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Updated: May 21, 2025
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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
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Morphometric Characterization of Levator Ani Subdivisions in Healthy Controls and Patients: An MRI Study Using 3D
Nina Jessica Gmür1, Soleen Ghafoor2, Klaus Steigmiller3
1Department of Gynecology, University Hospital Zurich, University of Zurich, Zurich, Switzerland. nina.gmuer@uzh.ch.
International Urogynecology Journal
|March 20, 2025
Summary
New MRI techniques provide quantitative 3D morphometry of the levator ani muscle (LAM) in women with pelvic organ prolapse (POP). Patients showed lower muscle insertions and longer muscle lengths compared to controls, offering potential for improved POP diagnostics.
Area of Science:
- Pelvic floor anatomy and imaging
- Biomechanical analysis of pelvic organ prolapse (POP)
Background:
- Levator ani muscle (LAM) morphometry has traditionally been assessed descriptively or semi-quantitatively.
- Advanced MRI techniques, such as the 3D pelvic inclination correction system (3D PICS), enable detailed, quantitative 3D visualization of pelvic floor structures.
- Understanding LAM morphology is crucial for diagnosing and managing pelvic organ prolapse (POP).
Purpose of the Study:
- To quantitatively assess morphometric characteristics of LAM subdivisions using 3D PICS MRI.
- To compare LAM morphology between premenopausal nulliparous asymptomatic women (controls) and symptomatic patients with POP (Pelvic Organ Prolapse Quantification [POP-Q] ≥ II).
Main Methods:
- Controlled MRI study analyzing scans from 44 premenopausal women (22 controls, 22 POP patients).
- Application of the 3D PICS coordinate system for precise 3D-Cartesian coordinate analysis of LAM origins and insertions.
- Calculation of interrater reliability (IRR) and description of muscle distances, angles, and lengths.
Main Results:
- No significant differences in LAM origins were observed between groups.
- Symptomatic patients exhibited significantly lower insertions of vertically oriented muscles (pubovaginal, puboperineal, puboanal) along the superior-inferior axis (6.1-8.2 mm lower).
- Horizontally oriented puborectal muscle insertions showed a smaller difference (1.8 mm), while muscle lengths were 4-24% longer in patients.
Conclusions:
- This study provides the first in vivo geometric 3D data on LAM morphology in 3D PICS for both controls and POP patients.
- Quantitative 3D coordinates, lengths, and angles of LAM subdivisions can serve as a foundation for future imaging-based diagnostics of POP.
- Observed differences in muscle insertions and lengths may contribute to the pathophysiology of pelvic organ prolapse.
Keywords:
3D pelvic inclination correction system (3D PICS)InsertionMRIMorphometryPelvic floor musclesPelvic organ prolapse
