Levator plate angle in women with pelvic organ prolapse compared to women with normal support using dynamic MR imaging.
OBJECTIVE
The purpose of this study was to determine whether the levator plate is (1) horizontal in women with normal support, (2) different between women with and without prolapse, (3) related to levator hiatus and perineal body descent.


METHODS
Cohorts of cases with prolapse at least 1 cm below the hymen and normal controls with all points 1 cm or more above the hymen were prospectively enrolled in a study of pelvic organ support to be of similar age, race, and parity. Subjects underwent supine midsagittal dynamic magnetic resonance imaging (MRI) during Valsalva. Levator plate angle (LPA) was measured relative to a horizontal reference line. Levator hiatus length (LH) and perineal body location (PB) were also measured. Student t tests and Pearson correlation coefficients (r) were performed.


RESULTS
Sixty-eight controls and 74 cases were analyzed. During Valsalva, controls had a mean LPA of 44.3 degrees . Cases, compared to controls, had 9.1 degrees (21%) more caudally directed LPA (53.4 degrees vs 44.3 degrees , P < .01), 15% larger LH length (7.8 cm vs 6.8 cm, P < .01), and 24% more caudal PB location (6.8 cm vs 5.5 cm, P < .01). Increases in LPA were correlated with increased LH length (r = 0.42, P < .0001) and PB location (r =.51, P < .0001).


CONCLUSIONS
The measured levator plate angle in women with normal support is 44.3 degrees . During Valsalva, women with prolapse have a modest (9.1 degrees) though statistically greater levator plate angle compared to controls. This larger angle showed moderate correlation with larger levator hiatus length and greater displacement of the perineal body in women with prolapse compared to controls.
Hsu
Yvonne
Y
Department of Obstetrics and Gynecology, School of Public Health, University of Michigan, Ann Arbor, MI, USA. yvonneh@med.umich.edu
Summers
Aimee
A
Hussain
Hero K
HK
Guire
Kenneth E
KE
Delancey
John O L
JO
D000009:Abdominal Muscles / Q000473:pathology* / Q000503:physiopathology; D000368:Aged; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D015588:Observer Variation; D017773:Pelvic Floor; D011446:Prospective Studies; D012146:Rest; D014596:Uterine Prolapse / Q000175:diagnosis* / Q000503:physiopathology; D014636:Valsalva Maneuver