Characterizing the Biomechanical Properties of the Pubovisceralis Muscle Using a Genetic Algorithm and the Finite Element Method.

To better understand the disorders in the pelvic cavity associated with the pelvic floor muscles (PFM) using computational models, it is fundamental to identify the biomechanical properties of these muscles. For this purpose, we implemented an optimization scheme, involving a genetic algorithm (GA) and an inverse finite element analysis (FEA), in order to estimate the material properties of the pubovisceralis muscle (PVM). The datasets of five women were included in this noninvasive analysis. The numerical models of the PVM were built from static axial magnetic resonance (MR) images, and the hyperplastic Mooney-Rivlin constitutive model was used. The material parameters obtained were compared with the ones established through a similar optimization scheme, using Powell's algorithm. To validate the values of the material parameters that characterize the passive behavior of the PVM, the displacements obtained via the numerical models with both methods were compared with dynamic MR images acquired during Valsalva maneuver. The material parameters (c1 and c2) were higher for the GA than for Powell's algorithm, but when comparing the magnitude of the displacements in millimeter of the PVM, there was only a 5% difference, and 4% for the principal logarithmic strain. The GA allowed estimating the in vivo biomechanical properties of the PVM of different subjects, requiring a lower number of simulations when compared to Powell's algorithm.

On the Stiffness of the Mesh and Urethral Mobility: A Finite Element Analysis.

Midurethral slings are used to correct urethral hypermobility in female stress urinary incontinence (SUI), defined as the complaint of involuntary urine leakage when the intra-abdominal pressure (IAP) is increased. Structural and thermal features influence their mechanical properties, which may explain postoperative complications, e.g., erosion and urethral obstruction. We studied the effect of the mesh stiffness on urethral mobility at Valsalva maneuver, under impairment of the supporting structures (levator ani and/or ligaments), by using a numerical model. For that purpose, we modeled a sling with "lower" versus "higher" stiffness and evaluated the mobility of the bladder and urethra, that of the urethrovesical junction (the α-angle), and the force exerted at the fixation of the sling. The effect of impaired levator ani or pubourethral ligaments (PUL) alone on the organs displacement and α-angle opening was similar, showing their important role together on urethral stabilization. When the levator ani and all the ligaments were simulated as impaired, the descent of the bladder and urethra went up to 25.02 mm, that of the bladder neck was 14.57 mm, and the α-angle was 129.7 deg, in the range of what was found in women with SUI. Both meshes allowed returning to normal positioning, although at the cost of higher force exerted by the mesh with higher stiffness (3.4 N against 2.3 N), which can relate to tissue erosion. This finite element analysis allowed mimicking the biomechanical response of the pelvic structures in response to changing a material property of the midurethral synthetic mesh.

Prolapse and continence surgery in countries of the Organization for Economic Cooperation and Development in 2012.

OBJECTIVE: The purpose of this study was to report the rates and types of pelvic organ prolapse (POP) and female continence surgery performed in member countries of the Organization for Economic Co-operation and Development (OECD) in 2012. STUDY DESIGN: The published health outcome data sources of the 34 OECD countries were contacted for data on POP and female continence interventions from 2010-2012. In nonresponding countries, data were sought from national or insurer databases. Extracted data were entered into an age-specific International Classification of Disease, edition 10 (ICD-10)-compliant Excel spreadsheet by 2 authors independently in English-speaking countries and a single author in non-English-speaking countries. Data were collated centrally and discrepancies were resolved by mutual agreement. RESULTS: We report on 684,250 POP and 410,352 continence procedures that were performed in 15 OECD countries in 2012. POP procedures (median rate, 1.38/1000 women; range, 0.51-2.55 prolapse procedures/1000 women) were performed 1.8 times more frequently than continence procedures (median rate, 0.75/1000 women; range, 0.46-1.65 continence procedures/1000 women). Repairs of the anterior vaginal compartment represented 54% of POP procedures; posterior repairs represented 43% of the procedures, and apical compartment repairs represented 20% of POP procedures. Median rate of graft usage was 15.7% of anterior vaginal repairs (range, 3.3-25.6%) and 8.5% (range, 3.2-17%) of posterior vaginal repairs. Apical compartment repairs were repaired vaginally at a median rate of 70% (range, 35-95%). Sacral colpopexy represented a median rate of 17% (range, 5-65%) of apical repairs; 61% of sacral colpopexies were performed minimally invasively. Between 2010 and 2012, there was a 3.7% median reduction in transvaginal grafts, a 4.0% reduction in midurethral slings, and a 25% increase in sacral colpopexies that were performed per 1000 women. Midurethral slings represented 82% of female continence surgeries. CONCLUSION: The 5-fold variation in the rate of prolapse interventions within OECD countries needs further evaluation. The significant heterogeneity (>10 times) in the rates at which individual POP procedures are performed indicates a lack of uniformity in the delivery of care to women with POP and demands the development of uniform guidelines for the surgical management of prolapse. In contrast, the midurethral slings were the standard female continence surgery performed throughout OECD countries in 2012.

Adaptation and validation of the King's Health Questionnaire in Portuguese women with urinary incontinence.

INTRODUCTION AND HYPOTHESIS: Urinary incontinence (UI) in women is a problem of public health with psychological repercussions in various contexts of life. The aim of this study was to adapt and validate the King's Health Questionnaire (KHQ) in women with UI to Portugal. METHODS: For the adaptation, a multistep forward-back translation protocol was used. The Positive and Negative Affect Schedule and the Satisfaction with Life Scale were used to validate the KHQ. The evaluation of the psychometric properties involved the assessment of validity, reliability, and test-retest stability in 103 women. A factor analysis was conducted to explore the underlying factor structure of KHQ. Inter-domain correlation was calculated for convergent and discriminant validity assessment. RESULTS: Exploratory factor analysis identified three factors "personal limitations and daily life", "emotions and social relationships" and "urinary symptoms". Indicators of test-retest stability showed almost perfect agreement with a mean intraclass correlation coefficient (ICC) of 0.937. Internal consistency was found to be high (Cronbach's alfa > 0.7). Furthermore, the Portuguese version of the KHQ significantly correlates with the Positive and Negative Affect Schedule, supporting construct validity. CONCLUSIONS: The Portuguese version of the KHQ was found to be a valid and reliable measure of the quality of life in women with UI in Portugal, being relevant to both clinical practice and research.

Pelvic organ prolapse surgical management in Portugal and FDA safety communication have an impact on vaginal mesh.

INTRODUCTION AND HYPOTHESIS: Pelvic organ prolapse (POP) surgery has lately gained importance in gynecological practice. This study aims to characterize the evolution of POP surgical procedures conducted in Portugal in the last decade and the impact of an FDA 2011 safety communication on mesh POP surgeries. METHODS: Trends in the surgical management of POP were assessed using the Portuguese National Medical Registry. We considered all records of women with diagnosis of genital prolapse from 1 January 2000 to 31 December 2012. Additionally, we also conducted a survey among members of the Portuguese Society of Urogynecology to evaluate current practices in the surgical management of POP. RESULTS: From 2000 to 2012, 46,819 diagnoses of genital prolapse were registered, with a 105 % increase during the study period (2,368 in 2000 to 4,941 in 2012). POP mesh surgery represented only 6 % of total prolapse diagnoses, but mesh use greatly increased up to 2011, when only a slight increase was registered. Among gynecologists who responded to the questionnaire, there was considerable variability on the procedures of choice to treat POP. Fifty-seven per cent of respondents performed vaginal mesh POP surgery, but only 27 % of those actually reported having changed their practice after the FDA 2011 safety communication. CONCLUSIONS: Surgical procedures for POP conducted in Portugal greatly increased over the last decade. The use of surgical meshes is still limited, but despite FDA safety communication it has increased over the years, with a slight increase in 2012, which illustrates the need for further analyses in the coming years.

Volume of training and the ranking level are associated with the leakage of urine in young female trampolinists.

OBJECTIVES: The aim of this study was to investigate in young nulliparous female trampolinists the hypothetical associations between the level of athletic performance and the volume of training with urine leakage. DESIGN: Cross-sectional cohort study. SETTING: Professional trampolinists. PARTICIPANTS: Twenty-two female athletes participating in a trampoline national championship were included in this study. ASSESSMENT OF RISK FACTORS: The associations for player-related performance variables were evaluated using Spearman rank correlation and Kruskal-Wallis H test verified the differences between the tertiles. MAIN OUTCOME MEASURES: Rate of urinary incontinence (UI) among young athletes and the relationship with the athletic performance. Screening was performed through a questionnaire. This included the demographic sample characterization, the assessment of training volume, and the athletes' ranking in the championship. Additionally, it included the International Consultation on Incontinence Questionnaire Short-Form (ICIQ-UI-SF) to assess the leakage. RESULTS: About 72.7% of the participants reported that they experienced urine leakage during trampoline practice and described that the episodes of leakage started after the beginning of the trampoline. Significant associations between the athletic performance and the training volume were observed with the severity of incontinence. Dividing the sample in tertiles of training volume, it was observed that the third tertile was the one with greatest impact of incontinence on their quality of life (ICIQ score). CONCLUSIONS: The results confirm a high frequency of UI in young trampolinists and reveal a clear identification of the athletes' ranking and the training volume as risk factors to develop and worsen urine loss. CLINICAL RELEVANCE: Special attention from team physicians and trainers is required for this athletes' problem that is often hidden by shame. In addition, female athletes practicing high-impact sports should be informed about the risk to develop pelvic floor muscles dysfunction and should be encouraged to seek help from health professionals to minimize or even eliminate the urine incontinence.

Corrigendum: Beliefs and strategies about urinary incontinence: a possible moderation role between symptoms and sexual function, and quality of life.

[This corrects the article DOI: 10.3389/fpsyg.2023.1252471.].

Revolutionizing Women's Health: A Comprehensive Review of Artificial Intelligence Advancements in Gynecology.

Artificial intelligence has yielded remarkably promising results in several medical fields, namely those with a strong imaging component. Gynecology relies heavily on imaging since it offers useful visual data on the female reproductive system, leading to a deeper understanding of pathophysiological concepts. The applicability of artificial intelligence technologies has not been as noticeable in gynecologic imaging as in other medical fields so far. However, due to growing interest in this area, some studies have been performed with exciting results. From urogynecology to oncology, artificial intelligence algorithms, particularly machine learning and deep learning, have shown huge potential to revolutionize the overall healthcare experience for women's reproductive health. In this review, we aim to establish the current status of AI in gynecology, the upcoming developments in this area, and discuss the challenges facing its clinical implementation, namely the technological and ethical concerns for technology development, implementation, and accountability.

Artificial Intelligence and Colposcopy: Automatic Identification of Vaginal Squamous Cell Carcinoma Precursors.

Background/Objectives: While human papillomavirus (HPV) is well known for its role in cervical cancer, it also affects vaginal cancers. Although colposcopy offers a comprehensive examination of the female genital tract, its diagnostic accuracy remains suboptimal. Integrating artificial intelligence (AI) could enhance the cost-effectiveness of colposcopy, but no AI models specifically differentiate low-grade (LSILs) and high-grade (HSILs) squamous intraepithelial lesions in the vagina. This study aims to develop and validate an AI model for the differentiation of HPV-associated dysplastic lesions in this region. Methods: A convolutional neural network (CNN) model was developed to differentiate HSILs from LSILs in vaginoscopy (during colposcopy) still images. The AI model was developed on a dataset of 57,250 frames (90% training/validation [including a 5-fold cross-validation] and 10% testing) obtained from 71 procedures. The model was evaluated based on its sensitivity, specificity, accuracy and area under the receiver operating curve (AUROC). Results: For HSIL/LSIL differentiation in the vagina, during the training/validation phase, the CNN demonstrated a mean sensitivity, specificity and accuracy of 98.7% (IC95% 96.7-100.0%), 99.1% (IC95% 98.1-100.0%), and 98.9% (IC95% 97.9-99.8%), respectively. The mean AUROC was 0.990 ± 0.004. During testing phase, the sensitivity was 99.6% and 99.7% for both specificity and accuracy. Conclusions: This is the first globally developed AI model capable of HSIL/LSIL differentiation in the vaginal region, demonstrating high and robust performance metrics. Its effective application paves the way for AI-powered colposcopic assessment across the entire female genital tract, offering a significant advancement in women's healthcare worldwide.

Biomechanical properties of vaginal tissue in women with pelvic organ prolapse.

BACKGROUND/AIMS: To compare biomechanical properties of vaginal tissues between women with and without pelvic organ prolapse (POP) and investigate factors that may influence these properties. METHODS: Forty patients submitted to POP surgery and 15 non-POP cadavers were evaluated. The tissue was excised from anterior and posterior middle third vagina. The biomechanical properties considered were stiffness (E) and maximum stress (S), and they were evaluated by means of uniaxial tension tests. RESULTS: POP patients were associated with higher values of E (13.1 ± 0.8 vs. 9.5 ± 0.7 MPa; p < 0.001) and S (5.3 ± 0.5 vs. 3.2 ± 0.9 MPa; p < 0.001) in the anterior vaginal wall compared to the posterior wall. In contrast, non-POP women presented lower values of E (6.9 ± 1.1 vs. 10.5 ± 1.0 MPa; p = 0.01) and S (2.6 ± 0.4 vs. 3.5 ± 0.4 MPa; p = 0.043) in the anterior wall. The occurrence of POP was the only independent predictor of higher values of E and S in anterior vaginal samples (p = 0.003 and p = 0.008, respectively). Women with severe anterior vaginal prolapse presented higher levels of E and S in the anterior sample compared to those with lower POP stages (p = 0.001 and p = 0.01; respectively). CONCLUSION: Women with POP present significant changes of biomechanical properties in the vagina.

Strength of round and uterosacral ligaments: a biomechanical study.

PURPOSE: To investigate the tensile biomechanical properties of round and uterosacral ligaments. METHODS: Tissue samples were obtained from 15 female cadavers without pelvic organ prolapse. Uniaxial tensile tests were performed to obtain stiffness and maximum stress of round and uterosacral ligaments. Correlations were calculated using the Pearson correlation coefficient. Statistical differences between groups were tested using Student's paired and unpaired t test. RESULTS: There was a great variability in the measurements of stiffness and maximum stress in pelvic ligaments. The round ligaments demonstrated stiffness of 9.1 ± 1.6 MPa (mean ± SEM) (ranging from 2 to 25.6 MPa) and maximum stress of 4.3 ± 0.7 MPa (ranging from 1.2 to 11.5 MPa). The stiffness of the uterosacral ligaments was 14.1 ± 1.4 MPa (ranging from 5.7 to 26.1 MPa) with maximum stress of 6.3 ± 0.8 MPa (ranging from 2.2 to 11.9 MPa). There was a strong positive correlation between stiffness and maximum stress in female pelvic ligaments (ρ = 0.851; p < 0.001). The uterosacral ligaments demonstrated higher stiffness and maximum stress compared to the round ligaments (p = 0.006 and p = 0.034; respectively). Age, body mass index and menopausal status were not associated with the biomechanical proprieties of round and uterosacral ligaments. Nulliparous women had lower uterosacral stiffness (15.5 ± 1.3 vs. 10 ± 1.8 MPa; p = 0.033) and maximum stress (8.2 ± 0.9 vs. 4.2 ± 1.1 MPa; p = 0.028) compared to parous women. CONCLUSION: The uterosacral ligaments are significantly more resistant than round ligaments. Parturition seems to enhance the stiffness and maximum stress of the ligaments.

Moment of inertia as a means to evaluate the biomechanical impact of pelvic organ prolapse.

OBJECTIVES: To present an alternative measure (moment of inertia) to describe the anatomical features of the pelvic organ prolapse. METHODS: A total of 30 women (21 diagnosed as having pelvic organ prolapse and 9 as controls) were evaluated by clinical scales and magnetic resonance imaging. Imaging biometric measures were carried out. Moment of inertia, pubovisceral muscle thickness and area, and levator hiatus anterior-to-posterior and lateral measures were compared by means of non-parametric tests, as well as their correlation with demographic features of the two sample groups. RESULTS: Moment of inertia, muscle area and levator hiatus diameters were statistically different between patients and controls. Furthermore, they were also well correlated with prolapse-associated factors, such as the number of vaginal deliveries and age, as well as Pelvic Organ Prolapse Quantification system and imaging staging of levator ani defects. CONCLUSIONS: Moment of inertia can be used as a new parameter to evaluate pelvic floor damage resulting from prolapse.

Beliefs and strategies about urinary incontinence: a possible moderation role between symptoms and sexual function, and quality of life.

Background: Urinary Incontinence (UI) has numerous repercussions in women's lives, and it is underreported/underdiagnosed. Objective: The present study aimed to understand: (1) the differences between women with and without urine loss regarding Quality of Life (QoL) and Sexual Function (SF); (2) the possible moderation role of UI-related beliefs and strategies on the relationship between UI-symptom severity and SF and QoL, in women with UI. Methods: Cross-sectional Design. Participants: Primary aim: Overall, 2,578 women aged 40-65 (Mage = 49.94, DPage = 6.76) were collected online. Secondary aim: 1,538 women who self-reported having urine loss occasionally/frequently (Mage = 50.19, DPage = 6.58). All data analyses were done with IBM SPSS Statistics and R statistical system 4.0 through RStudio. Statistical Path analysis was performed with the lavaan package to study the hypothetical association and moderating effects between the variables. Results: Primary aim: women without UI had a better SF [t(2576) = 3.13, p = 0.002; 95% C.I., 0.18 to 0.80] and QoL [t(2576) = 7.71, p < 0.001; 95% C.I., 3.14 to 5.28] than their counterparts with UI. Secondary aim: UI-related coping strategies attenuated the impact of UI-symptom severity on SF(ß = -0.07; p = 0.041); the more dysfunctional the UI-related beliefs were, the poorer QoL was (ß = -0.06; p = 0.031); the more frequent the UI-related hiding/defensive strategies were, the poorer QoL was (ß = -0.26; p < 0.001). Discussion: Limitations: online data collection, which thwarted the clarification of participants, if needed; absence of a UI medical diagnosis (only self-reported measures were used). Strengths and practical implications: (i) the crucial role of UI-related beliefs and strategies in the QoL of women with UI; (ii) the impact that UI-concealing/defensive strategies have in attenuating the impact of UI-symptom severity on SF, which might be perceived as a short-term benefit and hence contribute to maintaining the UI condition and constitute a barrier to help-seeking, (iii) impact of UI-symptom severity on QoL and SF (including a comparison group entailing women without UI, which is scarcely used); and (iv) the use of gold-standard and psychometrically robust instruments. Conclusion: Changing dysfunctional UI-related beliefs and strategies in clinical settings may improve the QoL; UI-concealing strategies may reinforce themselves by immediate effects on SF, but are not functional in the long term.

Pelvic floor muscle training to improve urinary incontinence in young, nulliparous sport students: a pilot study.

INTRODUCTION AND HYPOTHESIS: Urinary incontinence (UI) is prevalent in sport students. We hypothesized that pelvic floor muscle training (PFMT) can improve pelvic floor muscle (PFM) strength and symptoms of UI in this group of physically active women. METHODS: Sixteen sport students with UI participated in this pre-post test pilot study. However, only seven of them, mean age 20.0 ± 0.8 years, completed the 8-week program. Activity level was measured by the International Physical Activity Questionnaire-Short Form (IPAQ-SF). The outcome measure was the International Consultation on Incontinence Questionnaire-Short Form (ICIQ UI SF). PFM strength was measured by manometry as maximum voluntary contraction (MVC). RESULTS: Vaginal resting pressure improved by 17.4 cmH(2)O (SD 6.7), p = 0.04 and MVC by 16.4 cmH(2)O (SD 5.8), p = 0.04. ICIQ UI SF score, frequency, and amount of leakage showed statistically significant improvement. CONCLUSIONS: PFMT increased PFM strength and reduced frequency and amount of UI episodes in sport students that completed an 8-week PFMT program. Randomized controlled trials are warranted to confirm these results.

A biomechanical study of the birth position: a natural struggle between mother and fetus.

Birth trauma affects millions of women and infants worldwide. Levator ani muscle avulsions can be responsible for long-term morbidity, associated with 13-36% of women who deliver vaginally. Pelvic floor injuries are enhanced by fetal malposition, namely persistent occipito-posterior (OP) position, estimated to affect 1.8-12.9% of pregnancies. Neonates delivered in persistent OP position are associated with an increased risk for adverse outcomes. The main goal of this work was to evaluate the impact of distinct fetal positions on both mother and fetus. Therefore, a finite element model of the fetal head and maternal structures was used to perform childbirth simulations with the fetus in the occipito-anterior (OA) and OP position of the vertex presentation, considering a flexible-sacrum maternal position. Results demonstrated that the pelvic floor muscles' stretch was similar in both cases. The maximum principal stresses were higher for the OP position, and the coccyx rotation reached maximums of 2.17[Formula: see text] and 0.98[Formula: see text] for the OP and OA positions, respectively. Concerning the fetal head, results showed noteworthy differences in the variation of diameters between the two positions. The molding index is higher for the OA position, with a maximum of 1.87. The main conclusions indicate that an OP position can be more harmful to the pelvic floor and pelvic bones from a biomechanical point of view. On the other side, an OP position can be favorable to the fetus since fewer deformations were verified. This study demonstrates the importance of biomechanical analyses to further understand the mechanics of labor.

Uniaxial mechanical behavior of the human female bladder.

INTRODUCTION AND HYPOTHESIS: The objective of the present study was to investigate the tensile biomechanical properties of the human female bladder. METHODS: Tissue samples were obtained from 13 cadavers without pelvic floor dysfunctions. We performed uniaxial tensile tests to measure the stiffness and maximum stress of the bladder tissue. Correlations were calculated using the Pearson correlation coefficient. RESULTS: The bladder tissue stiffness ranged from 1 to 4.1 MPa (mean stiffness, 1.9 ± 0.2 MPa) and the maximum stress ranged from 0.5 to 2.6 MPa (mean maximum stress, 0.9 ± 0.1 MPa). There was a strong positive correlation between stiffness and maximum stress in the bladder tissue (ρ = 0.829, p < 0.001). Tissue from women younger than 50 years presented higher bladder stiffness than did tissue from older subjects (2.1 ± 0.2 versus 1.3 ± 0.1 MPa, p = 0.02). Maximum bladder stress, however, was not associated with age (1.0 ± 0.2 versus 0.7 ± 0.1 MPa, p = 0.349). In addition, body mass index and menopausal status were not associated with these biomechanical properties. CONCLUSIONS: Age may influence the uniaxial mechanical behavior of the human female bladder.

Vaginal tissue properties versus increased intra-abdominal pressure: a preliminary biomechanical study.

BACKGROUND/AIMS: This study aims to evaluate the pelvic floor (PF) tension response during simulated increased intra-abdominal pressure (IAP) and the vaginal biomechanical properties. METHODS: A 3-dimensional computational finite element model for PF was developed based on magnetic resonance imaging from a nulliparous healthy volunteer. The model was used to simulate an IAP of 90 cm H(2)O and to evaluate the PF stresses in the longitudinal and transversal axes. The vaginal samples were obtained from 15 non-prolapsed female cadavers. A uniaxial tensile test to obtain stiffness and maximum stress of vaginal tissue in the longitudinal and transversal axes was performed. RESULTS: The simulated IAP was associated with a similar PF stress state in the longitudinal and transversal axes. The stiffness and maximum stress in vaginal tissues presented a great variability between subjects. There was no difference in the vaginal tissue elasticity (6.2 ± 1.5 vs. 5.4 ± 1.1 MPa; p = 0.592) and maximum stress (2.3 ± 0.5 vs. 2.6 ± 0.9 MPa; p = 0.692) regarding the measurements in the longitudinal and transversal axes. CONCLUSION: The isotropic biomechanical behavior of vagina is in agreement with the PF stress state response during increased IAP.

Effect of the birthing position on its evolution from a biomechanical point of view.

BACKGROUND AND OBJECTIVE: During vaginal delivery, several positions can be adopted by the mother to be more comfortable and to help the labor process. The positions chosen are very influenced by factors such as monitoring and intervention during the second stage of labor. However, there is limited evidence to support the most ideal birthing position. This work aims at contributing to a better knowledge associated with the widening of the pubic symphysis and the biomechanics of flexible and non-flexible sacrum positions that can be adopted during the second stage of labor, as well as their resulting pathophysiological consequences. METHODS: A validated computational model composed by the pelvic floor muscles attached to the bones, and a fetus head was used to simulate vaginal deliveries. This model was modified to mimic two birthing positions: one that allows the free movement of the coccyx as in flexible sacrum positions and other in which this movement is more restricted as in non-flexible sacrum positions. The widening of the pubic symphysis was also considered to facilitate the passage of the fetus head. RESULTS: The results obtained showed that, in non-flexible sacrum positions, where the coccyx movement is restricted, occur a rotation of 3.6° of the coccyx and a widening of 6 mm of the pubic symphysis. In contrast, in flexible sacrum positions, where the coccyx is free to move, occur a rotation of 15.7° of the coccyx and a widening of the pubic symphysis of 3 mm, appearing to be more beneficial for the mother's pelvis, but slightly higher stresses were detected in the pelvic floor muscles. CONCLUSIONS: Globally, the results obtained allow to conclude that different birthing positions lead to changes in the female pelvic space, so certain positions can be adopted by the mother during the second stage of labor to reduce the risk of obstructed labor and the development of several dysfunctions. More specifically, flexible sacrum positions, such as kneeling, standing, squatting and sitting positions, are more beneficial for the bone structure of her pelvis as they allow a higher coccyx movement and lower widening of the pubic symphysis.

A numerical study on fetal head molding during labor.

During vaginal delivery, the fetal head molds into an elongated shape to adapt to the birth canal, a process known as fetal head molding. However, excessive molding can occur due to prolonged labor or strong contractions, leading to several disorders on the fetal head. This work aims to perform a numerical study on the biomechanics of fetal head molding by measuring specific diameters and the corresponding molding index. A finite element model of the pelvic floor muscles and the fetal body was used. The fetal head is composed of the skin and soft tissues, the skull with sutures and fontanelles, and the brain. The sutures and fontanelles were modeled with membrane elements and characterized by a visco-hyperelastic constitutive model adapted to a plane stress state. Simulations were performed to replicate the second stage of labor in the vertex presentation and occipito-anterior position. With the introduction of viscoelasticity to assess a time-dependent response, a prolonged second stage of labor resulted in higher molding. The pressure exerted by the birth canal and surrounding structures, along with the presence of the pelvic floor muscles, led to a percentage of molding of 9.1%. Regarding the pelvic floor muscles, a 19.4% reduction on the reaction forces and a decrease of 2.58% in muscle stretching was reported, which indicates that sufficient molding may lead to fewer injuries. The present study demonstrates the importance of focusing on the fetus injuries with non-invasive methods that can allow to anticipate complications during labor.

Computational modeling approach to study the effects of fetal head flexion during vaginal delivery.

OBJECTIVE: The purpose of this study was to investigate the influence of fetal head flexion during vaginal delivery with a 3-dimensional computational finite element model. STUDY DESIGN: A finite element model of the pelvic skeletal structure, pelvic floor, and fetus was developed. The movements of the fetus during birth were simulated in engagement, descent, flexion, internal rotation, and extension of the fetal head. The opposite forces against the fetal descendent and the stress of the pelvic floor muscles were obtained on simulations with different degrees of head flexion. RESULTS: The simulated increase in fetal head flexion is associated with lower values of opposite forces against the fetal descent. The descending fetus with abnormal head flexion also meets resistance in later stations. Lower stress on the pelvic floor was demonstrated with simulated increase in fetal head flexion during vaginal delivery. CONCLUSION: This analytic evidence suggests that the fetal head flexion during vaginal delivery may facilitate birth and protect the pelvic floor.