Skeletal Muscle Complex Between the Vagina and Anal Canal: Implications for Perineal Laceration.

INTRODUCTION AND HYPOTHESIS: The anatomy of the skeletal muscles located between the vagina and anus is important during complex obstetric laceration reconstructions. We aimed to clarify the composition of skeletal muscles located between the vagina and anal canal and their three-dimensional configuration relevant to perineum repair. METHODS: This observational study involved ten female cadavers. An anatomical dissection was performed to observe the muscles around the vagina and anal canal. Immunohistological analysis of the midsagittal section was performed to clarify the composition of the muscles, and dissection was performed to correspond to the cross-section. Wide-range serial sectioning and three-dimensional reconstruction were used to support these findings histologically and visualize the three-dimensional arrangement. RESULTS: The region between the vagina and anal canal included the anterior part of the external anal sphincter, superficial transverse perineal muscle approaching from the lateral side, and levator ani, located cranially. They converge three-dimensionally in the median from each direction, forming a muscle complex between the vagina and anal canal. CONCLUSIONS: The medial region between the vagina and anal canal in those giving birth includes a skeletal muscle complex formed by the confluence of the external anal sphincter, anterior bundle of the levator ani, and superficial transverse perineal muscle. In cases of severe perineal lacerations, these muscles could be injured. The anatomical knowledge that a part of the levator ani forms a muscle sling anterior to the anal canal is particularly important for obstetricians and gynecologists repairing obstetric lacerations and treating pelvic floor disorders.

Postpartum Changes in Levator Plate Shape and Genital Hiatus Size After Vaginal Delivery.

INTRODUCTION AND HYPOTHESIS: Vaginal delivery is a risk factor for pelvic organ prolapse. We sought to quantify changes in level III pelvic support measurements at 7 weeks and 8 months following vaginal delivery. METHODS: This secondary analysis included primiparous women who underwent pelvic MRI and clinical examinations at 7 weeks and 8 months after vaginal delivery. Demographics and obstetrical data were abstracted. Mid-sagittal resting MRIs were used to perform level III measurements including urogenital hiatus (UGH), levator hiatus (LH), and mid-sagittal levator area (LA), and to trace the levator plate (LP). Using principal component analysis, 7-week and 8-month principal component scores (PC1s) and MRI measurements were compared using paired t test. If the PC1 score change from 7 weeks to 8 months was > 0, women were considered to have a more dorsally oriented LP shape. RESULTS: Of 76 participants, POP-Q values did not significantly differ between 7 weeks and 8 months, but MRI measurements improved (UGH: 3.9 ± 0.8 vs 3.5 ± 0.8, p < 0.001; LH: 5.4 ± 0.8 vs 5.2 ± 0.8, p = 0.01; LA: 18.0 ± 6.0 vs 15.2 ± 6.5, p < 0.001). Approximately 30% (22 out of 76) had a more dorsally oriented LP shape and larger level III measurements at 8 months than women with a more ventrally oriented LP shape (LA: 86.4% vs 1.9%, p < 0.001; LH: 16% vs 12%, p < 0.001; UGH: 59.1% vs 3.7%, p < 0.001). CONCLUSIONS: After vaginal delivery, most women had "recovery" of level III support-defined by smaller UGH, LH, and LA measurements-and a more ventrally oriented LP shape. However, nearly 30% had larger level III measurements and a more dorsally oriented LP shape, indicating "impaired recovery" of support.

Structural Changes in Brain White Matter Tracts Associated With Overactive Bladder Revealed by Diffusion Tensor Magnetic Resonance Imaging: Findings From a Symptoms of Lower Urinary Tract Dysfunction Research Network Cross-Sectional Case-Control Study.

PURPOSE: Our objective was to investigate structural changes in brain white matter tracts using diffusion tensor imaging (DTI) in patients with overactive bladder (OAB). MATERIALS AND METHODS: Treatment-seeking OAB patients and matched controls enrolled in the cross-sectional case-control LURN (Symptoms of Lower Urinary Tract Dysfunction Research Network) Neuroimaging Study received a brain DTI scan. Microstructural integrity of brain white matter was assessed using fractional anisotropy (FA) and mean diffusivity. OAB and urgency urinary incontinence (UUI) symptoms were assessed using the OAB Questionnaire Short-Form and International Consultation on Incontinence Questionnaire-Urinary Incontinence. The Lower Urinary Tract Symptoms Tool UUI questions and responses were correlated with FA values. RESULTS: Among 221 participants with evaluable DTI data, 146 had OAB (66 urinary urgency-only without UUI, 80 with UUI); 75 were controls. Compared with controls, participants with OAB showed decreased FA and increased mean diffusivity, representing greater microstructural abnormalities of brain white matter tracts among OAB participants. These abnormalities occurred in the corpus callosum, bilateral anterior thalamic radiation and superior longitudinal fasciculus tracts, and bilateral insula and parahippocampal region. Among participants with OAB, higher OAB Questionnaire Short-Form scores were associated with decreased FA in the left inferior fronto-occipital fasciculus, P < .0001. DTI differences between OAB and controls were driven by the urinary urgency-only (OAB-dry) but not the UUI (OAB-wet) subgroup. CONCLUSIONS: Abnormalities in microstructural integrity in specific brain white matter tracts were more frequent in OAB patients. More severe OAB symptoms were correlated with greater degree of microstructural abnormalities in brain white matter tracts in patients with OAB. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02485808.

Functional Anatomy of Urogenital Hiatus Closure: the Perineal Complex Triad Hypothesis.

INTRODUCTION: Urogenital hiatus enlargement is a critical factor associated with prolapse and operative failure. This study of the perineal complex was performed to understand how interactions among its three structures: the levator ani, perineal membrane, and perineal body-united by the vaginal fascia-work to maintain urogenital hiatus closure. METHODS: Magnetic resonance images from 30 healthy nulliparous women with 3D reconstruction of selected subjects were used to establish overall geometry. Connection points and lines of action were based on perineal dissection in 10 female cadavers (aged 22-86 years), cross sections of 4 female cadavers (aged 14-35 years), and histological sections (cadavers aged 16 and 21 years). RESULTS: The perineal membrane originates laterally from the ventral two thirds of the ischiopubic rami and attaches medially to the perineal body and vaginal wall. The levator ani attaches to the perineal membrane's cranial surface, vaginal fascia, and the perineal body. The levator line of action in 3D reconstruction is oriented so that the levator pulls the medial perineal membrane cranio-ventrally. In cadavers, simulated levator contraction and relaxation along this vector changes the length of the membrane and the antero-posterior diameter of the urogenital hiatus. Loss of the connection of the left and right perineal membranes through the perineal body results in diastasis of the levator and a widened hiatus, as well as a downward rotation of the perineal membrane. CONCLUSION: Interconnections involving the levator ani muscles, perineal membrane, perineal body, and vaginal fascia form the perineal complex surrounding the urogenital hiatus in an arrangement that maintains hiatal closure.

Pelvic floor injury during vaginal birth is life-altering and preventable: what can we do about it?

Pelvic floor disorders after childbirth have distressing lifelong consequences for women, requiring more than 300,000 women to have surgery annually. This represents approximately 10% of the 3 million women who give birth vaginally each year. Vaginal birth is the largest modifiable risk factor for prolapse, the pelvic floor disorder most strongly associated with birth, and is an important contributor to stress incontinence. These disorders require 10 times as many operations as anal sphincter injuries. Imaging shows that injuries of the levator ani muscle, perineal body, and membrane occur in up to 19% of primiparous women. During birth, the levator muscle and birth canal tissues must stretch to more than 3 times their original length; it is this overstretching that is responsible for the muscle tear visible on imaging rather than compression or neuropathy. The injury is present in 55% of women with prolapse later in life, with an odds ratio of 7.3, compared with women with normal support. In addition, levator damage can affect other aspects of hiatal closure, such as the perineal body and membrane. These injuries are associated with an enlarged urogenital hiatus, now known as antedate prolapse, and with prolapse surgery failure. Risk factors for levator injury are multifactorial and include forceps delivery, occiput posterior birth, older maternal age, long second stage of labor, and birthweight of >4000 g. Delivery with a vacuum device is associated with reduced levator damage. Other steps that might logically reduce injuries include manual rotation from occiput posterior to occiput anterior, slow gradual delivery, perineal massage or compresses, and early induction of labor, but these require study to document protection. In addition, teaching women to avoid pushing against a contracted levator muscle would likely decrease injury risk by decreasing tension on the vulnerable muscle origin. Providing care for women who have experienced difficult deliveries can be enhanced with early recognition, physical therapy, and attention to recovery. It is only right that women be made aware of these risks during pregnancy. Educating women on the long-term pelvic floor sequelae of childbirth should be performed antenatally so that they can be empowered to make informed decisions about management decisions during labor.

Dynamic analysis of the individual patterns of intakes, voids, and bladder sensations reported in bladder diaries collected in the LURN study.

The goal of this study was to develop the novel analytical approach and to perform an in-depth dynamic analysis of individual bladder diaries to inform which behavioral modifications would best reduce lower urinary tract symptoms, such as frequency and urgency. Three-day bladder diaries containing data on timing, volumes, and types of fluid intake, as well as timing, volumes, and bladder sensation at voids were analyzed for 197 participants with lower urinary tract symptoms. A novel dynamic analytic approach to bladder diary time series data was proposed and developed, including intra-subject correlations between time-varying variables: rates of intake, bladder filling rate, and urge growth rate. Grey-box models of bladder filling rate and multivariable linear regression models of urge growth rate were developed for individual diaries. These models revealed that bladder filling rate, rather than urine volume, was the primary determinant of urinary frequency and urgency growth rate in the majority of participants. Simulations performed with the developed models predicted that the most beneficial behavioral modifications to reduce the number of urgency episodes are those that smooth profiles of bladder filling rate, which might include behaviors such as exclusion of caffeine and alcohol and/or other measures, e.g., increasing number and decreasing volumes of intakes.

A unified pelvic floor conceptual model for studying morphological changes with prolapse, age, and parity.

Several 2-dimensional and 3-dimensional measurements have been used to assess changes in pelvic floor structures and shape. These include assessment of urogenital and levator hiatus dimensions, levator injury grade, levator bowl volume, and levator plate shape. We argue that each assessment reflects underlying changes in an individual aspect of the overall changes in muscle and fascial structures. Vaginal delivery, aging, and interindividual variations in anatomy combine to affect pelvic floor structures and their connections in different ways. To date, there is no unifying conceptual model that permits the evaluation of how these many measures relate to one another or that reflects overall pelvic floor structure and function. Therefore, this study aimed to describe a unified pelvic floor conceptual model to better understand how the aforementioned changes to the pelvic floor structures and their biomechanical interactions affect pelvic organ support with vaginal birth, prolapse, and age. In this model, the pelvic floor is composed of 5 key anatomic structures: the (1) pubovisceral, (2) puborectal, and (3) iliococcygeal muscles with their superficial and inferior fascia; (4) the perineal membrane or body; and (5) the anal sphincter complex. Schematically, these structures are considered to originate from pelvic sidewall structures and meet medially at important connection points that include the anal sphincter complex, perineal body, and anococcygeal raphe. The pubovisceral muscle contributes primarily to urogenital hiatus closure, whereas the puborectal muscle is mainly related to levator hiatus closure, although each muscle contributes to the other. Dorsally and laterally, the iliococcygeal muscle forms a shelflike structure in women with normal support that spans the remaining area between these medial muscles and attachments to the pelvic sidewall. Other features include the levator plate, bowl volume, and anorectal angle. The pelvic floor conceptual model integrates existing observations and points out evident knowledge gaps in how parturition, injury, disease, and aging can contribute to changes associated with pelvic floor function caused by the detachment of one or more important connection points or pubovisceral muscle failure.

Dynamic analysis of the individual patterns of intakes, voids, and bladder sensations reported in bladder diaries collected in the LURN study.

The goal of this study was to perform an in-depth dynamic analysis of individual bladder diaries to inform which behavioral modifications would best reduce lower urinary tract symptoms, such as frequency and urgency. Three-day bladder diaries containing data on timing, volumes, and types of fluid intake, as well as timing, volumes, and bladder sensation at voids were analyzed for 197 participants with lower urinary tract symptoms. A novel dynamic analytic approach to bladder diary time series data was proposed and developed, including intra-subject correlations between time-varying variables: rates of intake, bladder filling rate, and urge growth rate. Grey-box models of bladder filling rate and multivariable linear regression models of urge growth rate were developed for individual diaries. These models revealed that bladder filling rate, rather than urine volume, was the primary determinant of urinary frequency and urgency growth rate in the majority of participants. Simulations performed with the developed models predicted that the most beneficial behavioral modifications to reduce the number of urgency episodes are those that smooth profiles of bladder filling rate, which might include behaviors such as exclusion of caffeine and alcohol and/or other measures, e.g., increasing number and decreasing volumes of intakes.

Electrochemical Sensing of Urinary Chloride Ion Concentration for Near Real-Time Monitoring.

Urinary chloride concentration is a valuable health metric that can aid in the early detection of serious conditions, such as acid base disorders, acute heart failure, and incidences of acute renal failure in the intensive care unit. Physiologically, urinary chloride levels frequently change and are difficult to measure, involving time-consuming and inconvenient lab testing. Thus, near real-time simple sensors are needed to quickly provide actionable data to inform diagnostic and treatment decisions that affect health outcomes. Here, we introduce a chronopotentiometric sensor that utilizes commercially available screen-printed electrodes to accurately quantify clinically relevant chloride concentrations (5-250 mM) in seconds, with no added reagents or electrode surface modification. Initially, the sensor's performance was optimized through the proper selection of current density at a specific chloride concentration, using electrical response data in conjunction with scanning electron microscopy. We developed a unique swept current density algorithm to resolve the entire clinically relevant chloride concentration range, and the chloride sensors can be reliably reused for chloride concentrations less than 50 mM. Lastly, we explored the impact of pH, temperature, conductivity, and additional ions (i.e., artificial urine) on the sensor signal, in order to determine sensor feasibility in complex biological samples. This study provides a path for further development of a portable, near real-time sensor for the quantification of urinary chloride.

A comparison of MRI-based pelvic floor support measures between young and old women with prolapse.

INTRODUCTION AND HYPOTHESIS: We sought to 1) test the hypothesis that young women (≤45 years) with pelvic organ prolapse have a higher prevalence of major levator ani muscle (LAM) defects than old women (≥70 years) with prolapse and 2) compare level II/III measurements between young and old women with prolapse and age-matched controls to evaluate age-related mechanistic differences in the disease process. METHODS: A secondary analysis examined four groups of parous women: young prolapse (YPOP, n = 17); old prolapse (OPOP, n = 17); young controls (YC, n = 15); old controls, (OC, n = 13). Prolapse was defined as any compartment at or beyond the hymen with vaginal bulge symptoms. Genital hiatus (GH) was measured on clinical exam. Major LAM defects and level II/III measurements (UGH: urogenital hiatus, LA: levator area, and apex location) were assessed on MRI at rest and strain, and the difference (Δ) between measurements calculated. Principal component analysis was used to evaluate levator plate (LP) shape. RESULTS: Major LAM defects occurred in 42% of YPOP and 47% of OPOP (p > .99). GHrest was 1.5 cm larger in OPOP versus YPOP (p < .001) and 2 cm larger in OPOP versus OC (p < .001). Regardless of prolapse status, LArest and UGHrest on MRI increased with age. YPOP had larger ΔLA (p = .04), ΔUGH (p = .03), and Δapex than OPOP (p = .01). Resting LP shape was more dorsally oriented in OPOP versus YPOP (p = .02) and OC versus YC (p = .004). CONCLUSIONS: Prolapse in young women cannot be solely explained by a higher LAM defect prevalence. GH size and other measures of level II/III pelvic support worsen with age regardless of prolapse status.

Variations in structural support site failure patterns by prolapse size on stress 3D MRI.

INTRODUCTION AND HYPOTHESIS: Our objective was to develop a standardized measurement system to evaluate structural support site failures among women with anterior vaginal wall-predominant prolapse according to increasing prolapse size using stress three-dimensional (3D) magnetic resonance imaging (MRI). METHODS: Ninety-one women with anterior vaginal wall-predominant prolapse and uterus in situ who had undergone research stress 3D MRI were included for analysis. The vaginal wall length and width, apex and paravaginal locations, urogenital hiatus diameter, and prolapse size were measured at maximal Valsalva on MRI. Subject measurements were compared to established measurements in 30 normal controls without prolapse using a standardized z-score measurement system. A z-score greater than 1.28, or the 90th percentile in controls, was considered abnormal. The frequency and severity of structural support site failure was analyzed based on tertiles of prolapse size. RESULTS: Substantial variability in support site failure pattern and severity was identified, even between women with the same stage and similar size prolapse. Overall, the most common failed support sites were straining hiatal diameter (91%) and paravaginal location (92%), followed by apical location (82%). Impairment severity z-score was highest for hiatal diameter (3.56) and lowest for vaginal width (1.40). An increase in impairment severity z-score was observed with increasing prolapse size among all support sites across all three prolapse size tertiles (p < 0.01 for all). CONCLUSIONS: We identified substantial variation in support site failure patterns among women with different degrees of anterior vaginal wall prolapse using a novel standardized framework that quantifies the number, severity, and location of structural support site failures.

Comparison of in vivo visco-hyperelastic properties of uterine suspensory tissue in women with and without pelvic organ prolapse.

The uterine suspensory tissue (UST) complex includes the cardinal (CL) and uterosacral "ligaments" (USL), which are mesentery-like structures that play a role in resisting pelvic organ prolapse (POP). Since there is no information on the time-dependent material properties of the whole structure in situ and in vivo, we developed and tested an intraoperative technique to quantify in vivo whether there is a significant difference in visco-hyperelastic behavior of the CL and USL between women with and without POP. Thirteen women with POP (cases) and four controls scheduled for surgery were selected from an ongoing POP study. Immediately prior to surgery, a computer-controlled linear servo-actuator with a series force transducer applied a continuous, caudally directed traction force while simultaneously recording the resulting cervical displacement in the same direction. After applying an initial 1.1 N preload, a ramp rate of 4 mm/s was used to apply a maximum force of 17.8 N in three "ramp-and-hold" test trials. A simplified bilateral four-cable biomechanical model was used to identify the material behavior of each ligament. For this, the initial cross-section areas of the CL and USL were measured on 3-T magnetic resonance image-based 3D models from each subject. The time-dependent strain energy function of CL/USL was defined with a three-parameter hyperelastic Mooney-Rivlin material model and a two-term Prony series in relaxation form. When cases were compared with controls, the estimated time-dependent material constants of CL and USL did not differ significantly. These are the first measurements that compare the in vivo and in situ visco-hyperelastic response of the tissues comprising the CL and USL to loading in women with and without prolapse. Larger sample sizes would help improve the precision of intergroup differences.

Hiatal failure: effects of pregnancy, delivery, and pelvic floor disorders on level III factors.

INTRODUCTION AND HYPOTHESIS: The failure of the levator hiatus (LH) and urogenital hiatus (UGH) to remain closed is not only associated with pelvic floor disorders, but also contributes to recurrence after surgical repair. Pregnancy and vaginal birth are key events affecting this closure. An understanding of normal and failed hiatal closure is necessary to understand, manage, and prevent pelvic floor disorders. METHODS: This narrative review was conducted by applying the keywords "levator hiatus" OR "genital hiatus" OR "urogenital hiatus" in PubMed. Articles that reported hiatal size related to pelvic floor disorders and pregnancy were chosen. Weighted averages for hiatal size were calculated for each clinical situation. RESULTS: Women with prolapse have a 22% and 30% larger LH area measured by ultrasound at rest and during Valsalva than parous women with normal support. Women with persistently enlarged UGH have 2-3 times higher postoperative failure rates after surgery for prolapse. During pregnancy, the LH area at Valsalva increases by 29% from the first to the third trimester in preparation for childbirth. The enlarged postpartum hiatus recovers over time, but does not return to nulliparous size after vaginal birth. Levator muscle injury during vaginal birth, especially forceps-assisted, is associated with increases in hiatal size; however, it only explains a portion of hiatus variation-the rest can be explained by pelvic muscle function and possibly injury to other level III structures. CONCLUSIONS: Failed hiatal closure is strongly related to pelvic floor disorders. Vaginal birth and levator injury are primary factors affecting this important mechanism.

Natural history of lower urinary tract symptoms in treatment-seeking women with pelvic organ prolapse; the Symptoms of Lower Urinary Tract Dysfunction Research Network (LURN).

BACKGROUND: The association of pelvic organ prolapse with overactive bladder and other lower urinary tract symptoms, and the natural history of those symptoms are not well characterized. Previous cross-sectional studies demonstrated conflicting relationships between prolapse and lower urinary tract symptoms. OBJECTIVE: This study primarily aimed to determine the baseline association between lower urinary tract symptoms and prolapse and to assess longitudinal differences in symptoms over 12 months in women with and without prolapse. Secondary aims were to explore associations between lower urinary tract symptoms and prolapse treatment. We hypothesized that: (1) prolapse is associated with the presence of lower urinary tract symptoms, (2) lower urinary tract symptoms are stable over time in patients with and without prolapse, and (3) prolapse treatment is associated with lower urinary tract symptom improvement. STUDY DESIGN: Women enrolled in the Symptoms of Lower Urinary Tract Dysfunction Research Network Observational Cohort Study with adequate 12-month follow-up data were included. Prolapse and lower urinary tract symptom treatment during follow-up was guided by standard of care. Outcome measures included the Lower Urinary Tract Symptoms Tool total severity score (in addition to overactive bladder, obstructive, and stress urinary incontinence subscales) and Urogenital Distress Inventory-6 Short Form. Prolapse (yes or no) was defined primarily when Pelvic Organ Prolapse Quantification System points Ba, C or Bp were >0 (beyond the hymen). Mixed-effects models with random effects for patient slopes and intercepts were fitted for each lower urinary tract symptom outcome and prolapse predictor, adjusted for other covariates. The study had >90% power to detect differences as small as 0.4 standard deviation for less prevalent group comparisons (eg, prolapse vs not). RESULTS: A total of 371 women were analyzed, including 313 (84%) with no prolapse and 58 (16%) with prolapse. Women with prolapse were older (64.6±8.8 vs 55.3±14.1 years; P<.001) and more likely to have prolapse surgery (28% vs 1%; P<.001) and pessary treatment (26% vs 4%; P<.001) during the study. Average baseline Lower Urinary Tract Symptoms Tool total severity scores were lower (fewer symptoms) for participants with prolapse compared with those without (38.9±14.0 vs 43.2±14.0; P=.036), but there were no differences in average scores between prolapse groups for other scales. For all urinary outcomes, average scores were significantly lower (improved) at 3 and 12 months compared with baseline (all P<.05). In mixed-effects models, there were no statistically significant interactions between pelvic organ prolapse measurement and visit and time-dependent prolapse treatment groups (P>.05 for all regression interaction coefficients). The Lower Urinary Tract Symptoms Tool obstructive severity score had a statistically significant positive association with Pelvic Organ Prolapse Quantification System Ba, Bp, and point of maximum vaginal descent. The Lower Urinary Tract Symptoms Tool total severity scale had a statistically significant negative association with Pelvic Organ Prolapse Quantification System Ba and point of maximum vaginal descent. No other associations between prolapse and lower urinary tract symptoms were significant (P>.05 for all regression coefficients). Symptom differences between prolapse groups were small: all regression coefficients (interpretable as additive percentage change in each score) were between -5 and 5 (standard deviation of outcomes ranged from 14.0-32.4). CONCLUSION: Among treatment-seeking women with urinary symptoms, obstructive symptoms were positively associated with prolapse, and overall lower urinary tract symptom severity was negatively associated with prolapse. Lower Urinary Tract Symptoms Tool scores improved over 12 months regardless of prolapse status, including in those with treated prolapse, untreated prolapse, and without prolapse.