Bilateral avulsion of the puborectal muscle: magnetic resonance imaging-based three-dimensional reconstruction and comparison with a model of a healthy nulliparous woman

Anal canal coronal-sagittal ratio: a novel parameter for diagnosing pelvic floor injury in two-dimensional transanal ultrasound

Purpose

Pelvic floor injury diagnosis using 3-dimensional (3D) pelvic floor ultrasound or magnetic resonance imaging is unfeasible in many clinics. We assessed the efficacy of a novel diagnostic parameter, the anal canal coronal-sagittal (CS) ratio, for pelvic floor injury on 2-dimensional [2D] transanal ultrasound.

Methods

This retrospective study analyzed the data of 126 female patients who underwent 3D pelvic floor ultrasound (including 2D transanal ultrasound) at a pelvic floor center between August and December 2020. The anal canal CS ratio on 2D transanal ultrasound and pelvic floor avulsion injury measurements were recorded for all patients.

Results

A cutoff anal canal CS ratio of 1.15 was obtained using receiver operating characteristic analysis (sensitivity, 0.820; specificity, 0.763; and area under the curve, 0.838). Patients were categorized into the anal canal CS ratio ≥1.15 and the anal canal CS ratio <1.15 groups. Bilateral pelvic floor avulsion was more common in the anal canal CS ratio ≥1.15 group (n=35, 56.5%), and the incidence of pelvic floor avulsion was significantly different between the 2 groups (P=0.001). Existing parameters of pelvic floor injury, including minimal levator hiatus (P=0.001), levator plate descent angle (P=0.001), and levator ani deficiency score (P=0.001), were statistically different between the 2 groups.

Conclusion

The anal canal CS ratio was an efficient novel parameter that indirectly detected pelvic floor injury in 2D transanal ultrasound. It is a potential alternative indicator for pelvic floor injury on the widely popular 2D transanal ultrasound.

Association between levator ani avulsion and urinary incontinence in women: A systematic review and meta-analysis

Background

Urinary incontinence is a bothersome symptom. Although the relationship between stress urinary incontinence (SUI) and vaginal delivery is established, the pathology underlying SUI after vaginal birth remains to be elucidated.

Objectives

To determine whether levator ani muscle avulsion predisposes for SUI in women.

Search strategy

Pubmed and Embase were searched for terms and their variations “levator ani muscle avulsion” and “urinary incontinence”, from inception until 5 November 2019.

Selection criteria

Inclusion criterion: studies describing the relationship between urinary incontinence and levator ani muscle avulsion in women at least 1 year after delivery. Exclusion criterion: studies only analyzing the urethral sphincter or hiatus dimensions.

Data collection and analysis

Odds ratios were used and if not available, were calculated as means of data synthesis, adjusted odds ratios if presented by the study, random‐effects model to compute a pooled estimate.

Results

Seven studies were included, accounting for 2388 women. Comparing women with and without levator ani muscle avulsion, the overall odds ratio for SUI is 0.87 (95% confidence interval 0.56–1.34), and after adjustment for possible confounders was 0.72 (95% confidence interval 0.40–1.30).

Conclusion

There is no relationship between levator ani muscle avulsion and SUI in women.

A systematic review and meta‐analysis was conducted to evaluate the relationship between levator ani muscle avulsion and stress urinary incontinence, which could not be supported.

Value of high-frequency two-dimensional ultrasound on evaluating puborectalis muscle

PURPOSE

To explore the value of high-frequency two-dimensional (2D) ultrasound on demonstrating the morphology of puborectalis muscle and detect muscle avulsion.

METHODS

High-frequency 2D ultrasound and tomographic ultrasound image (TUI) were peformed to demonstrate puborectalis muscle and detect muscle avulsion respectively among 158 women with or without significant pelvic organ prolapse (POP) (POP quantification grade 2 or higher). Mean values were compared using student's t test between women with or without avulsion defects. We performed Cohen's Kappa analysis to examine the test agreement between high-frequency 2D ultrasound and TUI mode. Pearson correlation analysis was performed to explore the relationship between the thickness of puborectalis muscle and the measurements of levator-urethra gap (LUG).

RESULTS

The result of high-frequency 2D ultrasound in detecting muscle avulsion agreed well with TUI mode (Kappa 0.88, P < 0.05). Women with muscle avulsion had thinner muscles and larger LUG measurements than those with normal muscle insertion (P < 0.05). Pearson correlation analysis revealed the negative relationship between the thickness of puborectalis muscle and LUG measurements (r = - 0.73).

CONCLUSION

The study confirmed that it was feasible to observe the morphology of puborectalis muscle and detect muscle avulsion by high-frequency 2D ultrasound.

Recommended standardized terminology of the anterior female pelvis based on a structured medical literature review

BACKGROUND

The use of imprecise and inaccurate terms leads to confusion amongst anatomists and medical professionals.

OBJECTIVE

We sought to create recommended standardized terminology to describe anatomic structures of the anterior female pelvis based on a structured review of published literature and selected text books.

STUDY DESIGN

We searched MEDLINE from its inception until May 2, 2016, using 11 medical subject heading terms to identify studies reporting on anterior female pelvic anatomy; any study type published in English was accepted. Nine textbooks were also included. We screened 12,264 abstracts, identifying 200 eligible studies along with 13 textbook chapters from which we extracted all pertinent anatomic terms.

RESULTS

In all, 67 unique structures in the anterior female pelvis were identified. A total of 59 of these have been previously recognized with accepted terms in Terminologia Anatomica, the international standard on anatomical terminology. We also identified and propose the adoption of 4 anatomic regional terms (lateral vaginal wall, pelvic sidewall, pelvic bones, and anterior compartment), and 2 structural terms not included in Terminologia Anatomica (vaginal sulcus and levator hiatus). In addition, we identified 2 controversial terms (pubourethral ligament and Grafenberg spot) that require additional research and consensus from the greater medical and scientific community prior to adoption or rejection of these terms.

CONCLUSION

We propose standardized terminology that should be used when discussing anatomic structures in the anterior female pelvis to help improve communication among researchers, clinicians, and surgeons.

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.

Paravaginal defect: A new classification of fascial and muscle tears in the paravaginal region

The lateral support of the vaginal wall depends on the integrity of the paravaginal section of the visceral pelvic fascia, levator ani, and their connection. Various defects of the muscle and fascia can result in identical clinical findings-ie, the descent of the lateral vaginal sulcus. In this study, we created a realistic scheme for classifying paravaginal defects, based on the complex relationship of the pelvic fascia with the levator ani. Surgical observations, cadaver examinations, and a complex magnetic resonance imaging (MRI)-based 3-dimensional (3D) model were used to analyze the spatial relationships of normal and defective anatomy of the female pelvic floor. Descent of the lateral vaginal sulcus can result from a defect in the paravaginal visceral pelvic fascia, levator ani, or both. The fascial defect can be partial or complete, and the muscle defect can vary in location. A detailed illustrated classification is presented. We present a new model of the pathology that underlies a common clinical finding.

Magnetic resonance imaging of the pelvic floor: from clinical to biomechanical imaging

This article reviews the current role of magnetic resonance imaging in the study of the pelvic floor anatomy and pelvic floor dysfunction. The application of static and dynamic magnetic resonance imaging in the clinical context and for biomechanical simulation modeling is assessed, and the main findings are summarized. Additionally, magnetic resonance-based diffusion tensor imaging is presented as a potential tool to evaluate muscle fiber morphology. In this article, focus is set on pelvic floor muscle damage related to urinary incontinence and pelvic organ prolapse, sometimes as a consequence of vaginal delivery. Modeling applications that evaluate anatomical and physiological properties of pelvic floor are presented to further illustrate their particular characteristics. Finally, finite element method is described as a method for modeling and analyzing pelvic floor structures' biomechanical performance, based on material and behavioral properties of the tissues, and considering pressure loads that mimic real-life conditions such as active contraction or Valsalva maneuver.

Is levator avulsion a predictor of cystocele recurrence following anterior vaginal mesh placement?

OBJECTIVE

Levator avulsion has been shown to be a predictor of cystocele recurrence following anterior colporrhaphy. The aim of this study was to determine if levator avulsion is a risk factor for prolapse recurrence following anterior colporrhaphy with mesh.

METHODS

This was a retrospective analysis of data obtained from three surgical audits for subjective and objective outcomes following anterior colporrhaphy with mesh. Recurrence was defined as cystocele ≥ Stage 2 on the prolapse quantification system of the International Continence Society; symptoms of vaginal lump/bulge; or cystocele on ultrasound, defined as maximum bladder descent to ≥ 10 mm below the symphysis pubis. Levator avulsion was diagnosed using tomographic ultrasound imaging.

RESULTS

Two hundred and nine patients were followed up at a mean of 2.2 years (range, 3 months to 5.6 years) after anterior vaginal mesh placement. 24% (51/209) had recurrent prolapse symptoms, 33% (68/209) clinical cystocele recurrence ≥ Stage 2, and 26% (54/209) a recurrent cystocele on ultrasound. Twenty-eight out of 80 (35%) women with levator avulsion had significant sonographic cystocele recurrence (odds ratio (OR), 2.24 (95% confidence interval (CI), 1.13-4.43)). This finding was confirmed after adjusting for potential predictors of prolapse recurrence on multivariate logistic regression (OR, 2.13 (95% CI, 1.04-4.39); P = 0.04).

CONCLUSION

Levator avulsion doubles the risk of cystocele recurrence after anterior colporrhaphy with transobturator mesh.

Pelvic floor trauma in childbirth

The investigation of female pelvic floor function and anatomy is moving from the fringes to the mainstream of urogynaecology and female urology, and it is becoming increasingly relevant for obstetrics. We are coming to realise that pelvic floor trauma in labour is common, usually overlooked, and a major factor in the causation of pelvic organ prolapse. Modern imaging methods such as magnetic resonance and 3D/4D ultrasound have enabled us to diagnose such trauma reliably and accurately, most commonly in the form of an avulsion of the puborectalis muscle; that is, a disconnection of the muscle from its insertion on the os pubis. Such damage to the levator muscle is macroscopically evident and can also be palpated, a skill that is available to every clinician, requiring neither investment nor specialised equipment. In this review, I will describe pelvic floor assessment by palpation and ultrasound and illustrate the commonest abnormalities and their clinical consequences. This paper will not focus on magnetic resonance imaging due to technical restrictions, cost and access issues in most jurisdictions, and because several papers have recently shown that ultrasound is at least as effective in diagnosing such trauma. Anal sphincter trauma is generally well covered in the literature and hence not subject of this review.

The effect of levator avulsion on hiatal dimension and function

OBJECTIVE

Pelvic floor trauma as a result of vaginal childbirth can cause significant pelvic floor morbidity. In this observational study, we intended to define whether such trauma is associated with abnormal hiatal biometry and/or abnormal biomechanical properties of the levator muscle.

STUDY DESIGN

The datasets of 414 urogynecologic patients were assessed in a retrospective study. Patients underwent an interview, clinical examination, and 3-/4-dimensional pelvic floor ultrasound. All analysis was performed offline using proprietary software. Hiatal dimensions and strain were measured.

RESULTS

In 21.1% of parous women with a history of vaginal delivery, an avulsion of the levator muscle was diagnosed, and in 8.6% it was bilateral. The relative risk of abnormal distensibility was 3.5 (95% confidence interval, 1.7-6.5) in unilateral and 3.96 (95% confidence interval, 1.7-9.2) in bilateral avulsion. Avulsion increased muscle distensibility on Valsalva and reduced muscle shortening on pelvic floor muscle contraction.

CONCLUSION

Avulsion injury is associated with abnormal levator biometry and function.

Fetal head circumference and length of second stage of labor are risk factors for levator ani muscle injury, diagnosed by 3-dimensional transperineal ultrasound in primiparous women

OBJECTIVE

We evaluated rate of levator ani muscle (LAM) avulsion among primiparae using 3-dimensional transperineal ultrasound to identify possible risk factors for such trauma.

STUDY DESIGN

We conducted a prospective observational study. Three-dimensional transperineal ultrasound was performed on all subjects. Primiparae were evaluated 24-72 hours after vaginal delivery. In all, 32 nulliparous gravidae (35-41 weeks) and 15 elective cesarean delivery primiparae were evaluated as methodological controls. We compared newborn head circumference (HC), birthweight, second stage duration, maternal age, baby sex, episiotomy, and instrumental delivery.

RESULTS

LAM trauma was observed in 39 of 210 (18.8%) patients and no controls. Odds ratio for LAM trauma when newborn HC >or= 35.5 cm was 3.343 (95% confidence interval, 1.33-8.42); when second stage duration >or= 110 minutes, odds ratio was 2.27 (95% confidence interval, 1.07-4.81). Logistic regression showed that HC >or= 35.5 and second stage duration >or= 110 minutes increased odds of LAM trauma by a factor of 5.32.

CONCLUSION

Large HC and prolonged second stage duration are risk factors in LAM trauma. Elective cesarean delivery may prevent LAM trauma.

PELVIC FLOOR ASSESSMENT

The topic of pelvic floor assessment is increasingly attracting attention from gynaecologists, colorectal surgeons, urologists and physiotherapists. This is not surprising, many women who have given birth naturally are affected by pelvic floor trauma, and so are their partners. Health professionals deal with the eventual consequences of such trauma, especially pelvic organ prolapse and faecal incontinence.

The levator-urethra gap measurement: a more objective means of determining levator avulsion?

OBJECTIVES

Levator avulsion, a common childbirth-related traumatic abnormality of this muscle, is characterized by a widened gap between the muscle insertion and urethra. This study assessed the use of four-dimensional ultrasound imaging to measure the levator-urethra gap (LUG) in order to identify avulsion.

METHODS

In a retrospective study, we reviewed the records of 118 women seen for clinical assessment and imaging. Axial plane tomographic ultrasound slices were obtained at intervals of 2.5 mm. The distance between the center of the urethra and the levator insertion was measured, blinded to clinical data, and the results were analyzed with reference to the diagnosis on palpation. An interobserver agreement analysis was conducted on 20 randomly selected patients included in the study.

RESULTS

A defect had been palpated in 19/116 women (16%) with complete datasets. LUG measurements were significantly higher in women who had been diagnosed with a levator avulsion on palpation (mean +/- SD, 27.6 +/- 6.7 mm vs. 19.7 +/- 3.4 mm; P < 0.001). The interobserver intraclass correlation coefficient for LUG measurement was good (0.71; 95% CI, 0.61-0.79). Receiver-operating characteristics analysis suggested a cut-off of 25 mm, with a sensitivity of 63% and a specificity of 94%, for the diagnosis of levator avulsion injury.

CONCLUSIONS

The measurement of LUG is reproducible and strongly associated with levator avulsion trauma diagnosed on vaginal palpation. A cut-off of 25 mm may be used for the diagnosis of levator avulsion injury.

Endopelvic fascia in women: shape and relation to parietal pelvic structures

OBJECTIVE

The endopelvic fascia is a confluent suspensory apparatus of the female pelvic organs. The aim of the study was to construct a three-dimensional model of the endopelvic fascia, defining its shape and its connections to the surrounding parietal structures.

METHODS

We created a three-dimensional multiple-source computer model to simultaneously visualize and analyze all the structures within the female pelvic floor. This model integrates data from magnetic resonance imaging of 15 nulliparas under age 30 with no symptoms of pelvic floor dysfunction. The model also includes data from direct observation in the dissection laboratory and in surgical rooms, together with the relevant scientific literature.

RESULTS

The endopelvic fascia has the shape of a semifrontally oriented septum, which surrounds the vagina and part of the uterine cervix and divides the pelvic floor into the anterior and posterior compartments. This confluent septum has specific connections to the pubic bone, anterior perineal membrane, perineal body, and superior fascia of the levator ani muscle. Additionally, the uterosacral part of the septum has three subdivisions- the "vascular part," the "neural part," and the true uterosacral ligament. Each of these subdivisions has a different physical link to the parietal structures. Three-dimensional illustrations and schemes were created to facilitate the understanding of the anatomy of these complex structures.

CONCLUSION

Connecting descriptions of the geometry of the organs visible by magnetic resonance imaging with descriptions of their individual connections to the endopelvic fascia gave us unique information about the three-dimensional representation of the anatomy of the female lesser pelvis. The endopelvic fascia divides the lesser pelvis in a manner that is similar to the way the urorectal septum divides the embryonic cloaca.

Validity and reproducibility of the digital detection of levator trauma

Levator ani muscle trauma is a common consequence of vaginal childbirth and detectable on digital vaginal palpation. To ascertain validity and reproducibility of this test, we saw 110 women for an interview, prolapse staging, digital vaginal palpation by two blinded examiners and four-dimensional translabial ultrasound. The mean age was 55.5 years (range 17-85) and the median parity was 2 (range 0-8). Three patients could not be assessed, leaving 107 datasets representing 214 assessments of a right or left puborectalis muscle. Levator defects were found in 21 women (20%) with nine bilateral defects. There was agreement between assessors in 173/214 (81%), k=0.411, signifying moderate agreement. Agreement with an independent blinded review of tomographic ultrasound data was k=0.495. Even after substantial training, the agreement between assessors using digital palpation for the diagnosis of levator trauma remains only moderate. There seems to be a substantial learning curve. Palpatory detection of major levator trauma is less repeatable than identification by ultrasound.

Three-dimensional transperineal ultrasonography of the pelvic floor: improving visualization for new clinical applications and better functional assessment

OBJECTIVE

With increasing awareness of the scope of pelvic floor disorders has come development and introduction into clinical practice of new imaging techniques, with increasing importance of ultrasonography. Complex pelvic floor anatomy, the conceptual difficulty in the basics of some pelvic floor disorders, and the uneven standardization of ultrasonographic techniques were the impetuses of this review. The purpose of this study was to review the basic anatomy of the pelvic floor and the transperineal ultrasonographic evaluation technique and to provide an overview of the current clinical use of 3-dimensional transperineal ultrasonography in the evaluation of the anterior and posterior pelvic floor compartments.

METHODS

A literature review illustrated with index cases from our center was conducted.

RESULTS

Ultrasonography has been widely applied to evaluation of the anterior and posterior compartments of the pelvic floor. Three-dimensional ultrasonography has a role in improving pelvic floor assessment.

CONCLUSIONS

Three-dimensional transperineal ultrasonography has been applied to evaluation of normal and pathologic pelvic floor anatomy. Practical application, through well-designed and sufficiently powered clinical studies, will establish the association between the clinical presentations of dysfunction with ultrasonographic findings.