘significant apical descent using receiver–operator characteristics (ROC) statistics.

Study design

Retrospective analysis of patients seen at a tertiary urogynecological unit. Evaluation included a standardized interview and clinical assessment using the Pelvic Organ Prolapse Quantification (POP-Q) system. ROC curves were prepared for the relationship between prolapse symptoms and POP-Q measure “C”.

Results

The records of 3010 women were available for analysis. Prolapse symptoms were reported by 52.3% (n = 1573), with a mean bother of 5.9 (SD 3.0, range 0–10). POP-Q point “C” was associated with symptoms of prolapse (p <0.0001) and prolapse bother (p <0.0001) on both univariate and multivariate analysis. ROC curves for women with and without uterus were similar, although the relationship between apical descent and symptoms of prolapse was stronger for women with uterus (AUC 0.728 versus 0.678). After controlling for multi-compartment prolapse, the models improved, resulting in AUCs of 0.782 and 0.720. For prediction of prolapse symptoms, cutoffs were set at C = -5 (sensitivity 0.73, specificity 0.67 with uterus in situ, sensitivity 0.59, specificity, 0.73 after hysterectomy).

Conclusion

A cut- off for ‘significant central compartment descent’ of 5 cm above the hymen on Valsalva seems valid regardless of previous hysterectomy.

A computer-based simulation of childbirth using the partial Dirichlet-Neumann contact method with total Lagrangian explicit dynamics on the GPU

During physiological or 'natural' childbirth, the fetal head follows a distinct motion pattern-often referred to as the cardinal movements or 'mechanisms' of childbirth-due to the biomechanical interaction between the fetus and maternal pelvic anatomy. The research presented in this paper introduces a virtual reality-based simulation of physiological childbirth. The underpinning science is based on two numerical algorithms including the total Lagrangian explicit dynamics method to calculate soft tissue deformation and the partial Dirichlet-Neumann contact method to calculate the mechanical contact interaction between the fetal head and maternal pelvic anatomy. The paper describes the underlying mathematics and algorithms of the solution and their combination into a computer-based implementation. The experimental section covers first a number of validation experiments on simple contact mechanical problems which is followed by the main experiment of running a virtual reality childbirth. Realistic mesh models of the fetus, bony pelvis and pelvic floor muscles were subjected to the intra-uterine expulsion forces which aim to propel the virtual fetus through the virtual birth canal. Following a series of simulations, taking variations in the shape and size of the geometric models into account, we consistently observed the cardinal movements in the simulator just as they happen in physiological childbirth. The results confirm the potential of the simulator as a predictive tool for problematic childbirths subject to patient-specific adaptations.

Anatomy and biomechanic of the musculus levator ani

OBJECTIVE

The aim of the rewiew is to provide complex new informations about anatomy and biomechanics features of the musculus levator ani. Described are risk factors leading to it´s injury and options of imaging the muscle complex (ultrasound, magnetic imaging resonance and 3D modeling).

DESIGN

Review.

SETTINGS

Departement of Obstetrics and Gynaecology, Hospital in Frýdek-Místek, GONA Co. Ltd , Institute for Mother and Child Prague.

RESULTS

Musculus levator ani (MLA) has a complex structure composed mainly of striated muscles. Minority of smooth muscle fibres are also found. Particular parts of the MLA hold together different angles. Inervation is provided through somatic and visceral nerve fibres. During delivery, more there three times stretching of the muscle was observed. Less strenght is needed do the same stretching of the muscle in repeating stress situations. In the MRI studies, two types of injury of the MLA, were found. Predisponed to the injury is medial part of the MLA known as pubovisceral muscle (PVM). PVM has three insertions. The most fragile is it´s medial insertion to the pubic bone described as enthesis. During experimental delivery studies was found, that the pressure in this part of the muscle reach almost 36MPa.

CONCLUSION

MLA is a difficult muscle. Because of the ethical reasons we don´t have, and probably never will have informations, how structuraly and elasticaly differs muscle, that was damaged during the delivery, compared to muscle without any damage. Promising are computer delivery simulations. In future, they would give us an answer, how risky is vaginal delivery in concrete expectant mother.

Automatic segmentation of puborectalis muscle on three-dimensional transperineal ultrasound

OBJECTIVES

The introduction of three-dimensional (3D) analysis of the puborectalis muscle (PRM) for diagnostic purposes into daily practice is hindered by the need for appropriate training of observers. Automatic segmentation of the PRM on 3D transperineal ultrasound may aid its integration into clinical practice. The aims of this study were to present and assess a protocol for manual 3D segmentation of the PRM on 3D transperineal ultrasound, and to use this for training of automatic 3D segmentation method of the PRM.

METHODS

The data used in this study were derived from 3D transperineal ultrasound sequences of the pelvic floor acquired at 12 weeks' gestation from nulliparous women with a singleton pregnancy. A manual 3D segmentation protocol was developed for the PRM based on a validated two-dimensional segmentation protocol. For automatic segmentation, active appearance models of the PRM were developed, trained using manual segmentation data from 50 women. The performances of both manual and automatic segmentation were analyzed by measuring the overlap and distance between the segmentations. Intraclass correlation coefficients (ICCs) and their 95% CIs were determined for mean echogenicity and volume of the puborectalis muscle, in order to assess inter- and intraobserver reliabilities of the manual method using data from 20 women, as well as to compare the manual and automatic methods.

RESULTS

Interobserver reliabilities for mean echogenicity and volume were very good for manual segmentation (ICCs 0.987 and 0.910, respectively), as were intraobserver reliabilities (ICCs 0.991 and 0.877, respectively). ICCs for mean echogenicity and volume were very good and good, respectively, for the comparison of manual vs automatic segmentation (0.968 and 0.626, respectively). The overlap and distance results for manual segmentation were as expected, showing an average mismatch of only 2-3 pixels and reasonable overlap. Based on overlap and distance, five mismatches were detected for automatic segmentation, resulting in an automatic segmentation success rate of 90%.

CONCLUSIONS

This study presents a reliable manual segmentation protocol and automatic 3D segmentation method for the PRM, which will facilitate future investigation of the PRM, allowing for the reliable measurement of potentially clinically valuable parameters such as mean echogenicity. © 2017 The Authors. Ultrasound in Obstetrics & Gynecology Published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Does vaginal delivery cause more damage to the pelvic floor than cesarean section as determined by 3D ultrasound evaluation? A systematic review

INTRODUCTION AND HYPOTHESIS

Pregnancy and delivery are well-established risk factors for pelvic floor dysfunction (PFD), but the physiopathology, such as the delivery route, is not well understood. This study evaluated the impact of delivery route on the pelvic floor muscles via 3D ultrasound.

METHODS

This review is registered in the PROSPERO database. The criteria for inclusion were prospective studies with 3D translabial ultrasound assessment in primigravida women during pregnancy and postpartum published in English, Spanish or Portuguese between 1980 and 2016. We excluded studies that did not include the topic of urogenital hiatus measurement and literature reviews. The MeSH terms were obstetric delivery, postpartum period, labor, parturition, three-dimensional images, ultrasonography, pelvic floor, and pelvic floor disorders.

RESULTS

The search retrieved 155 articles. After analysis, 6 articles were included. Four studies showed that vaginal delivery (VD) was associated with a larger hiatal area. One study associated the hiatal area with levator ani muscle (LAM) defects in VD. Four articles evaluated the bladder neck, 3 of which showed a significant increase in bladder neck mobility associated with VD and 1 showed decreased bladder neck elevation, not associated with the delivery mode; the first 3 articles all evaluated LAM injuries and showed an association between VD and LAM injury. Women who underwent VD presented defects of the puborectalis muscle.

CONCLUSIONS

Vaginal delivery was associated with a higher number of LAM injuries, puborectalis defects, increased bladder neck mobility, and enlargement of the hiatal area.

Detailed muscular structure and neural control anatomy of the levator ani muscle: a study based on female human fetuses

BACKGROUND

Injury to the levator ani muscle or pelvic nerves during pregnancy and vaginal delivery is responsible for pelvic floor dysfunction.

OBJECTIVE

We sought to demonstrate the presence of smooth muscular cell areas within the levator ani muscle and describe their localization and innervation.

STUDY DESIGN

Five female human fetuses were studied after approval from the French Biomedicine Agency. Specimens were serially sectioned and stained by Masson trichrome and immunostained for striated and smooth muscle, as well as for somatic, adrenergic, cholinergic, and nitriergic nerve fibers. Slides were digitized for 3-dimensional reconstruction. One fetus was reserved for electron microscopy. We explored the structure and innervation of the levator ani muscle.

RESULTS

Smooth muscular cell beams were connected externally to the anococcygeal raphe and the levator ani muscle and with the longitudinal anal muscle sphincter. The caudalmost part of the pubovaginal muscle was found to bulge between the rectum and the vagina. This bulging was a smooth muscular interface between the levator ani muscle and the longitudinal anal muscle sphincter. The medial (visceral) part of the levator ani muscle contained smooth muscle cells, in relation to the autonomic nerve fibers of the inferior hypogastric plexus. The lateral (parietal) part of the levator ani muscle contained striated muscle cells only and was innervated by the somatic nerve fibers of levator ani and pudendal nerves. The presence of smooth muscle cells within the medial part of the levator ani muscle was confirmed under electron microscopy in 1 fetus.

CONCLUSION

We characterized the muscular structure and neural control of the levator ani muscle. The muscle consists of a medial part containing smooth muscle cells under autonomic nerve influence and a lateral part containing striated muscle cells under somatic nerve control. These findings could result in new postpartum rehabilitation techniques.

Quality of reporting of diagnostic accuracy studies on pelvic floor three-dimensional transperineal ultrasound: a systematic review

OBJECTIVE

In recent years, a large number of studies have been published on the clinical relevance of pelvic floor three-dimensional (3D) transperineal ultrasound. Several studies compare sonography with other imaging modalities or clinical examination. The quality of reporting in these studies is not known. The objective of this systematic review was to determine the compliance of diagnostic accuracy studies investigating pelvic floor 3D ultrasound with the Standards for Reporting of Diagnostic Accuracy (STARD) guidelines.

METHODS

Published articles on pelvic floor 3D ultrasound were identified by a systematic literature search of MEDLINE, Web of Science and Scopus databases. Prospective and retrospective studies that compared pelvic floor 3D ultrasound with other clinical and imaging diagnostics were included in the analysis. STARD compliance was assessed and quantified by two independent investigators, using 22 of the original 25 STARD checklist items. Items with the qualifier 'if done' (Items 13, 23 and 24) were excluded because they were not applicable to all papers. Each item was scored as reported (score = 1) or not reported (score = 0). Observer variability, the total number of reported STARD items per article and summary scores for each item were calculated. The difference in total score between STARD-adopting and non-adopting journals was tested statistically, as was the effect of year of publication.

RESULTS

Forty studies published in 13 scientific journals were included in the analysis. Mean ± SD STARD checklist score of the included articles was 16.0 ± 2.5 out of a maximum of 22 points. The lowest scores (< 50%) were found for reporting of handling of indeterminate results or missing responses, adverse events and the time interval between tests. Interobserver agreement for rating the STARD items was excellent (intraclass correlation coefficient, 0.77). An independent t-test showed no significant mean difference ± SD in total STARD checklist score between STARD-adopting and non-adopting journals (16.4 ± 2.2 vs 15.9 ± 2.6, respectively). Mean ± SD STARD checklist score for articles published in 2003-2009 was lower, but not statistically different, compared with those published in 2010-2015 (15.2 ± 2.5 vs 16.6 ± 2.4, respectively).

CONCLUSION

The overall compliance with reporting guidelines of diagnostic accuracy studies on pelvic floor 3D transperineal ultrasound is relatively good compared with other fields of medicine. However, specific checklist items require more attention when reported. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Apical Vaginal Support: The Often Forgotten Piece of the Puzzle

Pelvic organ prolapse is common among women who have delivered vaginally or had a hysterectomy. In a total hysterectomy, the apical vaginal support is transected. Although evidence supports re-establishment of apical support, our research showed that this rarely occurs in hysterectomies. To address our lack of definitions of "significant" apical support loss and recommendations to guide surgeons as to when they should perform an apical support procedure, we analyzed patient data and found that a simple assessment of the genital hiatus can effectively screen for significant apical support loss. Our work will hopefully highlight the importance of apical support loss and current deficits in research and clinical guidelines.

Recent Advances in Understanding Pelvic-Floor Tissue of Women With and Without Pelvic Organ Prolapse: Considerations for Physical Therapists

Pelvic organ prolapse is a fairly common condition that imposes significant symptoms, diminished quality of life, social burden, financial expense, and surgical risk on women. As evidence supporting the benefit of pelvic-floor muscle training in nonsurgical management of pelvic organ prolapse grows, physical therapists are becoming a provider of choice interacting with women affected by pelvic organ prolapse. This perspective article will review recent research on tissue characteristics of 3 key components of pelvic organ support: skeletal muscle, ligament, and vaginal wall. This information will be summarized as implications for physical therapists. An improved understanding of pelvic-floor tissue in women with and without pelvic organ prolapse will provide a more comprehensive appreciation of the interaction of multiple systems in the disorder.

A Geometric Capacity-Demand Analysis of Maternal Levator Muscle Stretch Required for Vaginal Delivery

Because levator ani (LA) muscle injuries occur in approximately 13% of all vaginal births, insights are needed to better prevent them. In Part I of this paper, we conducted an analysis of the bony and soft tissue factors contributing to the geometric "capacity" of the maternal pelvis and pelvic floor to deliver a fetal head without incurring stretch injury of the maternal soft tissue. In Part II, we quantified the range in demand, represented by the variation in fetal head size and shape, placed on the maternal pelvic floor. In Part III, we analyzed the capacity-to-demand geometric ratio, g, in order to determine whether a mother can deliver a head of given size without stretch injury. The results of a Part I sensitivity analysis showed that initial soft tissue loop length (SL) had the greatest effect on maternal capacity, followed by the length of the soft tissue loop above the inferior pubic rami at ultimate crowning, then subpubic arch angle (SPAA) and head size, and finally the levator origin separation distance. We found the more caudal origin of the puborectal portion of the levator muscle helps to protect it from the stretch injuries commonly observed in the pubovisceral portion. Part II fetal head molding index (MI) and fetal head size revealed fetal head circumference values ranging from 253 to 351 mm, which would increase up to 11 mm upon face presentation. The Part III capacity-demand analysis of g revealed that, based on geometry alone, the 10th percentile maternal capacity predicted injury for all head sizes, the 25th percentile maternal capacity could deliver half of all head sizes, while the 50th percentile maternal capacity could deliver a head of any size without injury. If ultrasound imaging could be operationalized to make measurements of ratio g, it might be used to usefully inform women on their level of risk for levator injury during vaginal birth.

Antenatal pelvic floor biometry is related to levator ani muscle injury

OBJECTIVE

To evaluate the relationship between antenatal pelvic floor biometry and levator ani muscle (LAM) injury in Chinese women.

METHODS

Three-dimensional transperineal ultrasound was performed in nulliparous Chinese women with a singleton pregnancy at 9-12 weeks, 26-28 weeks and 36-38 weeks of gestation and again at 12 months after delivery. Hiatal anteroposterior (AP) diameter, transverse diameter and area were measured on the antenatal ultrasound volumes obtained at rest, on Valsalva maneuver and during pelvic floor muscle contraction (PFMC). LAM injury was evaluated using ultrasound volumes obtained during PFMC at 12 months after delivery.

RESULTS

In total, 328 women completed the study. At 12 months after delivery, 38 (14.8% of those who delivered vaginally) women had LAM injury; 28 were unilateral (14 right- and 14 left-sided) and 10 were bilateral. In all three trimesters there was smaller hiatal AP diameter and hiatal area in women with LAM injury when compared with women without injury. On multivariable analysis of the three factors, hiatal AP diameter at rest, hiatal area at rest and operative vaginal delivery, only hiatal AP diameter at rest in all three trimesters was an independent factor of LAM injury. A larger hiatal AP diameter at rest in the first, second and third trimesters reduced the likelihood of LAM injury with odds ratios of 0.21, 0.15 and 0.21, respectively.

CONCLUSIONS

A smaller antenatal hiatal AP diameter at rest is a risk factor for LAM injury. The hiatal AP diameter is relatively simple to measure and the error in measurement is relatively small. A prospective study to confirm this relationship and to explore whether this measurement, performed in the midsagittal plane, is repeatable should be performed. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Impact of vaginal parity and aging on the architectural design of pelvic floor muscles

BACKGROUND

Vaginal delivery and aging are key risk factors for pelvic floor muscle dysfunction, which is a critical component of pelvic floor disorders. However, alterations in the pelvic floor muscle intrinsic structure that lead to muscle dysfunction because of childbirth and aging remain elusive.

OBJECTIVES

The purpose of this study was to determine the impact of vaginal deliveries and aging on human cadaveric pelvic floor muscle architecture, which is the strongest predictor of active muscle function.

STUDY DESIGN

Coccygeus, iliococcygeus, and pubovisceralis were obtained from younger donors who were ≤51 years old, vaginally nulliparous (n = 5) and vaginally parous (n = 6) and older donors who were >51 years old, vaginally nulliparous (n = 6) and vaginally parous (n = 6), all of whom had no history of pelvic floor disorders. Architectural parameters, which are predictive of muscle's excursion and force-generating capacity, were determined with the use of validated methods. Intramuscular collagen content was quantified by hydroxyproline assay. Main effects of parity and aging and the interactions were determined with the use of 2-way analysis of variance, with Tukey's post-hoc testing and a significance level of .05.

RESULTS

The mean age of younger and older donors differed by approximately 40 years (P = .001) but was similar between nulliparous and parous donors within each age group (P > .9). The median parity was 2 (range, 1-3) in younger and older vaginally parous groups (P = .7). The main impact of parity was increased fiber length in the more proximal coccygeus (P = .03) and iliococcygeus (P = .04). Aging changes manifested as decreased physiologic cross-sectional area across all pelvic floor muscles (P < .05), which substantially exceeded the age-related decline in muscle mass. The physiologic cross-sectional area was lower in younger vaginally parous, compared with younger vaginally nulliparous, pelvic floor muscles; however, the differences did not reach statistical significance. Pelvic floor muscle collagen content was not altered by parity but increased dramatically with aging (P < .05).

CONCLUSIONS

Increased fiber length in more proximal pelvic floor muscles likely represents an adaptive response to the chronically increased load placed on these muscles by the displaced apical structures, presumably as a consequence of vaginal delivery. In younger specimens, a consistent trend towards decrease in force-generating capacity of all pelvic floor muscles in the parous group suggests a potential mechanism for clinically identified pelvic floor muscle weakness in vaginally parous women. The substantial decrease in predicted muscle force production and fibrosis with aging represent likely mechanisms for the pelvic floor muscle dysfunction in older women.

Reproducibility in pelvic floor biometric parameters of nulliparous women assessed by translabial three-dimensional ultrasound using Omniview reformatting technique

AIM

To assess the reproducibility of pelvic floor biometric parameters by translabial three-dimensional ultrasound compared with the OmniView® reformatting technique.

MATERIAL AND METHODS

We performed a cross-sectional study involving 47 nulliparous women without symptoms of pelvic floor dysfunction. The hiatal area and right pubovisceral muscle width measurements were performed in the axial plane using both 3D ultrasound in the rendering mode and OmniView® techniques. To determine the occurrence of standardized error between examiners and the two sonographic methods, the paired t-test was used. The intra- and inter-observer reliability and agreement were estimated by concordance correlation coefficient (CCC) and limits of agreement, respectively.

RESULTS

We did not observe significant statistical differences among both measurements performed by the first examiner, both examiners and both methods in the assessment of the hiatal area; however, the measurements of the right pubovisceral muscle were significantly lower using OmniView®. The intra-observer reliability was good in the evaluation of all pelvic floor parameters; however, the inter-observer reliability was good only to the 3D rendering mode (CCC=0.87). The intra-observer agreement was good in the assessment of all pelvic floor parameters; however, the inter-observer agreement was found to be good only when 3DUS in the rendering mode was used (<+/-15%).

CONCLUSION

Both 3D ultrasound in the rendering mode and OmniView® reformatting techniques were concordant in the assessment of pelvic floor parameters; however, the 3D ultrasound rendering in the mode demonstrated better inter-observer reliability and agreement.

Defecography: a still needful exam for evaluation of pelvic floor diseases

The aim of this discussion is to describe what is a defecography, how we have to perform it, what can we see and to present the main physio-pathological illnesses of pelvic floor and anorectal region that can be studied with this method and its advantages over other screening techniques. Defecography is a contrastographic radiological examination that highlights structural and functional pelvic floor diseases. Upon preliminary ileum-colic opacification giving to patient radiopaque contrast, are first acquired static images (at rest, in maximum voluntary contraction of the pelvic muscles, while straining) and secondarily dynamic sequences (during evacuation), allowing a complete evaluation of the functionality of the anorectal region and the pelvic floor. Defecography is an easy procedure to perform widely available, and economic, carried out in conditions where the patient experiences symptoms, the most realistic possible. It can be still considered reliable technology and first choice in many patients in whom the clinic alone is not sufficient and it is not possible or necessary to perform a study with MRI.

Is pelvic organ support different between young nulliparous African and Caucasian women?

OBJECTIVE

There seems to be substantial variation in the prevalence of pelvic floor disorders between different ethnic groups. This may be due partially to differences in pelvic floor structure and functional anatomy. To date, data on this issue are sparse. The aim of this study was to compare hiatal dimensions, pelvic organ descent and levator biometry in young, healthy nulliparous Caucasian and African women.

METHODS

Healthy nulliparous non-pregnant volunteers attending a local nursing school in Uganda were invited to participate in this study during two fistula camps. All volunteers underwent a simple physician-administered questionnaire and a four-dimensional translabial ultrasound examination. Offline analysis was performed to assess hiatal dimensions, pelvic organ descent, levator muscle thickness and area. To compare findings with those obtained in nulliparous non-pregnant Caucasians, we retrieved the three-dimensional/four-dimensional ultrasound volume datasets of a previously published study.

RESULTS

The dataset of 76 Ugandan and 49 Caucasian women was analyzed. The two groups were not matched but they were comparable in age and body mass index. All measurements of hiatal dimensions and pelvic organ descent were significantly higher among the Ugandans (all P ≤ 0.01); however, muscle thickness and area were not significantly different between the two groups.

CONCLUSIONS

Substantial differences between Caucasian and Ugandan non-pregnant nulliparae were identified in this study comparing functional pelvic floor anatomy. It appears likely that these differences in functional anatomy are at least partly genetic in nature. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Estimated levator ani subtended volume: a novel assay for predicting surgical failure after uterosacral ligament suspension

BACKGROUND

Levator ani muscle complex plays an important role in pelvic support and defects or laxity in this muscle complex contributes to pelvic organ prolapse and recurrence after surgical repair.

OBJECTIVE

The purpose of this study was to determine whether estimated levator ani subtended volume can predict surgical outcomes for laparoscopic bilateral uterosacral ligament suspension.

STUDY DESIGN

A retrospective cohort study was performed in patients who underwent laparoscopic uterosacral ligament suspension from 2010-2012. Only patients with a preoperative pelvic magnetic resonance image were included. Surgical failure was defined as a composite score that included the presence of anatomic bulge beyond the hymen with sensation of vaginal bulge or repeat treatment for prolapse via pessary or surgery by 1-year follow-up evaluation. Standard protocol pelvic magnetic resonance imaging measurements pubococcygeal line, H-line, and M-line were collected along with the calculation of the width of the levator ani hiatus. Estimated levator ani subtended volume was calculated for each subject. An optimal cutoff point was calculated and compared against categoric values of surgical success/failure. A Fisher exact test, an area under receiver operating characteristics curve, and logistic regression analysis were performed. A probability value of <.05 was considered statistically significant.

RESULTS

Ninety-three women underwent laparoscopic bilateral uterosacral ligament suspension during study period. Of these, 66 women had a standardized preoperative pelvic magnetic resonance image per institutional protocol. Thirteen patients (19.6%) met the criteria for surgical failure by 1 year. An optimal cutoff point of 38.5 was calculated by Liu's method for optimization. Among the patients with defined surgical failures, 84.6% (11/13) had an estimated levator ani subtended volume above cutoff point of 38.5. Among the patients with defined surgical success, 39.6% (21/53) had an estimated levator ani subtended volume above the cutoff point (84.6% vs 39.6%; P = .0048) with a significant odds ratio of 8.38 (95% confidence interval, 1.69-41.68; P = .009). An area under receiver operating characteristics curve of 0.725 (95% confidence interval, 0.603-0.847), sensitivity of 84.6% (95% confidence interval, 54.6%-98.1%), and specificity of 60.4% (95% confidence interval, 46%-73.5%) at 38.5 were predictors of surgical success/failure by 1 year. Logistic regression analysis demonstrated no significant confounders among age, body mass index, stage, or parity.

CONCLUSIONS

Estimated levator ani subtended volume may predict surgical failure for laparoscopic bilateral uterosacral ligament suspension. Patients with a calculated estimated levator ani subtended volume above 38.5 on a preoperative pelvic magnetic resonance imaging were associated with an increased risk for surgical failure by 1 year, regardless of age, body mass index, stage, or parity. Future investigation that will include repeatability, reliability analysis, and a prospective study is warranted.

Cystocele and functional anatomy of the pelvic floor: review and update of the various theories

INTRODUCTION AND HYPOTHESIS

We updated anatomic theories of pelvic organ support to determine pathophysiology in various forms of cystocele.

METHODS

PubMed/MEDLINE, ScienceDirect, Cochrane Library, and Web of Science databases were searched using the terms pelvic floor, cystocele, anatomy, connective tissue, endopelvic fascia, and pelvic mobility. We retrieved 612 articles, of which 61 matched our topic and thus were selected. Anatomic structures of bladder support and their roles in cystocele onset were determined on the international anatomic classification; the various anatomic theories of pelvic organ support were reviewed and a synthesis was made of theories of cystocele pathophysiology.

RESULTS

Anterior vaginal support structures comprise pubocervical fascia, tendinous arcs, endopelvic fascia, and levator ani muscle. DeLancey's theory was based on anatomic models and, later, magnetic resonance imaging (MRI), establishing a three-level anatomopathologic definition of prolapse. Petros's integral theory demonstrated interdependence between pelvic organ support systems, linking ligament-fascia lesions, and clinical expression. Apical cystocele is induced by failure of the pubocervical fascia and insertion of its cervical ring; lower cystocele is induced by pubocervical fascia (medial cystocele) or endopelvic fascia failure at its arcus tendineus fasciae pelvis attachment (lateral cystocele).

CONCLUSIONS

Improved anatomic knowledge of vaginal wall support mechanisms will improve understanding of cystocele pathophysiology, diagnosis of the various types, and surgical techniques. The two most relevant theories, DeLancey's and Petros's, are complementary, enriching knowledge of pelvic functional anatomy, but differ in mechanism. Three-dimensional digital models could integrate and assess the mechanical properties of each anatomic structure.

Anatomy and physiology of the lower urinary tract

Functions of the lower urinary tract to store and periodically eliminate urine are regulated by a complex neural control system in the brain, spinal cord, and peripheral autonomic ganglia that coordinates the activity of smooth and striated muscles of the bladder and urethral outlet. Neural control of micturition is organized as a hierarchic system in which spinal storage mechanisms are in turn regulated by circuitry in the rostral brainstem that initiates reflex voiding. Input from the forebrain triggers voluntary voiding by modulating the brainstem circuitry. Many neural circuits controlling the lower urinary tract exhibit switch-like patterns of activity that turn on and off in an all-or-none manner. The major component of the micturition switching circuit is a spinobulbospinal parasympathetic reflex pathway that has essential connections in the periaqueductal gray and pontine micturition center. A computer model of this circuit that mimics the switching functions of the bladder and urethra at the onset of micturition is described. Micturition occurs involuntarily during the early postnatal period, after which it is regulated voluntarily. Diseases or injuries of the nervous system in adults cause re-emergence of involuntary micturition, leading to urinary incontinence. The mechanisms underlying these pathologic changes are discussed.

Lack of striated muscle fibers in the longitudinal anal muscle of elderly Japanese: a histological study using cadaveric specimens

PURPOSE AND METHODS

The aim of this study is to investigate variations in the longitudinal anal muscle (LAM), especially in the meeting pattern between the levator ani and rectum at the origin of the LAM. We examined the histology of the anal canal and the lower rectum of 50 cadavers (25 males, 25 females) of elderly Japanese individuals with the aid of immunohistochemistry.

RESULTS

We observed two patterns in the meeting site between the levator ani and the rectum. In type 1, observed in 26 specimens, the smooth muscle-rich fascia lining the internal or medial aspect of the levator ani (i.e., the fascia pelvis parietalis or endopelvic fascia) was connected to the external muscle layer. In type 2, observed in 24 specimens, multiple intramuscular septa of the levator ani were attached to a smooth muscle mass, with the latter joining the external smooth muscle layer of the rectum. However, 21 specimens (6 type 1 and 15 type 2) carried few smooth muscles at the meeting site. We did not find any striated muscle in the LAM, although this might have been the result of age-associated degeneration. Thus, active traction of the pelvic viscera by the LAM seemed unlikely in elderly Japanese.

CONCLUSIONS

Rather than playing an active role, as suggested by the integral pelvic floor theory, the LAM seemed to be an elastic skeleton that maintains the shape of the anal canal.

Comparison of pelvic muscle architecture between humans and commonly used laboratory species

INTRODUCTION AND HYPOTHESIS

Pelvic floor muscles (PFM) are deleteriously affected by vaginal birth, which contributes to the development of pelvic floor disorders. To mechanistically link these events, experiments using animal models are required, as access to human PFM tissue is challenging. In choosing an animal model, a comparative study of PFM design is necessary, since gross anatomy alone is insufficient to guide the selection.

METHODS

Human PFM architecture was measured using micromechanical dissection and then compared with mouse (n = 10), rat (n = 10), and rabbit (n = 10) using the Architectural Difference Index (ADI) (parameterizing a combined measure of sarcomere length-to-optimal-sarcomere ratio, fiber-to-muscle-length ratio, and fraction of total PFM mass and physiological cross-sectional area (PCSA) contributed by each muscle). Coccygeus (C), iliocaudalis (IC), and pubocaudalis (PC) were harvested and subjected to architectural measurements. Parameters within species were compared using repeated measures analysis of variance (ANOVA) with post hoc Tukey's tests. The scaling relationships of PFM across species were quantified using least-squares regression of log-10-transformed variables.

RESULTS

Based on the ADI, rat was found to be the most similar to humans (ADI = 2.5), followed by mouse (ADI = 3.3). When animals' body mass was regressed against muscle mass, muscle length, fiber length, and PCSA scaling coefficients showed a negative allometric relationship or smaller increase than predicted by geometric scaling.

CONCLUSION

In terms of muscle design among commonly used laboratory animals, rat best approximates the human PFM, followed by mouse. Negative allometric scaling of PFM architectural parameters is likely due to the multifaceted function of these muscles.

A logarithmic opinion pool based STAPLE algorithm for the fusion of segmentations with associated reliability weights

Pelvic floor dysfunction is common in women after childbirth and precise segmentation of magnetic resonance images (MRI) of the pelvic floor may facilitate diagnosis and treatment of patients. However, because of the complexity of its structures, manual segmentation of the pelvic floor is challenging and suffers from high inter and intra-rater variability of expert raters. Multiple template fusion algorithms are promising segmentation techniques for these types of applications, but they have been limited by imperfections in the alignment of templates to the target, and by template segmentation errors. A number of algorithms sought to improve segmentation performance by combining image intensities and template labels as two independent sources of information, carrying out fusion through local intensity weighted voting schemes. This class of approach is a form of linear opinion pooling, and achieves unsatisfactory performance for this application. We hypothesized that better decision fusion could be achieved by assessing the contribution of each template in comparison to a reference standard segmentation of the target image and developed a novel segmentation algorithm to enable automatic segmentation of MRI of the female pelvic floor. The algorithm achieves high performance by estimating and compensating for both imperfect registration of the templates to the target image and template segmentation inaccuracies. A local image similarity measure is used to infer a local reliability weight, which contributes to the fusion through a novel logarithmic opinion pooling. We evaluated our new algorithm in comparison to nine state-of-the-art segmentation methods and demonstrated our algorithm achieves the highest performance.

Ultrasound imaging of the pelvic floor: changes in anatomy during and after first pregnancy

OBJECTIVES

To describe changes in the absolute values of levator hiatal dimensions and in the contractility and distensibility of the levator hiatus during pelvic floor contraction and Valsalva maneuver, using three/four-dimensional (3D/4D) transperineal ultrasound in women during and after their first pregnancy.

METHODS

Two-hundred and eighty nulliparous pregnant women underwent ultrasound examination at 12 and 36 weeks' gestation and 6 months postpartum. Hiatal dimensions were measured at rest, on pelvic floor contraction and on Valsalva maneuver. The contractility and distensibility were determined by the difference between hiatal dimensions at rest and those on contraction or Valsalva, respectively. After exclusions, there were 231 datasets from women at rest, 199 for pelvic floor contraction and 230 for Valsalva maneuver. Data at 36 weeks' gestation and 6 months postpartum were compared with data at 12 weeks' gestation.

RESULTS

At 36 weeks' gestation, the absolute values of hiatal dimensions and the contractility and distensibility of the levator hiatus were significantly increased compared with those at 12 weeks' gestation. Women who delivered vaginally showed a persistent significant increase in hiatal dimensions on Valsalva, whereas women who delivered by prelabor or first-stage Cesarean section showed no significant changes in hiatal dimensions on Valsalva. After both vaginal and Cesarean section delivery, there was a persistent increase in the distensibility of the hiatus during Valsalva compared with in early pregnancy.

CONCLUSION

During first pregnancy, the absolute values of levator hiatal dimensions and the contractility and distensibility of the levator hiatus increase. Regardless of delivery mode, increased distensibility of the levator hiatus during Valsalva persists after childbirth. This increased pelvic floor distensibility may play a role in the development of pelvic floor dysfunction in later life.

Measuring echogenicity and area of the puborectalis muscle: method and reliability

OBJECTIVES

To develop a semi-automated method to assess puborectalis muscle echogenicity on three-dimensional/four-dimensional (3D/4D) volume transperineal ultrasound images using 4D View and Matlab® software and evaluate its intra- and interobserver reliability.

METHOD

The data of 23 women in their first trimester were included. 3D/4D volume datasets were obtained at rest. Two inexperienced observers were trained by an experienced observer to construct tomographic ultrasound images (TUI) from the original data and to delineate all structures. Puborectalis muscle area (PMA) and the mean echogenicity of the puborectalis muscle (MEP) were calculated offline. Intra- and interobserver reliability were determined by intraclass correlation coefficients (ICC) and their 95% CIs.

RESULTS

The development of a semi-automated method to calculate puborectalis area and echogenicity is described in detail. PMA and MEP measurements in pregnant women demonstrated almost perfect intraobserver reliability for both inexperienced observers, with ICC values ranging from 0.88 to 0.99. The interobserver reliability showed ICCs of 0.63 for PMA and almost perfect ICC values, of 0.96-0.98, for echogenicity. The majority of intraobserver mismatch between two delineations of PMA occurred near the borders.

CONCLUSIONS

Matlab software can be used to provide reliable measurements of the area and echogenicity of the puborectalis muscle. As the latter can be used to assess structural changes in the puborectalis muscle, it appears a promising new tool for studying pelvic floor structural anatomy.

Comparison of muscle fiber directions between different levator ani muscle subdivisions: in vivo MRI measurements in women

INTRODUCTION AND HYPOTHESIS

This study describes a technique to quantify muscle fascicle directions in the levator ani (LA) and tests the null hypothesis that the in vivo fascicle directions for each LA subdivision subtend the same parasagittal angle relative to a horizontal reference axis.

METHODS

Visible muscle fascicle direction in the each of the three LA muscle subdivisions, the pubovisceral (PVM; synonymous with pubococcygeal), puborectal (PRM), and iliococcygeal (ICM) muscles, as well as the external anal sphincter (EAS), were measured on 3-T sagittal MRI images in a convenience sample of 14 healthy women in whom muscle fascicles were visible. Mean ± standard deviation (SD) angle values relative to the horizontal were calculated for each muscle subdivision. Repeated measures ANOVA and post-hoc paired t tests were used to compare muscle groups.

RESULTS

Pubovisceral muscle fiber inclination was 41 ± 8.0°, PRM was -19 ± 10.1°, ICM was 33 ± 8.8°, and EAS was -43 ± 6.4°. These fascicle directions were statistically different (p < 0.001). Pairwise comparisons among levator subdivisions showed angle differences of 60° between PVM and PRM, and 52° between ICM and PRM. An 84° difference existed between PVM and EAS. The smallest angle difference between levator divisions was between PVM and ICM 8°. The difference between PRM and EAS was 24°. All pairwise comparisons were significant (p < 0.001).

CONCLUSIONS

The null hypothesis that muscle fascicle inclinations are similar in the three subdivisions of the levator ani and the external anal sphincter was rejected. The largest difference in levator subdivision inclination, 60°, was found between the PVM and PRM.

[Anatomical characteristics of the pelvic floor muscles in young nulliparous women based on three-dimensional MRI]

OBJECTIVE

To analyse anatomical characteristics of the pelvic floor in young nulliparous volunteers based on three-dimensional MRI.

METHODS

Thin-slice MRI was performed in 25 young nulliparous volunteers in Southern Medical University, MRI were imported into Mimics 10.01 for 3D reconstruction.Using 3D models we measured follow indicators: the levator ani muscle volume (LVOL) , levator plate angle (LPA), levator hiatus width (LH-W)and length (LH-L), distance between symphysis and levator sling muscle (LSG).

RESULTS

(1) 25 cases of pelvic three-dimensional models was successfully constructed, including the pelvis, pelvic organs and the pelvic floor muscles (including the ischial coccyx muscle, levator ani muscle and its various components, perineal muscles), the models could be able to clearly reflect the level of the pelvic floor muscles; (2) 25 cases of levator ani muscle measurement results:LVOL: (34 ± 6) cm(3), LPA: (43 ± 4) °, LH-W: (33 ± 4) mm, LH-L: (54 ± 5) mm, left LSG: (18.8 ± 2.5) mm, right LSG: (18.3 ± 2.5) mm.

CONCLUSIONS

It is an effective way to use the computer to reconstruct the 3D model of female pelvic floor muscles using MRI data set. The quantitative analysis of levator ani muscle three-dimensional model can be assessed pelvic floor function, which is of great value in clinical practice.It is helpful to understand the pelvic floor disorders pathogenesis, clinical diagnosis, treatment options and treatment evaluation to provide reference standards.

Pelvic floor biometry in Chinese primiparous women 1 year after delivery: a prospective observational study

OBJECTIVES

To evaluate pelvic floor biometry in Chinese women 1 year following childbirth and to explore factors that affect it.

METHODS

Translabial ultrasound examination was performed at rest, on Valsalva maneuver (VM) and on pelvic floor muscle contraction (PFMC) in the first, second and third trimesters of pregnancy and at 8 weeks, 6 months and 12 months after delivery in a cohort of women delivering at term their first child. Offline analysis was undertaken to measure the position of the bladder neck, cervix, anorectal junction and hiatal dimensions at each posture and at each visit, and to detect levator ani muscle (LAM) injury on PFMC 8 weeks and 12 months after delivery. Results were analyzed according to mode of delivery.

RESULTS

We recruited 442 women, of whom 328 (74.2%) completed the study; there was LAM injury in 48 women at 8 weeks and in only 38 women at 12 months. When comparing first-trimester biometry to that at 12 months after delivery, the bladder neck was more distal on VM and bladder neck displacement was increased, and the cervix was lower at rest and on VM in the vaginal delivery group. In the Cesarean section group, bladder neck and anorectal junction were more distal on VM, the cervix was lower at rest, on VM and on PFMC, and the hiatal area was increased on VM. There was a greater increase in hiatal area after vaginal delivery. Overall, 34.8% had irreversible hiatal distension (> 20% increase in hiatal area after delivery as compared to first trimester). LAM injury was significantly associated with irreversible hiatal distension (odds ratios, 5.2-9.5 at different postures).

CONCLUSIONS

Pregnancy beyond 35 weeks of gestation has an effect on the pelvic floor of Chinese women, irrespective of mode of delivery. The pelvic organs remain more mobile after delivery when compared to in the first trimester, and there is no clear difference between the findings observed following vaginal delivery or Cesarean section, except in hiatal distension, which is greater after vaginal delivery. LAM injury is the factor most strongly associated with irreversible hiatal distension.

Intra- and interobserver reliability of levator ani muscle biometry and avulsion using three-dimensional endovaginal ultrasonography

OBJECTIVES

To test intra- and interobserver reliability of assessment of levator ani muscle (LAM) biometry and avulsion using antenatal and postnatal three-dimensional (3D) endovaginal ultrasonography (EVUS), and to determine levator-urethra gap (LUG) values on EVUS.

METHODS

Primigravid women were scanned prior to delivery, early postpartum and 3 months postpartum, with EVUS performed at rest using a standardized protocol. During post-processing, measurements were taken in the plane of minimal hiatal dimensions by two independent investigators blinded to the clinical information and each other's results. LAM attachment to the pubic bone was assessed at the pubococcygeus and puborectalis levels using a score system: (1) intact; (2) partial avulsion (< 50%); (3) partial avulsion (≥ 50%); and (4) complete avulsion. Intraclass correlation coefficients (ICCs) and limits of agreement (LOAs) were calculated for each time point, with intraobserver analysis conducted in a random sample of 20 women scanned 3 months following delivery.

RESULTS

One hundred and sixty-nine antenatal scans, 83 early postpartum scans and 75 scans at 3 months postpartum were performed. The intra- and interobserver ICCs, respectively, were 0.95 and 0.86-0.88 for hiatal area, 0.90 and 0.16-0.74 for hiatal transverse diameter, 0.91 and 0.73-0.80 for hiatal anteroposterior diameter, 0.50 and 0.32-0.52 for LAM thickness at the '9 o'clock position' and 0.55 and 0.33-0.45 for LAM thickness at the '3 o'clock position'. Both intra- and interobserver analysis revealed acceptable LOAs for hiatal measurements, but the LOAs were wide for thickness measurements. The correlation of LAM avulsion score was excellent on intra- and interobserver analysis. Antenatal mean ± SD LUGs were 18.8 ± 2.4 mm and 19.2 ± 2.3 mm on right and left sides, respectively; the intraobserver ICC was 0.82-0.91 but LOAs were wide, while interobserver ICC was 0.13-0.68 and also had wide LOAs.

CONCLUSIONS

3D-EVUS is a reliable tool for the assessment of hiatal measurements and LAM avulsion in women during pregnancy and after delivery, but performs less well for measurements of LAM thickness and LUG. EVUS can therefore be used in research studies involving childbirth and recurrent prolapse.

Assessment of a semiautomated pelvic floor measurement model for evaluating pelvic organ prolapse on MRI

INTRODUCTION AND HYPOTHESIS

The objective of this study was to assess the performance of a semiautomated pelvic floor measurement algorithmic model on dynamic magnetic resonance imaging (MRI) images compared with manual pelvic floor measurements for pelvic organ prolapse (POP) evaluation.

METHODS

We examined 15 MRIs along the midsagittal view. Five reference points used for pelvic floor measurements were identified both manually and using our semiautomated measurement model. The two processes were compared in terms of accuracy and precision.

RESULTS

The semiautomated pelvic floor measurement model provided highly consistent and accurate locations for all reference points on MRI. Results also showed that the model can identify the reference points faster than the manual-point identification process.

CONCLUSION

The semiautomated pelvic floor measurement model can be used to facilitate and improve the process of pelvic floor measurements on MRI. This will enable high throughput analysis of MRI data to improve the correlation analysis with clinical outcomes and potentially improve POP assessment.

Reliability of pelvic floor measurements on three- and four-dimensional ultrasound during and after first pregnancy: implications for training

OBJECTIVES

To evaluate the reliability of measurements of the levator hiatus and levator-urethra gap (LUG) using three/four-dimensional (3D/4D) transperineal ultrasound in women during their first pregnancy and 6 months postpartum, and to assess the learning process for these measurements.

METHODS

An inexperienced observer was taught to perform measurements of the levator hiatus and LUG by an experienced observer. After training, 3D/4D ultrasound volume datasets of 40 women in the first trimester were analyzed by these two observers. Another training session then took place and both observers repeated the analyses of the same volume datasets. Finally, analyses of 40 volume datasets of the women 6 months postpartum were performed by both observers. Intra- and interobserver reliability were determined by intraclass correlation coefficients (ICC) with 95% CIs.

RESULTS

For levator hiatal measurements, in the women during their first pregnancy the interobserver reliability was substantial to almost perfect after both the first and second training session (ICC, 0.62-0.83 and 0.71-0.89, respectively, for anteroposterior diameter, transverse diameter and area at rest, on contraction and on Valsalva) and the intraobserver reliability was substantial to almost perfect for both observers. For these measurements performed once the women had delivered, interobserver reliability was moderate to almost perfect. For LUG measurements performed during pregnancy, interobserver reliability was slight to moderate after the first training session (ICC, 0.14-0.54), but improved after the second training session (ICC, 0.38-0.71), and intraobserver reliability was moderate to substantial for the experienced observer and slight to moderate for the inexperienced observer. For these measurements performed when the women had delivered, interobserver reliability was fair to moderate.

CONCLUSIONS

The levator hiatus and LUG can be measured reliably using 3D/4D ultrasound in primigravid and primiparous women. The technique to measure dimensions of the levator hiatus requires limited teaching, but LUG measurements are more difficult and require more extensive training.

Female longitudinal anal muscles or conjoint longitudinal coats extend into the subcutaneous tissue along the vaginal vestibule: a histological study using human fetuses

PURPOSE

It is still unclear whether the longitudinal anal muscles or conjoint longitudinal coats (CLCs) are attached to the vagina, although such an attachment, if present, would appear to make an important contribution to the integrated supportive system of the female pelvic floor.

MATERIALS AND METHODS

Using immunohistochemistry for smooth muscle actin, we examined semiserial frontal sections of 1) eleven female late-stage fetuses at 28-37 weeks of gestation, 2) two female middle-stage fetus (2 specimens at 13 weeks), and, 3) six male fetuses at 12 and 37 weeks as a comparison of the morphology.

RESULTS

In late-stage female fetuses, the CLCs consistently (11/11) extended into the subcutaneous tissue along the vaginal vestibule on the anterior side of the external anal sphincter. Lateral to the CLCs, the external anal sphincter also extended anteriorly toward the vaginal side walls. The anterior part of the CLCs originated from the perimysium of the levator ani muscle without any contribution of the rectal longitudinal muscle layer. However, in 2 female middle-stage fetuses, smooth muscles along the vestibulum extended superiorly toward the levetor ani sling. In male fetuses, the CLCs were separated from another subcutaneous smooth muscle along the scrotal raphe (posterior parts of the dartos layer) by fatty tissue.

CONCLUSION

In terms of topographical anatomy, the female anterior CLCs are likely to correspond to the lateral extension of the perineal body (a bulky subcutaneous smooth muscle mass present in adult women), supporting the vaginal vestibule by transmission of force from the levator ani.

[An updated overview on the anatomy and function of the female pelvic floor, with emphasis on the effect of vaginal delivery]

Phylogenetically, the pelvic floor is a relatively old group of skeletal muscles which, along the acquisition of the erect posture by the human, gained a number of new important roles or were subjected to adaptation of some other roles performed earlier. The functional tasks of the pelvic floor in women (mostly of its prominent representatives - the levator ani muscles) include: supporting the contents of the abdominal cavity at the upright position, participation in the volitional and reflex compression of the urethra, narrowing the transverse dimension of the vagina and urogenital hiatus, involvement in sexual functions, and securing the terminal portion of the alimentary tract. The aim of this overview was to briefly review the information on the latest understanding of the anatomy of the pelvic floor, delineate its nomenclature recommended by the Federative Committee on Anatomical Terminology, and emphasize an array of physiological findings related to the contractility of these important muscles. The functional specialization of striated muscle fiber types and the anatomical basis of the relationship between vaginal delivery at term and postpartum urinary incontinence have been underlined. Nowadays, some intrapartum injuries to the pelvic floor can be successfully detected with ultrasound in the immediate postpartum period. This updated information should be part of a basic professional knowledge for obstetrician-gynecologist.

[Functional anatomy of the pelvic floor]

The pelvic floor is the support of the pelvic viscera. The levator ani muscle (LA) with its two bundles (pubo- and iliococcygeus) is the major component of this pelvic floor. LA is formed essentially by type I fibers (slow twitch, with high oxidative capability and presence of slow myosin) as in postural muscles. The aerobic metabolism makes LA fragile to excentric contraction and to mitochondrial dysfunction. The innervation of the pelvic floor comes from the 2nd, 3rd, 4th anterior sacral roots; denervation affects pelvic dynamism. Perineum includes the musculofascial structures under the LA: ventrally the striated sphincter of urethra and the ischiocavernosus and bulbospongiosus, caudally the fatty tissue filling the ischioanal fossa. Pelvic fascia covers the muscles ; it presents reinforcements : the uterosacral and cardinal ligaments, the arcus tendineus fascia pelvis (ATFP) and the arcus tendineus levator ani (ATLA). The pelvis statics is supported by the combined action of all this anatomical structures anteriorly forming the perineal "hammock," medially the uterosacral and cardinal ligaments, posteriorly the rectovaginal fascia and the perineal body. The angles formed by the pelvic viscera with their evacuation ducts participate to the pelvic statics. During the pelvic dynamics the modification of these angles expresses the action of the musculofascial structures.

Functional morphology of anal sphincter complex unveiled by high definition anal manometery and three dimensional ultrasound imaging

BACKGROUND

Anal sphincter complex consists of anatomically overlapping internal anal sphincter (IAS), external anal sphincter (EAS) and puborectalis muscle (PRM). We determined the functional morphology of anal sphincter muscles using high definition anal manometery (HDAM), three dimensional (3D)-ultrasound (US) and Magnetic resonance (MR) imaging.

METHODS

We studied 15 nulliparous women. High definition anal manometery probe equipped with 256 pressure transducers was used to measure the anal canal pressures at rest and squeeze. Lengths of IAS, PRM, and EAS were determined from the 3D-US images and superimposed on the HDAM plots. Movements of anorectal angle with squeeze were determined from the dynamic MR images.

KEY RESULTS

High definition anal manometery plots reveal that anal canal pressures are highly asymmetric in the axial and circumferential direction. Anal canal length determined by the 3D-US images is slightly smaller than that measured by HDAM. The EAS (1.9 ± 0.5 cm long) and PRM (1.7 ± 0.4 cm long) surround distal and proximal parts of the anal canal, respectively. With voluntary contraction, anal canal pressures increase in the proximal (PRM) and distal (EAS zone) parts of anal canal. Posterior peak pressure in the anal canal moves cranially in relation to the anterior peak pressure, with squeeze. Similar to the movement of peak posterior pressure, MR images show cranial movement of anorectal angle with squeeze.

CONCLUSIONS & INFERENCES

Our study proves that the PRM is responsible for the closure of the cranial part of anal canal. HDAM, in addition to measuring constrictor function can also record the elevator function of levator ani/pelvic floor muscles.

[The establishment and meaning of the three-dimensional finite element model of pelvic floor levator ani muscle in an old healthy woman]

This paper is to establish a three-dimensional finite element model (3D-FEM) of pelvic floor levator ani muscles in an old healthy women. We acquired the image data of the pelvic bones and pelvic floor muscles from CT and MRI scanning in a non-pregnant old healthy female volunteers. The 3-D reconstruction and mesh optimization of the whole pelvic bones and muscles with application of image processing software Mimics12.0 and Geomagic9.0 were obtained. Then we built the 3D-FEM of the musculoskeletal system of the pelvic bones and levator ani muscles with Ansys11.0 software. We obtained an accurate 3D-FEM of pelvic bones and levator ani muscles in the older healthy woman. The results showed that it was reliable to build 3D-FEM with CT and MRI scanning data and this model could vividly reflect the huge space anatomy of the real pelvic floor levator ani muscles. It avoids the defects to gain the model from the body of anatomical specimens in the past. The image data of model are closer to vivisection, and the model is more conducive to the latter finite element analysis.

Anatomy and histology of the lower urinary tract

The function of the lower urinary tract is basically storage of urine in the bladder and the at-will periodic evacuation of the stored urine. Urinary incontinence is one of the most common lower urinary tract disorders in adults, but especially in the elderly female. The urethra, its sphincters, and the pelvic floor are key structures in the achievement of continence, but their basic anatomy is little known and, to some extent, still incompletely understood. Because questions with respect to continence arise from human morbidity, but are often investigated in rodent animal models, we present findings in human and rodent anatomy and histology. Differences between males and females in the role that the pelvic floor plays in the maintenance of continence are described. Furthermore, we briefly describe the embryologic origin of ureters, bladder, and urethra, because the developmental origin of structures such as the vesicoureteral junction, the bladder trigone, and the penile urethra are often invoked to explain (clinical) observations. As the human pelvic floor has acquired features in evolution that are typical for a species with bipedal movement, we also compare the pelvic floor of humans with that of rodents to better understand the rodent (or any other quadruped, for that matter) as an experimental model species. The general conclusion is that the "Bauplan" is well conserved, even though its common features are sometimes difficult to discern.

Intrapartum translabial three-dimensional ultrasound visualization of levator trauma

OBJECTIVES

The aim of this study was to visualize levator trauma by three-dimensional (3D) ultrasound performed during labor and soon after the crowning of the fetal head and to determine how often levator trauma occurs.

METHODS

This was a prospective, observational study of 66 women enrolled during the first stage of labor. The women underwent intrapartum 3D transperineal ultrasound examination during the first and second stages of labor and within 12 h after delivery. Volume datasets were acquired and analyzed to determine the presence of levator trauma.

RESULTS

Data from 10 of the 66 women were excluded from analysis-nine because they underwent Cesarean section in the first or second stage of labor and one because she underwent hysterectomy and no postpartum volumes were collected. Thus our study group comprised 56 women-35 nulliparous and 21 parous. A total of 504 volumes were collected in the 56 women (three volumes for each stage of labor). One hundred and twenty levator volumes were excluded from analysis, but volumes of acceptable quality were available for all three stages of labor in all women. Eleven (31.4%) of the 35 nulliparae had levator lesions detected postpartum and none of them had levator lesions before delivery. Five (23.8%) of the 21 parous women had a levator tear detected in their postpartum volumes. In two of these five women the levator tear was also present in both volumes taken during labor.

CONCLUSIONS

Visualization of the levator ani during labor by 3D ultrasound examination is feasible. Comparison of volumes obtained during labor and within the first 2 h after delivery supports the theory that crowning of the head is the immediate cause of avulsion of the levator ani muscle.