Obstetrics & Gynecology

Skip Navigation LinksHome > October 2006 - Volume 108 - Issue 4 > Quantification of Levator Ani Cross-Sectional Area Differenc...
Obstetrics & Gynecology:
doi: 10.1097/01.AOG.0000233153.75175.34
Original Research

Quantification of Levator Ani Cross-Sectional Area Differences Between Women With and Those Without Prolapse

Hsu, Yvonne MD; Chen, Luyun MS; Huebner, Markus MD; Ashton-Miller, James A. PhD; DeLancey, John O.L. MD

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OBJECTIVE: Compare levator ani cross-sectional area as a function of prolapse and muscle defect status.

METHODS: Thirty women with prolapse and 30 women with normal pelvic support were selected from an ongoing case-control study of prolapse. For each of the two groups, 10 women were selected from three categories of levator defect severity: none, minor, and major identified on supine magnetic resonance scans. Using those scans, three-dimensional (3D) models of the levator ani muscles were made using a modeling program (3D Slicer), and cross-sections of the pubic portion were calculated perpendicular to the muscle fiber direction using another program, I-DEAS. An analysis of variance was performed.

RESULTS: The ventral component of the levator muscle of women with major defects had a 36% smaller cross-sectional area, and women with minor defects had a 29% smaller cross-sectional area compared with the women with no defects (P<.001). In the dorsal component, there were significant differences in cross-sectional area according to defect status (P=.03); women with major levator defects had the largest cross-sectional area compared with the other defect groups. For each defect severity category (none, minor, major), there were no significant differences in cross-sectional area between women with and those without prolapse.

CONCLUSION: Women with visible levator ani defects on magnetic resonance imaging had significantly smaller cross-sectional areas in the ventral component of the pubic portion of the muscle compared with women with intact muscles. Women with major levator ani defects had larger cross-sectional areas in the dorsal component than women with minor or no defects.


© 2006 The American College of Obstetricians and Gynecologists



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