Racial differences in pelvic morphology among asymptomatic nulliparous women as seen on three-dimensional magnetic resonance images.

Objective: Compare pelvic morphology between asymptomatic African-American and white nulliparous women.

Study Design: Resting supine T2-weighted magnetic resonance (MR) images were obtained in 12 African-American (AA) and 10 white American (WA) women without pelvic floor dysfunction. Three-dimensional models were reconstructed from the MR images by a masked investigator, and predefined bony and soft tissue pelvic floor parameters were measured and compared. Nonparametric statistics were used, with significance considered at P < .05.

Results: Subjects were similar in age and body mass index. Levator ani volume was significantly greater in the AA versus the WA group (mean = 26.8 vs 19.8 cm3, P = .002). The levator-symphysis gap was smaller in the AA (left-18.2, right-18.8 mm) versus the WA group (22.4, 22.6 mm, P = .003, .048) on the left and right. Significant differences were seen in bladder neck position, urethral angle, and the pubic arch angle.

Conclusion: The increased muscle bulk and closer puborectalis attachment seen among the African-American nulliparous women may impact the development of pelvic floor dysfunction. These findings need further study.