Failure of the urogenital hiatus to remain closed in women is a major contributor to prolapse operation failure and development of prolapse after childbirth. This article presents a conceptual framework, the Urogenital Hiatus Closure System (UHCS), that explains how anatomic and neuromuscular elements interact to maintain, or fail to maintain, hiatal closure. Clinical observations demonstrate that no single structure reliably predicts hiatus size; instead, hiatal behavior results from the integrated functional components. The UHCS has three primary elements: the levator ani muscle, neuromotor control, and Level III connective tissues of the perineal complex-each of which can be injured, partially compensated, or overloaded. These structures form a neuromechanically integrated unit in which the medial levator ani, the perineal membrane and its central connection, and the afferent-efferent control loops work to provide resting tone, active contraction, resistance to dilation, and spatial alignment. A principle of the model is redundancy: failure in one component may not enlarge the hiatus, but combinations of failures exceed compensatory capacity and result in failure. It links Level III mechanics to Level I-II support by demonstrating how an open hiatus increases forces on apical and paravaginal tissues, driving a feed-forward cycle of prolapse dilation and muscle elongation. Conceptually, the UHCS is an interacting triad influenced by functional modifiers-loading conditions, prolapse effects, muscle length, motor activation, and connective-tissue properties-that determine hiatus size. This systems-based approach can guide classification of failure patterns to inform biomechanical, anatomical, and therapeutic research.

The perineal membrane (PM), perineal body, and levator ani muscles form the perineal complex, which is responsible for hiatal closure. Yet failures in its connective tissues that may lead to hiatal closure impairment are poorly understood. We tested the hypothesis that pelvic organ prolapse involves PM abnormalities by comparing PM morphology between young women with prolapse and parous controls using a validated MRI-based reconstruction and analysis technique. This is a secondary analysis of MRIs from two prior studies. The PM was traced on coronal scans in 3D Slicer®, and surface models were analyzed using Rhino®. Six PM parameters were measured: swinging door angle, visible bony origin length, hiatal anteroposterior diameter and area, PM surface area, and midline separation. Group comparisons used t tests, with Cohen’s d, correlations, and stepwise regression analysis. Resting MRIs from 17 young parous women (aged < 40 years) with prolapse and 20 parous controls were compared. Women with prolapse showed 23

Purpose:To document the logistics and technical considerations of a multi-center protocol evaluating the sensory and motor function of both the bladder and the urethra, in women with urgency only, urinary urgency with incontinence, and controls. Methods:The study network organization and infrastructure are described, with attention to the technical training methods and continuous data quality control. Results:The LURN Organ study was approved in March 2020 and enrolled participants from March 2021 - November 2023, through the COVID pandemic. One hundred five participants were enrolled from all 6 research sites and completed the study testing protocol with no adverse events. All participants had evaluable data, and the majority of the participants had evaluable data from all 4 lower urinary tract (LUT) tests of the protocol. One test cohort did not reach the target enrollment adequate for statistical analysis. The lessons of a pilot study and technical practice; virtual training for a LUT physiology study; early, continuous technical and data quality control; diverse expertise within the research team, and under-enrollment in one cohort are discussed. Conclusions:The conduct of a large, multi-site extended lower urinary tract physiology study is necessarily complex, resource-intensive, and fraught with possible pitfalls. The lessons learned by the LURN-Organ study group, particularly in the context of unprecedented circumstances, will hopefully help and inspire future investigators to continue this much-needed clinical research in LUT function.

Although vaginal birth has the highest risk of musculoskeletal injury per hour of exposure of any natural human activity, the resulting injuries often go unrecognized - sometimes for decades. The types of tissues injured during a difficult vaginal birth are similar to those involved in other musculoskeletal injuries. It is not widely appreciated that multiple structures can be injured, including pubic bone stress fractures, injury to the nerve innervating the right or left levator ani (LA) muscle, stretch injuries of the LA muscles themselves, and/or passive tissue stretch injuries to the perineal body (PB), perineal membrane (PM), and endopelvic fascia. Complicating the issue further is the possibility that each structure can be injured to differing extents, and the injuries can occur in a variety of combinations. As a contribution to the existing literature, the relevant information is tabulated for the first time in a pelvic floor musculoskeletal injury classification system, supported by illustrations for easy reference. Because early identification and interventions can help reduce, and even prevent, long-term symptoms, it is important to screen postpartum athletes and refer them to pelvic health specialists when appropriate. This will help benefit these athletes by fostering appropriate interdisciplinary collaboration with their sports medicine care team.

This paper describes a novel wearable personal uroflowmeter and its use to log urine leakage episodes in women. Consisting of a miniature flow rate sensor attached under the urethral meatus, it recorded both urine flow rate and volume during activities of daily living. The sensor communicated with a determining unit incorporating a microcontroller and an inertial measurement unit worn at the waist, facilitating the post-hoc determination of which activities and changes in pose caused leakage. Six women participated in a feasibility study performed in a clinical setting. The results indicate that the uroflowmeter was 97.5% accurate in assessing micturition flow compared to gold standard uroflowmetry and leakage measurements. The system also provides subject-specific information on the relationship between physical activity and urine leakage, thereby eliminating errors due to missing data and recall bias in bladder leakage diaries and circumventing the limitations of office-based uroflowmeters.

OBJECTIVE:To identify morphological features of the soft tissue and bony pelvis that could serve as predictive risk factors for the development of pelvic organ prolapse (POP) in adult women. METHODS:This case-control study compared the shapes of the pelvic floor soft tissue and bony pelvis between three groups: parous women with POP (cases); parous women without symptoms of POP (controls); and nulliparous women. The primary dataset comprised 21 women around 50 years of age (mean ± SD, 50.3 ± 1.3 years), with seven participants in each group. Landmarks on the pelvis and urogenital hiatus were collected on magnetic resonance imaging scans. Pelvic shape was analyzed using geometric morphometry and principal component analysis. The findings were validated in a small secondary dataset of four parous women in their 30s, of whom two had POP and two were controls. RESULTS:Significant differences were observed between cases, controls and nulliparae in the primary dataset when soft tissue shape and pelvic shape were analyzed together on principal component analysis. When the shape of the bony pelvis was considered alone, a significant difference was observed between cases and controls, with the former group exhibiting a mediolaterally wider pelvis with relatively short anteroposterior and craniocaudal diameters. This difference was generalizable to younger women in the secondary dataset. CONCLUSION:The shape of the pelvis in adult women affects their risk for postpartum POP. © 2025 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

BACKGROUND: A large urogenital hiatus in level III results in a higher risk of developing pelvic organ prolapse after birth and failure after prolapse surgery. Deepening of the pelvic floor and downward rotation of the levator plate have also been linked to prolapse. Currently we lack data that evaluates how these measures relate to one another and to prolapse occurrence and size. OBJECTIVE: This study uses measurements from a published conceptual model to compare women with and without prolapse to determine the magnitude of difference between cases and controls and to quantify the interrelationships among different aspects of pelvic floor shape and structure. STUDY DESIGN: Ninety-one women with anterior predominant prolapse and uterus in situ who had 3D MRI and 30 similar women with normal support were studied. Resting scans were used to avoid the influence of the prolapse dilating the hiatus. Measurements assessed 3 domains: hiatus size (urogenital and levator hiatus); length of the surrounding pelvic floor muscles (pubovisceral, puborectal, iliococcygeal muscles); the shelf-like posterior pelvic floor (leva tor plate shape, levator bowl volume), and bony pelvic dimensions. Effect sizes were calculated and principal component shape analysis performed to evaluate levator plate shape. z scores were calculated and a value greater than 1.68 (95th percentile) was considered the "failure" criterion. Frequency and severity of structural support site failure were analyzed by prolapse size. RESULTS: Resting urogenital and levator hiatal areas were 68% and 59% larger in the prolapse group compared to controls. These area enlargements were 2 to 4 times larger than the anterior-posterior dimension enlargements (urogenital hiatus 36%; levator hiatus 13%). The greatest muscle length differences between groups occurred in the pubovisceral (34%) and puborectal (25%) muscles compared to the iliococcygeal muscle (8%)-roughly half the area differences. Levator bowl volume was 63% deeper with prolapse. Urogenital hiatus and levator hiatus areas were strongly correlated with pubovisceral and puborectal muscle length (0.7-0.8), while iliococcygeal muscle length had lower correlations (0.4-0.5). Levator bowl volume correlated strongly with hiatal enlargement (0.7-0.8) and muscle length (pubovisceral and puborectal muscles), moderately so with levator plate and iliococcygeal muscle, and weakly with bony dimension. Failure frequency increased with prolapse size for urogenital hiatus anterior-posterior (P=.001) and area (P=.019). By contrast, levator hiatus area was similar for all prolapse sizes (P=.288), while levator hiatus anterior-posterior failure was more common in larger prolapses (P=.018) but with smaller percentages of failure than levator hiatus area (P<.01). Both levator bowl volume (P=.015) and levator plate (P=.045) trended toward increasing failure with larger prolapse sizes. Among women with enlarged urogenital hiatus at straining, 43% and 28% had normal urogenital hiatus anterior-posterior and area at rest, respectively. CONCLUSION: Changes in the shape and dimensions of the pelvic floor are complex and are not captured by a single measure (such as the urogenital hiatus anterior-posterior dimension, which does not capture its lateral expansion). The failure patterns were different between small and large prolapses. Understanding why could lead to improved prevention and treatments for level III failures.

Background: The lower birth canal is the final constriction through which a fetal head must pass for delivery. Unfortunately, injuries to the lower birth canal tissues occur in up to 19 % of first-time vaginal deliveries due to the 300 % stretch required. Methods: This is a secondary analysis of data from 56 healthy nullipara recorded by a lower birth canal dilator during the first stage of labor. A four parameter Fractional Zener rheological Model was used to characterize the canal viscoelastic properties during the first stage of labor. We tested the (null) hypothesis that the Model constants identified during the initial 20 s ramp-and-5-min-hold dilation from 40 to 55 mm will not accurately predict the final hoop tension after 60 min of slower dilation. Findings: The null hypothesis was rejected in that when the four Model parameters were calculated for all nullipara from the 20-s-ramp-and-5-min-hold data, the relative fit error was 8 f 4 %, and the relative prediction error after 60 min of dilation was 10 f 5 %. Furthermore, when the Model constants were instead calculated from the 20 s ramp and only the initial 90 s of the 5-min-hold, the error was still acceptable: 13 f 4 % for relative fit and 13 f 18 % for relative prediction. Interpretation: Two minutes is sufficient to characterize canal viscoelastic properties during the first stage of labor and identify those with stiffer tissues at higher risk for a pelvic floor injury during delivery. This could form the basis for a clinical test predicting injury.

BACKGROUND:Accurately outlining ("segmenting") pelvic organs from magnetic resonance imaging scans is crucial for studying pelvic organ prolapse. The labor-intensive process of segmentation that identifies which pixels correspond to a particular organ in magnetic resonance imaging datasets imposes a substantial bottleneck on training artificial intelligence to do automated segmentation techniques, underscoring a need for methods that can operate effectively with minimal prelabeled data. OBJECTIVE:The aim of this study is to introduce a novel semi-supervised learning process that uses limited data annotation in pelvic magnetic resonance imaging to improve automated segmentation. By effectively using both labeled and unlabeled magnetic resonance imaging data, our approach seeks to improve the accuracy and efficiency of pelvic organ segmentation, thereby reducing the reliance on extensive labeled datasets for artificial intelligence model training. STUDY DESIGN:The study used a semi-supervised deep learning framework for uterus and bladder segmentation, in which a model is trained using both a small number of expert-outlined structures and a large number of unlabeled scans, leveraging the information from the labeled data to guide the model and improve its predictions on the unlabeled data. It involved 4103 magnetic resonance images from 48 female subjects. This approach included self-supervised learning of image restoration tasks for feature extraction and pseudo-label generation, followed by combined supervised learning on labeled images and unsupervised training on unlabeled images. The method's performance was evaluated quantitatively using the Dice Similarity Coefficient, Average Surface Distance, and 95% Hausdorff Distance. For statistical analysis, 2-tailed paired t-tests were conducted for comparison. RESULTS:This framework demonstrated the capacity to achieve segmentation accuracy comparable to traditional methods while requiring only about 60% of the typically necessary labeled data. Specifically, the semi-supervised approach achieved Dice Similarity Coefficients of 0.84±0.04, Average Surface Distances of 13.98±0.93, and 95% Hausdorff Distances of 2.15±0.40 for the uterus and 0.92±0.05, 2.51±0.83, and 2.88±0.17 for the bladder, respectively (P value <.001 for all), outperforming both the baseline supervised learning and transfer learning models. Additionally, 3-dimensional reconstructions using the semi-supervised method exhibited superior details in the visualized organs. CONCLUSION:This study's semi-supervised learning framework wherein the full use of unlabeled data markedly reduces the necessity for extensive manual annotations, achieving high segmentation accuracy with substantially fewer labeled images that can enhance clinical evaluation and advance medical image analysis by reducing the dependency on large-scale labeled pelvic magnetic resonance imaging datasets for training.

Vaginal pessaries are a cost-effective, nonsurgical treatment for pelvic organ prolapse (POP), but limited understanding of pessary biomechanics and the inability of static MRI analyses to capture continuous device–tissue interactions hinder design innovation. While dynamic magnetic resonance imaging (MRI) offers insights into pelvic floor biomechanics, conventional analyses rely on static frame comparisons and cannot capture continuous device–tissue interactions. This study aimed to apply a validated, automated motion-tracking framework to dynamic MRI for frame-by-frame analysis of pessary kinematics and evaluate correlations between pessary displacement and changes in hiatus dimensions. In this prospective pilot study, six individuals with anterior vaginal wall-predominant POP successfully using a ring pessary with support underwent dynamic 3D pelvic MRI at rest and during maximal Valsalva. A previously validated optical flow-based tracking algorithm was employed to quantify frame-by-frame motion of defined mid-sagittal regions of interest (ROIs), including pessary rims, perineal body, and anorectal angle. These regions of interest were chosen for their biomechanical relevance in capturing the interaction between the pessary and the structures that define the urogenital and levator hiatus size, key determinants of pessary retention. Pearson correlation was used to evaluate the relationship between distal pessary displacement and changes in urogenital and levator hiatus dimensions. The median age was 66.5 years (range 52–76) and median pessary use was 3 years (range 2–4); all patients used a size 3 or 4 ring pessary and performed self-maintenance. Two of six reported occasional prolapse of the pessary, and all achieved successful retention. Resting MRI showed the pessary positioned posterior and inferior to the pubic bone with elevation of both anterior and posterior vaginal walls in all patients, as compared to resting MRI without the pessary in situ. Automated tracking was successful for all participants. Frame-by-frame analysis demonstrated strong correlations between distal pessary translation and enlargement of the urogenital hiatus (r = 0.96 [95

An enlarged urogenital hiatus is as important as apical support or fascial attachment failures in the development of prolapse and is strongly related to operative failure, yet we lack a conceptual model for factors responsible for hiatal failure. For a conceptual model to be valid, it cannot be proven false by empirical observation. We present six clinical observations with which future model development must be consistent. (1) Perineal body damage alone does not explain an enlarged urogenital hiatus. Three women have complete 4th degree lacerations but small hiatuses. (2) Levator damage is not a sole causal factor. One woman has bilateral levator avulsion but a normal hiatus, while another has intact muscles and an enlarged hiatus. (3) Hiatal assessment during straining is incomplete. Two women with similar straining urogenital hiatuses of 6-7 cm have respective 1.5 cm and 7 cm resting hiatuses. (4) Urogenital hiatus measurements during straining are confounded by Valsalva effort strength. Urogenital hiatus size increases by 30%, 51%, and 181% in one woman depending on straining strength. (5) Hiatal closure during pelvic muscle contraction differs widely. One woman can close her hiatus from 3.5 cm to 1.5 cm, while another shows no reduction despite evidence of contraction. (6) Prolapse/hiatus interactions occur with advancing age. One woman experiences progressive hiatal enlargement over 31 years. Our clinical observations reveal the complexity of the multiple factors involved in hiatal failure and support the need for a unified disease model consistent with these factors on which to base future research.

PURPOSE:To investigate sensory and motor function of the bladder and urethra in women with and without urgency urinary incontinence (UUI). MATERIALS AND METHODS:Treatment-seeking women with UUI and healthy, asymptomatic, nontreatment seeking controls enrolled in the Symptoms of Lower Urinary Tract Dysfunction Research Network Organ-Based study (LURN-Organ) and underwent a single session of physiological testing. Testing included rapid-fill cystometry before and after lidocaine administration, urethral pressure profiles, pelvic floor contraction (Kegel) testing, and tuning fork sensation testing at the urethral meatus. RESULTS:Data were collected from 31 asymptomatic controls and 56 women with UUI. Women with UUI were more likely to demonstrate detrusor overactivity (DO) (32% vs. 10% in controls, p = 0.019). In addition, women with UUI on average generated 25% lower active urethral closure pressures during maximal contraction (p = 0.0016) and reported sensations at lower volumes during cystometry (34% lower for first desire to void, p = 0.028; 34% lower for strong desire to void, p = 0.0017; and 32% lower for maximum cystometric capacity, p = 0.0047). Women with UUI demonstrated diminished urethral sensation on the tuning fork test (median of 7 vs. 8 in controls) though the difference was not significant (p = 0.054). Considerable overlap in all findings occurred between cases and controls in each parameter. While individual component comparisons revealed some differences, additional multivariable analysis demonstrated prominently the physiological heterogeneity of women with UUI. CONCLUSIONS:Women with UUI demonstrated varying amounts of bladder sensory dysfunction, urethral motor dysfunction and bladder motor dysfunction. Considering the function of lower urinary tract components in combination may reveal UUI phenotypes, highlighting the need to study UUI from a multifactorial perspective. CLINICAL TRIAL REGISTRATION:ClinicalTrials.gov Identifier: NCT04557748.

BACKGROUND: Current evidence indicates that pelvic organ prolapse development after childbirth is strongly associated with an enlarged hiatus. However, few childbirth-related injuries beyond anal sphincter lacerations and levator ani avulsion-which explain less than a quarter of hiatal enlargement-have been investigated. Other types of injuries that lead to an enlarged hiatus and contribute to prolapse development remain incompletely explored. The perineal complex components (perineal membrane, perineal body, and levator ani) are responsible for hiatal closure and form a distinct anatomical and functional unit. Yet how and whether this complex is injured during childbirth and how such injuries can be identified through imaging has not been well characterized in the literature. OBJECTIVE: We sought to evaluate the perineal complex components using 3-dimensional endovaginal ultrasound at 6 months postpartum and how potential defect patterns are influenced by mode of delivery. Additionally, we explored how potential defect patterns are associated with clinical and obstetric data. STUDY DESIGN: This was a secondary analysis of data from a prospective longitudinal study of postpartum women at high risk for pelvic floor injury. We used 6-month 3-dimensional endovaginal ultrasound images and data to evaluate the 3 perineal complex components and developed and applied a scoring system to assess for potential imaging abnormalities. RESULTS: Atotal of 126 women were included in the present study. In women with no visible anatomic abnormality, there was a convergence of tissue to the midline at the perineal body level that was not present in other scans. This configuration was divided into 2 features: an hourglass appearance and a visible transverse band, which together we termed the Hourglass-Band pattern. In women with a vaginal delivery (n=94), the 2 features were 2.4 and 4.1 times more likely to be absent, respectively. The Hourglass-Band pattern was altered in 45% of vaginal deliveries, indicating level III imaging abnormalities in nearly half the cohort and highlighting the prevalence of childbirth-related changes among high-risk women. In the cesarean delivery control group (n=32), an altered Hourglass-Band pattern was seen in 16% of subjects, suggesting the possibility of anatomical variation or differences in sonographic tissue characteristics. CONCLUSION: The altered Hourglass-Band pattern is an imaging abnormality that is strongly associated with difficult vaginal birth, distinct from levator ani avulsion and anal sphincter laceration, and potentially repairable. If confirmed as a childbirth-related injury, studying Hourglass-Band alterations could enhance our understanding of alternative injury mechanisms and inform pelvic floor injury prevention and recovery strategies postpartum.

Although it is difficult to achieve expertise in surgical anatomy of the female perineum, this is essential for patient counseling, clinical decision making, and surgical safety. Education of female pelvic anatomy has often relied on historical illustrations that contain inaccuracies and omissions. Therefore, the Society of Gynecologic Surgeons Pelvic Anatomy Group was established to promote accuracy through standardization of terminology, to explore anatomy through three-dimensional magnetic resonance imaging (MRI) technology, and to disseminate knowledge through the development of a website that uses the human body as a primary source of education. This review by members of the Pelvic Anatomy Group highlights a part of this work by using clinical photos, cadaver dissections, and MRIs to discuss an anatomic approach to common surgical scenarios involving the vulva and perineum.