Quantitative analyses of variability in normal vaginal shape and dimension on MR images

INTRODUCTION AND HYPOTHESIS We present a technique for quantifying inter-individual variability in normal vaginal shape, axis, and dimension, and report findings in healthy women. METHODS Eighty women (age: 28∼70 years) with normal pelvic organ support underwent supine, multi-planar proton-density MRI. Vaginal width was assessed at five evenly-spaced locations, and vaginal axis, length, and surface area were quantified via ImageJ and MATLAB. RESULTS The mid-sagittal plane angles, relative to the horizontal, of three vaginal axes were 90 ± 11, 72 ± 21, and 41 ± 22° (caudal to cranial, p < 0.001). The mean (± SD) vaginal widths were 17 ± 5, 24 ± 4, 30 ± 7, 41 ± 9, and 45 ± 12 mm at the five locations (caudal to cranial, p < 0.001). Mid-sagittal lengths for anterior and posterior vaginal walls were 63 ± 9 and 98 ± 18 mm respectively. The vaginal surface area was 72 ± 21 cm(2) (range: 34 ∼ 164 cm(2)). The coefficient of determination between any demographic variable and any vaginal dimension did not exceed 0.16. CONCLUSIONS Large variations in normal vaginal shape, axis, and dimensions were not explained by body size or other demographic variables. This variation has implications for reconstructive surgery, intravaginal and surgical product design, and vaginal drug delivery