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Updated: Jun 1, 2026

Quantification of Levator Ani Hiatus Enlargement by Magnetic Resonance Imaging in Males and Females with Pelvic Organ Prolapse
Published on: April 17, 2019
Anal sphincter complex muscles defects and dysfunction in asymptomatic parous women
Milena M Weinstein1, Dolores H Pretorius, Sung-Ae Jung
1The Pelvic Floor Function and Disorder Group, University of California, San Diego, CA, USA.
Introduction And Hypothesis:
We aimed to determine anatomy and function of anal sphincter complex using three-dimensional ultrasound (3D-US) and manometry in asymptomatic parous women.
Methods:
3D-US of puborectalis muscle (PRM), external (EAS), and internal anal sphincters (IAS) anatomy was performed in 45 women without pelvic floor dysfunction. To assess function, rest and squeeze vaginal and anal pressures were measured. Based on 3D-US, subjects were divided into injured and uninjured groups.
Results:
Forty-four of 45 subjects had adequate PRM images. The injured PRM (N = 14) group had significantly lower vaginal pressures as compared with uninjured PRM group (N = 30; p = 0.001). Four of 45 subjects with IAS and EAS defects had lower resting and squeeze anal canal pressure. Muscle injury to IAS, EAS and PRM in the same individual was uncommon.
Conclusions:
In asymptomatic parous women, PRM defects were more common than the EAS/IAS defects but defects in more than one muscle were infrequent. Subjects with injured PRM had low vaginal pressure than the ones without.
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