Pubertal maturation of the internal genitalia: an ultrasound evaluation of 166 healthy girls

Pelvic ultrasound is an important tool in the management of children with disturbances of pubertal development; interpretation requires an understanding of the normal relationship between maturation of internal genitalia and the appearance of secondary sex characteristics. We performed pelvic ultrasound examinations in 166 healthy females aged 6.4-25.4 years, and related uterine and ovarian volumes and size of follicles to age and pubertal stage. We demonstrated growth of the uterus and ovaries before the appearance of breast development and pubic hair growth. In prepubertal girls, uterine and ovarian growth was related to height (p = 0.008 and p = 0.010, respectively). From breast stages 1-5, median uterine and ovarian volumes increased from 1.6 ml to 43 ml, and from 1.2 ml to 7.3 ml, respectively (p < 0.0001). Uterine growth continued several years after menarche. Postmenarcheal uterine growth was related to the number of years after menarche (p < 0.001), but not to height, weight or age. Follicles were seen in 86% of prepubertal girls and in 99% of pubertal girls. Follicles up to 8 mm in diameter were observed in prepubertal girls. Maturation of the internal genitalia begins before the onset of clinical puberty, and extends well into the second decade.