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Quantification of Levator Ani Hiatus Enlargement by Magnetic Resonance Imaging in Males and Females with Pelvic Organ Prolapse
Published on: April 17, 2019
Injury-associated levator ani muscle and anal sphincter ooedema following vaginal birth: a secondary analysis of the
F Pipitone1, J M Miller2, Jol DeLancey1,3
1Pelvic Floor Research Group, Michigan Medicine, University of Michigan, 1540 E Hospital Dr, Ann Arbor, MI, 48109, USA.
Insights
The pubovisceral muscle is most frequently injured after vaginal birth, showing significantly higher edema than other levator ani components. This highlights unequal injury patterns in pelvic floor muscles following childbirth.
Area of Science:
- Pelvic floor biomechanics
- Obstetric trauma research
- Medical imaging in women's health
Background:
- Childbirth can cause pelvic floor muscle injury, impacting women's health.
- The levator ani muscle complex and external anal sphincter are crucial for pelvic support.
- Understanding injury patterns is vital for developing effective treatments and prevention strategies.
Purpose of the Study:
- To investigate if all levator ani muscle components (pubovisceral, puborectal, iliococcygeal) and the external anal sphincter are equally affected by edema post-vaginal birth.
- To identify which specific pelvic floor muscles are most vulnerable to injury.
Main Methods:
- An observational, cross-sectional study was conducted.
- MRI scans were used to assess muscle edema in 78 primiparous women 6-8 weeks postpartum.
- Edema was quantified in each levator ani component and the external anal sphincter.
Main Results:
- 51.3% of women showed edema in the pubovisceral muscle, compared to 5.1% in the puborectal and 5.1% in the iliococcygeal muscles.
- No edema was observed in the external anal sphincter, even in cases of sphincter laceration.
- Pubovisceral muscle edema occurred seven times more frequently than in other analyzed muscles (P < 0.001).
Conclusions:
- The pubovisceral muscle is disproportionately affected by injury after vaginal birth, indicating unequal vulnerability among levator ani components.
- The external anal sphincter may have a different injury mechanism, as it showed no edema.
- Mapping these injury patterns on MRI aids in understanding mechanisms and guiding future research for treatment and prevention.
Objective:
To determine whether all three components of the levator ani muscle (pubovisceral [= pubococcygeal], puborectal and iliococcygeal) and the external anal sphincter are equally affected by oedema associated with muscle injury after vaginal birth.
Design:
Observational cross-sectional study.
Setting:
Michigan Medicine, University of Michigan.
Population:
Primiparous women classified as high risk for levator ani muscle injury during childbirth.
Method:
MRI scans obtained 6-8 weeks postpartum were analysed. Muscle oedema was assessed on axial and coronal fluid-sensitive magnetic resonance (MRI) scans. Presence of oedema was separately determined in each levator ani muscle component and in the external anal sphincter for all subjects. Descriptive statistics and correlation with obstetric variables were obtained.
Main Outcome Measures:
Oedema score on fluid-sensitive MRI scans.
Results:
Of the 78 women included in this cohort, 51.3% (n = 40/78) showed muscle oedema in the pubovisceral (one bilateral avulsion excluded), 5.1% (n = 4/78) in the puborectal and 5.1% (n = 4/78) in the iliococcygeal muscle. No subject showed definite oedema on external anal sphincter. Incidence of oedema on the pubovisceral muscle was seven times higher than on any of the other analysed muscles (all paired comparisons, P < 0.001).
Conclusions:
Even in the absence of muscle tearing, the pubovisceral muscle shows by far the highest incidence of injury, establishing that levator components are not equally affected by childbirth. External anal sphincter did not show oedema-even in women with sphincter laceration- suggesting a different injury mechanism. Developing a databased map of injured areas helps understand injury mechanisms that can guide us in honing research on treatment and prevention.
Tweetable Abstract:
Injury-associated levator ani muscle and anal sphincter oedema mapping on MRI reveals vulnerable muscle components after childbirth.
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