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Pelvic cross-sectional area at the level of the levator ani and prolapse

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Abstract

Introduction and hypothesis

Intraabdominal pressure acts on the pelvic floor through an aperture surrounded by bony and muscular structures of the pelvis. A small pilot study showed the area of the anterior portion of this plane is larger in pelvic organ prolapse. We hypothesize that there is a relationship between prolapse and anterior (APA) and posterior (PPA) pelvic cross-sectional area in a larger, more diverse population.

Study design

MRIs from 30 prolapse subjects and 66 controls were analyzed in this case-control study. The measurement plane was tilted to approximate the level of the levator ani attachments. Three evaluators made measurements. Patient demographic characteristics were compared using Wilcoxon rank-sum and Fisher’s exact tests. A multivariable logistic regression model identified factors independently associated with prolapse.

Results

Controls were 3.7 years younger and had lower parity, but groups were similar in terms of race, height, and BMI. Cases had a larger APA (p < 0.0001), interspinous diameter (ISD) (p = 0.001), anterior-posterior (AP) diameter (p = 0.01), and smaller total obturator internus muscle (OIM) area (p = 0.002). There was no difference in the size of the PPA(p = 0.12). Bivariate logistic regression showed age (p = 0.007), parity (p = 0.009), ISD (p = 0.002), AP diameter (p = 0.02), APA (p < 0.0001), and OIM size (p = 0.01) were significantly associated with prolapse; however, PPA was not (p = 0.12). After adjusting for age, parity, and major levator defect, prolapse was significantly associated with increased anterior pelvic area (p = 0.001).

Conclusions

We confirm that a larger APA and decreasing OIM area are associated with prolapse. The PPA was not significantly associated with prolapse.

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Funding

Supported by National Institutes of Health (NIH) ORWH SCOR grant P50 HD044406, the Eunice Kennedy Shriver National Institute of Child Health and Human Development R01 HD038665 and National Institute of Diabetes, Digestive, and Kidney Diseases R01 DK51405 and R21HD079908. Investigator support for C.W.S. was provided by the National Institute of Child Health and Human Development WRHR Career Development Award K12 HD065257. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

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Authors and Affiliations

  1. Female Pelvic Medicine and Reconstructive Surgery, Rush University Medical Center, Chicago, IL, USA

    Anne G. Sammarco

  2. Society for Gynecologic Surgeons Pelvic Anatomy Group- Imaging, East Dundee, IL, USA

    Anne G. Sammarco, David Sheyn, Christopher X. Hong & John O. Delancey

  3. Female Pelvic Medicine and Reconstructive Surgery, University Hospitals Cleveland Medical Center/ Metro Health Medical Center, Cleveland, OH, USA

    David Sheyn

  4. Obstetrics and Gynecology, University of Pennsylvania, Philadelphia, PA, USA

    Christopher X. Hong

  5. Female Pelvic Medicine and Reconstructive Surgery, Michigan Medicine, Ann Arbor, MI, USA

    Emily K. Kobernik, Carolyn W. Swenson & John O. Delancey

Authors
  1. Anne G. Sammarco
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  2. David Sheyn
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  3. Christopher X. Hong
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  4. Emily K. Kobernik
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  5. Carolyn W. Swenson
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  6. John O. Delancey
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Correspondence to Anne G. Sammarco.

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This paper was presented as a Poster at the 46th Annual Scientific meeting of the Society of Gynecologic Surgeons in Jacksonville, FL, July, 2020.

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Sammarco, A.G., Sheyn, D., Hong, C.X. et al. Pelvic cross-sectional area at the level of the levator ani and prolapse. Int Urogynecol J 32, 1007–1013 (2021). https://doi.org/10.1007/s00192-020-04546-4

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  • DOI: https://doi.org/10.1007/s00192-020-04546-4

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