Vaginal opening measurement in prepubertal girls.

Normative, age-indexed data regarding the size of the vaginal opening in prepubertal girls have not been previously reported, to our knowledge. Measurement of the apparent transverse diameter of the vaginal opening was done in 273 prepubertal girls as part of their routine health assessment. Vaginal opening diameter tended to enlarge with age and to be larger in the supine knee-chest position than in the supine frog-leg position. An opening greater than 4 mm was distinctly rare.