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.