Baseline dimensions of the human vagina

BACKGROUND: Vaginal anatomy has been poorly studied. This study aimed to measure baseline dimensions of the undistended vagina of women of reproductive age. METHODS: We combined baseline information collected from five clinical trials using magnetic resonance imaging (MRI) to quantify distribution of a vaginal gel. Seventy-seven MRI scans were performed on 28 women before gel application to establish baseline vaginal measurements. Average dimensions were calculated for each woman and for the population. The influence of potential covariates (age, height, weight and parity) on these dimensions was assessed. RESULTS: MRI measurements are reproducible. The SD surrounding the mean at each anatomical site, and with summary measurements, was significantly smaller with each subject compared with the population. Mean vaginal length from cervix to introitus was 62.7 mm. Vaginal width was largest in the proximal vagina (32.5 mm), decreased as it passed through the pelvic diaphragm (27.8 mm) and smallest at the introitus (26.2 mm). Significant positive associations were parity with vaginal fornix length, age with pelvic flexure width and the height with width at the pelvic flexure. CONCLUSION: No one description characterized the shape of the human vagina. Although there is variation among women, variables such as parity, age and height are positively associated with differences in baseline dimensions.