Comparison of the Vaginal and Labial Dimensions of Ethnic Chinese and Western Nullipara.

Introduction and hypothesis: Vaginal dimensions have clinical and surgical implications. We sought to quantify the differences between vaginal and labial dimensions in healthy ethnic Chinese and Western women with normal pelvic organ support.

Methods: This is a cross-sectional study of a convenience sample of ethnic Chinese nulliparas (n = 33) and Western nulliparas (n = 33) recruited for research purposes. For each subject, magnetic resonance imaging was used to quantify the vaginal and labial dimensions. Specifically, we identified the anterior and posterior vaginal wall, the outline of the cervix in the mid-sagittal and coronal planes, and the distance from the labia majora to the hymenal ring at the urethral meatus.

Results: There were significant differences in age and weight between groups. Substantial variation in vaginal and labial dimensions was found within each group. The vaginal and labial dimensions of ethnic Chinese women ranged from 9-21% smaller than those of Western women; In the ethnic Chinese group, increasing weight and BMI correlated with greater labial distance (r = 0.66 and r = 0.63 respectively); as did height and the distance from the vaginal opening to the cervical os (r = 0.5). In the Western group, only weight correlated with the labial distance (r = 0.51).

Conclusions: Significant group differences in vaginal and labial dimensions were found, with the dimensions of Chinese nulliparas being up to 21% smaller than those of Western nulliparas.