Quantification of levator ani cross-sectional area differences between women with and those without prolapse.
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.


CONCLUSIONS
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.


METHODS
II-2.
Hsu
Yvonne
Y
University of Michigan, Ann Arbor, Michigan, USA. yvonneh@med.umich.edu
Chen
Luyun
L
Huebner
Markus
M
Ashton-Miller
James A
JA
DeLancey
John O L
JO
D016022:Case-Control Studies; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D017773:Pelvic Floor / Q000033:anatomy & histology / Q000473:pathology*; D014596:Uterine Prolapse / Q000473:pathology*