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A Geometric Capacity-Demand Analysis of Maternal Levator Muscle Stretch Required for Vaginal Delivery.

ABSTRACT: Because levator ani (LA) muscle injuries occur in approximately 13% of all vaginal births, insights are needed to better prevent them. In Part I of this paper, we conducted an analysis of the bony and soft tissue factors contributing to the geometric "capacity" of the maternal pelvis and pelvic floor to deliver a fetal head without incurring stretch injury of the maternal soft tissue. In Part II, we quantified the range in demand, represented by the variation in fetal head size and shape, placed on the maternal pelvic floor. In Part III, we analyzed the capacity-to-demand geometric ratio, g, in order to determine whether a mother can deliver a head of given size without stretch injury. The results of a Part I sensitivity analysis showed that initial soft tissue loop length (SL) had the greatest effect on maternal capacity, followed by the length of the soft tissue loop above the inferior pubic rami at ultimate crowning, then subpubic arch angle (SPAA) and head size, and finally the levator origin separation distance. We found the more caudal origin of the puborectal portion of the levator muscle helps to protect it from the stretch injuries commonly observed in the pubovisceral portion. Part II fetal head molding index (MI) and fetal head size revealed fetal head circumference values ranging from 253 to 351?mm, which would increase up to 11?mm upon face presentation. The Part III capacity-demand analysis of g revealed that, based on geometry alone, the 10th percentile maternal capacity predicted injury for all head sizes, the 25th percentile maternal capacity could deliver half of all head sizes, while the 50th percentile maternal capacity could deliver a head of any size without injury. If ultrasound imaging could be operationalized to make measurements of ratio g, it might be used to usefully inform women on their level of risk for levator injury during vaginal birth.

SUBMITTER: Tracy PV

PROVIDER: S-EPMC4843853 | biostudies-other | 2016 Feb

REPOSITORIES: biostudies-other

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A Geometric Capacity-Demand Analysis of Maternal Levator Muscle Stretch Required for Vaginal Delivery.

Tracy Paige V PV DeLancey John O JO Ashton-Miller James A JA

Journal of biomechanical engineering 20160201 2

Because levator ani (LA) muscle injuries occur in approximately 13% of all vaginal births, insights are needed to better prevent them. In Part I of this paper, we conducted an analysis of the bony and soft tissue factors contributing to the geometric "capacity" of the maternal pelvis and pelvic floor to deliver a fetal head without incurring stretch injury of the maternal soft tissue. In Part II, we quantified the range in demand, represented by the variation in fetal head size and shape, placed ...[more]

PMID: 26746116

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Project description:ImportanceAddressing severe maternal morbidity (SMM) is a public health priority in the US. Use of labor neuraxial analgesia for vaginal delivery is suggested to reduce the risk of postpartum hemorrhage (PPH), the leading cause of preventable severe maternal morbidity.ObjectiveTo assess the association between the use of labor neuraxial analgesia for vaginal delivery and SMM.Design, setting, and participantsIn this population-based cross-sectional study, women aged 15 to 49 years undergoing their first vaginal delivery were included. Data were taken from hospital discharge records from New York between January 2010 and December 2017. Data were analyzed from November 2020 to November 2021.ExposuresNeuraxial analgesia (ie, epidural or combined spinal-epidural) vs no neuraxial analgesia.Main outcomes and measuresThe primary outcome was SMM, as defined by the US Centers for Disease Control and Prevention, and the secondary outcome was PPH. Adjusted odds ratios (aORs) and 95% CIs of SMM associated with neuraxial analgesia were estimated using the inverse propensity score-weighting method and stratified according to race and ethnicity (non-Hispanic White vs racial and ethnic minority women, including non-Hispanic Asian or Pacific Islander, non-Hispanic Black, Hispanic, and other race and ethnicity) and to the comorbidity index for obstetric patients (low-risk vs high-risk women). The proportion of the association of neuraxial analgesia with the risk of SMM mediated through PPH was estimated using mediation analysis.ResultsOf 575 524 included women, the mean (SD) age was 28 (6) years, and 46 065 (8.0%) were non-Hispanic Asian or Pacific Islander, 88 577 (15.4%) were non-Hispanic Black, 104 866 (18.2%) were Hispanic, 258 276 (44.9%) were non-Hispanic White, and 74 534 (13.0%) were other race and ethnicity. A total of 400 346 women (69.6%) were in the low-risk group and 175 178 (30.4%) in the high-risk group, and 272 921 women (47.4%) received neuraxial analgesia. SMM occurred in 7712 women (1.3%), of which 2748 (35.6%) had PPH. Before weighting, the incidence of SMM was 1.3% (3486 of 272 291) with neuraxial analgesia compared with 1.4% (4226 of 302 603) without neuraxial analgesia (risk difference, -0.12 per 100; 95% CI, -0.17 to -0.07). After weighting, the aOR of SMM associated with neuraxial analgesia was 0.86 (95% CI, 0.82-0.90). Decreased risk of SMM associated with neuraxial analgesia was similar between non-Hispanic White women and racial and ethnic minority women and between low-risk and high-risk women. More than one-fifth (21%; 95% CI, 14-28) of the observed association of neuraxial analgesia with the risk of SMM was mediated through the decreased risk of PPH.Conclusions and relevanceFindings from this study suggest that use of neuraxial analgesia for vaginal delivery is associated with a 14% decrease in the risk of SMM. Increasing access to and utilization of labor neuraxial analgesia may contribute to improving maternal health outcomes.

Project description:The human fungal pathogen Candida albicans is the major etiological agent of vulvovaginal candidiasis (VVC). Despite this fact, other non-albicans Candida (NAC) species have frequently been reported, as well. Despite their presence in the vaginal environment, little is known about their capacities to elicit immune responses classically associated with C. albicans-mediated immunopathology, including neutrophil recruitment and proinflammatory cytokine signaling. Therefore, using a combination of in vitro and in vivo approaches, we undertook a comparative analysis to determine whether a representative panel of NAC species could colonize, induce immunopathological markers, or cause damage at the vaginal mucosa. Using a murine model of VVC, C. albicans was found to induce robust immunopathology (neutrophils and interleukin 1β [IL-1β]) and elicit mucosal damage. However, all the NAC species tested (including C. dubliniensis, C. tropicalis, C. parapsilosis, C. krusei, C. glabrata, and C. auris) induced significantly less damage and neutrophil recruitment than C. albicans, despite achieving similar early colonization levels. These results largely correlated with a notable lack of ability by the NAC species (including C. dubliniensis and C. tropicalis) to form hyphae both in vitro and in vivo Furthermore, both C. dubliniensis and C. tropicalis induced significantly less expression of the ECE1 gene encoding candidalysin, a key fungal virulence determinant driving VVC immunopathology. In order to determine the relative capacities of these species to elicit inflammasome-dependent IL-1β release, both wild-type and NLRP3-/- THP-1 cells were challenged in vitro While most species tested elicited only modest amounts of IL-1β, challenge with C. albicans led to significantly elevated levels that were largely NLRP3 dependent. Collectively, our findings demonstrate that although NAC species are increasingly reported as causative agents of VVC, C. albicans appears to be exceedingly vaginopathogenic, exhibiting robust immunopathology, hypha formation, and candidalysin expression. Thus, this study provides mechanistic insight into why C. albicans is overwhelmingly the major pathogen reported during VVC.

Dataset Information

A Geometric Capacity-Demand Analysis of Maternal Levator Muscle Stretch Required for Vaginal Delivery.

Publications

A Geometric Capacity-Demand Analysis of Maternal Levator Muscle Stretch Required for Vaginal Delivery.

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