Architectural differences in the bony pelvis of women with and without pelvic floor disorders

To investigate the hypothesis that the architecture of the bony pelvis differs between women with and without pelvic floor disorders.

We designed a case-control study of women who had undergone magnetic resonance imaging (MRI) of the pelvis at our institution. Records were reviewed to identify women with and without pelvic floor disorders (urinary or anal incontinence, other symptoms of urinary tract dysfunction, or pelvic organ prolapse). Pelvimetry techniques were standardized. Relevant measures included transverse diameter of the inlet, angle of the pubic arch, intertuberous diameter, interspinous diameter, sacrococcygeal length, depth of sacral curvature, anteroposterior conjugate, obstetrical conjugate, and anteroposterior outlet. Multiple logistic regression analysis was used to identify women with pelvic floor disorders as a function of their pelvic dimensions, controlling for potentially confounding variables.

Subjects included 59 women with pelvic floor disorders and 39 women without pelvic floor disorders. Women with pelvic floor disorders had a wider transverse inlet, wider intertuberous diameter, wider interspinous diameter, greater sacrococcygeal length, deeper sacral curvature, and narrower anteroposterior outlet. When controlling for the confounding effects of age, race, and parity, we found that a wider transverse inlet (odds ratio 3.425) and a shorter obstetrical conjugate (odds ratio 0.233) were significantly associated with pelvic floor disorders.

A wide transverse inlet and narrow obstetrical conjugate are associated with pelvic floor disorders. We speculate that these features of bony pelvic architecture may predispose the patient to neuromuscular and connective tissue injuries, leading to the development of pelvic floor disorders.