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Updated: Jun 8, 2026

Quantification of Levator Ani Hiatus Enlargement by Magnetic Resonance Imaging in Males and Females with Pelvic Organ Prolapse
Published on: April 17, 2019
Levator defects affect perineal position independently of prolapse status
Natalie A Clark1, Cynthia A Brincat, Aisha A Yousuf
1Pelvic Floor Research Group, University of Michigan, Ann Arbor, MI, USA. naclark@med.umich.edu
Objective:
The purpose of this study was to determine the effect of levator defects on perineal position and movement irrespective of prolapse status.
Study Design:
Forty women from an ongoing study were divided into 2 groups of 20 women with and without severe levator defects. Prolapse status was matched between groups, with 50% of the women having stage III or greater anterior wall prolapse. Perineal structure locations were measured against standard axes on magnetic resonance scans at rest, maximum contraction (Kegel), and maximum Valsalva maneuver. Differences in location were calculated and compared.
Results:
In women with levator defects, independently of prolapse status: (1) At rest, the perineal body was 1.3 cm, and the anal sphincter was 1.0 cm more caudal (P ≤ .01); at maximum contraction, the perineal body and the anal sphincter were both 1.2 cm more caudal (P ≤ .01); with maximum Valsalva maneuver, the perineal body was 1.3 cm more caudal, and the anal sphincter was 1.2 cm more caudal (P ≤ .01). (2) At rest, the levator hiatus was 0.8 cm larger, and the urogenital hiatus was 1.0 cm larger (P ≤ .01). (3) At rest, the bladder was 0.07 cm more posterior (P ≤ .02); with maximum contraction, it was 1.9 cm lower (P ≤ .02). (4) With maximum Valsalva maneuver, the bladder was 1.5 cm lower and displaced further caudally (P ≤ .03).
Conclusion:
When we controlled for prolapse, the women with levator defects had a more caudal location of their perineal structures and larger hiatuses at rest, maximum contraction, and maximum Valsalva maneuver.
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