Persistent occiput posterior position and stress distribution in levator ani muscle during vaginal delivery computed by a finite element model

Finite element analysis of female pelvic organ prolapse mechanism: current landscape and future opportunities

The prevalence of pelvic organ prolapse (POP) has been steadily increasing over the years, rendering it a pressing global health concern that significantly impacts women's physical and mental wellbeing as well as their overall quality of life. With the advancement of three-dimensional reconstruction and computer simulation techniques for pelvic floor structures, research on POP has progressively shifted toward a biomechanical focus. Finite element (FE) analysis is an established tool to analyze the biomechanics of complex systems. With the advancement of computer technology, an increasing number of researchers are now employing FE analysis to investigate the pathogenesis of POP in women. There is a considerable number of research on the female pelvic FE analysis and to date there has been less review of this technique. In this review article, we summarized the current research status of FE analysis in various types of POP diseases and provided a detailed explanation of the issues and future development in pelvic floor disorders. Currently, the application of FE analysis in POP is still in its exploratory stage and has inherent limitations. Through continuous development and optimization of various technologies, this technique can be employed with greater accuracy to depict the true functional state of the pelvic floor, thereby enhancing the supplementation of the POP mechanism from the perspective of computer biomechanics.

The significance of positional care combined with doula delivery during childbirth in the correction of abnormal fetal position

OBJECTIVE

To explore the effects of positional care combined with doula delivery during childbirth in the correction of abnormal fetal position.

METHODS

In this retrospective study, a total 108 pregnant women with abnormal fetal orientation were included from February 2018 to February 2021 in the Jinan City People's Hospital. Among them, 54 patients who received positional care combined with doula delivery were included in the intervention group (IG), while the other 54 patients who received routine nursing were included in the control group (CG). The data of the fetal orientation correction, delivery method and the pain score of puerpera of two groups were collected. The length of delivery, delivery fear score, the degree of neonatal asphyxia and nursing satisfaction were observed as the secondary outcomes.

RESULTS

Compared with the CG, puerpera in the IG had more occipital anterior position, less occipital transverse and posterior position, higher eutocia rate, lower pain and fear scores and shorter length of delivery; the Apgar score and nursing satisfaction were higher in the IG (all P<0.05).

CONCLUSION

Positional care combined with doula delivery can effectively correct abnormal fetal orientation, improve the rate of eutocia, reduce puerpera's pain and fear, shorten the length of delivery, and improve the quality of neonatal outcome and patients' satisfaction.

Analysis of questions by patients with pelvic organ prolapse about vaginal pessaries resulting in a checklist for their physicians

OBJECTIVE

International guidelines recommend vaginal pessaries as a first-choice treatment of symptomatic pelvic organ prolapse (POP). Gynecologists rarely receive systematic training or just do not take the time to communicate with their patients. We hypothesized that we could identify key deficits and limitations of counseling before or during pessary therapy from questions directed to manufacturers with the aim to improve and promote health literacy of women with POP.

METHODS

We approached five manufacturers to provide anonymized inquiries related to pessary use. After exclusion of duplicates and questions about obstetric pessaries, 174 data sets from 145 patients remained.

RESULTS

In 19/145 patients (13.1%), a 2nd degree, and in 94/145 (64.8%), a 3rd-4th degree of POP was identified. Four patients had additional urinary incontinence. In 32/145 (22.1%), the severity of POP could not be identified. The age of patients ranged from 27 to 98 (mean = 63.7) years. Most inquiries were related to the selected pessary models or sizes (40/174; 22.9%), self-management (20/174; 11.5%), and technical aspects such as shelf life or appropriate cleaning (26/174; 14.9%). Pain or voiding dysfunction was present in 17/174 remarks (9.7%). Lifestyle questions related to the use of pessaries during sport, menstruation, or mechanical anticonception. The cube pessary was in the focus of interest followed by the sieve bowl, urethra, ring, and Gellhorn device. The list of questions was summarized as a checklist stratified according to priorities.

CONCLUSION

The checklist should help improve counseling and self-management of patients to optimize the benefit/risk ratio of conservative treatment of pelvic floor diseases.

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.

Effects of yoga on the intervention of levator ani hiatus in postpartum women: a prospective study

[Purpose] This study aimed to explore the application value of yoga intervention in early postpartum recovery of the levator ani muscle hiatus (LAH) area. [Participants and Methods] Females in natural labor from May 2020 to November 2020 in the Third People’s Hospital of Sun Yat-sen University Ultrasound Research Center were prospectively included for a pelvic ultrasound examination. The control group received no intervention. The experimental group received 60-min yoga once a week from week 1 to week 12 postpartum. A pelvic ultrasound examination was performed on the week 6 and week 12 postpartum. The LAH area was measured at rest, during contraction and Valsalva maneuver. [Results] A total of 128 participants who met the inclusion criteria were selected and randomly assigned to the control group (n=66) and the experimental group (n=62) in pre and post intervention design. No significant differences were found in age, parity, body mass index, and fetal weight between the control and experimental groups. Further, no significant difference was observed in the LAH area between the control and experimental groups at rest, during contraction and Valsalva maneuver on the week 6 postpartum. However, the LAH area in experimental group significantly reduced at rest, during contraction and Valsalva maneuver on the week 12 postpartum. The differences of LAH area (date week 6 minus date week 12) in the control group at rest, during contraction and Valsalva maneuver were 0.12 ± 3.12 cm², 0.80 ± 2.29 cm², and 0.80 ± 4.22 cm², while in the control these were 1.95 ± 3.41 cm², 1.39 ± 1.91 cm², and 3.81 ± 5.49 cm², respectively. Compared with control group, the differences of LAH area significantly increased in experimental group at rest and during Valsalva maneuver. [Conclusion] Yoga intervention can help in the recovery of LAH.

Levator ani avulsion: a Systematic evidence review (LASER)

BACKGROUND

There is variation in the reported incidence rates of levator avulsion (LA) and paucity of research into its risk factors.

OBJECTIVE

To explore the incidence rate of LA by mode of birth, imaging modality, timing of diagnosis and laterality of avulsion.

SEARCH STRATEGY

We searched MEDLINE, EMBASE, CINAHL, AMED and MIDIRS with no language restriction from inception to April 2019.

STUDY ELIGIBILITY CRITERIA

A study was included if LA was assessed by an imaging modality after the first vaginal birth or caesarean section. Case series and reports were not included.

DATA COLLECTION AND ANALYSIS

RevMan v5.3 was used for the meta-analyses and SW SAS and STATISTICA packages were used for type and timing of imaging analyses.

RESULTS

We included 37 primary non-randomised studies from 17 countries and involving 5594 women. Incidence rates of LA were 1, 15, 21, 38.5 and 52% following caesarean, spontaneous, vacuum, spatula and forceps births, respectively, with no differences by imaging modality. Odds ratio of LA following spontaneous birth versus caesarean section was 10.69. The odds ratios for LA following vacuum and forceps compared with spontaneous birth were 1.66 and 6.32, respectively. LA was more likely to occur unilaterally than bilaterally following spontaneous (P < 0.0001) and vacuum-assisted (P = 0.0103) births but not forceps. Incidence was higher if assessment was performed in the first 4 weeks postpartum.

CONCLUSIONS

LA incidence rates following caesarean, spontaneous, vacuum and forceps deliveries were 1, 15, 21 and 52%, respectively. Ultrasound and magnetic resonance imaging were comparable tools for LA diagnosis.

TWEETABLE ABSTRACT

Levator avulsion incidence rates after caesarean, spontaneous, vacuum and forceps deliveries were 1, 15, 21 and 52%, respectively.

Finite element modeling of maximum stress in pelvic floor structures during the head expulsion (FINESSE) study

INTRODUCTION AND HYPOTHESIS

Several studies have assessed birth-related deformations of the levator ani muscle (LAM) and perineum on models that depicted these elements in isolation. The main aim of this study was to develop a complex female pelvic floor computational model using the finite element method to evaluate points and timing of maximum stress at the LAM and perineum in relation to the birth process.

METHODS

A three-dimensional computational model of the female pelvic floor was created and used to simulate vaginal birth based on data from previously described real-life MRI scans. We developed three models: model A (LAM without perineum); model B (perineum without LAM); model C (a combined model with both structures).

RESULTS

The maximum stress in the LAM was achieved when the vertex was 9 cm below the ischial spines and measured 37.3 MPa in model A and 88.7 MPa in model C. The maximum stress in the perineum occurred at the time of distension by the suboocipito-frontal diameter and reached 86.7 MPa and 119.6 MPa in models B and C, respectively, while the stress in the posterior fourchette caused by the suboccipito-bregmatic diameter measured 36.9 MPa for model B and 39.8 MPa for model C.

CONCLUSIONS

Including perineal structures in a computational birth model simulation affects the level of stress at the LAM. The maximum stress at the LAM and perineum seems to occur when the head is lower than previously anticipated.

Feasibility and safety of antepartum tactile imaging

Introduction and hypothesis

Quantitative characterization of the birth canal and critical structures before delivery may provide risk assessment for maternal birth injury. The objective of this study was to explore imaging capability of an antepartum tactile imaging (ATI) probe.

Methods

Twenty randomly selected women older than 21 years with completed 35th week of pregnancy and a premise of vaginal delivery were enrolled in the feasibility study. The biomechanical data were acquired using the ATI probe with a double-curved surface, shaped according to the fetal skull and equipped with 168 tactile sensors and an electromagnetic motion tracking sensor. Software package COMSOL Multiphysics was used for finite element modeling. Subjects were asked for assessment of pain and comfort levels experienced during the ATI examination.

Results

All 20 nulliparous women were successfully examined with the ATI. Mean age was 27.8 ± 4.1 years, BMI 30.7 ± 5.8, and week of pregnancy 38.8 ± 1.4. Biomechanical mapping with the ATI allowed real-time observation of the probe location, applied load to the vaginal walls, and a 3D tactile image composition. The nonlinear finite element model describing the stress–strain relationship of the pelvic tissue was developed and used for calculation of Young’s modulus (E). Average perineal elastic modulus was 11.1 ± 4.3 kPa, levator ani 4.8 ± 2.4 kPa, and symphysis–perineum distance was 30.1 ± 6.9 mm. The pain assessment level for the ATI examination was 2.1 ± 0.8 (scale 1–4); the comfort level was 2.05 ± 0.69 (scale 1–3).

Conclusions

The antepartum examination with the ATI probe allowed measurement of the tissue elasticity and anatomical distances. The pain level was low and the comfort level was comparable with manual palpation.