US of the pediatric female pelvis: a clinical perspective.

When investigating pelvic pathologic conditions in female pediatric patients, one needs to be aware of the developmental changes that take place around puberty. The prepubertal uterus is thin, with a fundus equal in size to the cervix. Owing to the hormonal stimulation of puberty, the uterus enlarges and the fundus becomes prominent. The ovaries are demonstrated with ultrasonography (US) at all ages. Ovarian volume increases after 6 years of age. Microcystic follicles are normally seen throughout childhood. US is the modality of choice for imaging the pediatric female pelvis. The main indications for pelvic US in the pediatric age group are pubertal precocity or pubertal delay, pelvic pain or pelvic masses, and ambiguous genitalia. Vaginal bleeding in the prepubertal child can be due to a vaginal foreign body, vaginal rhabdomyosarcoma, or precocious puberty. Common causes of primary amenorrhea in teenagers include gonadal dysgenesis (Turner syndrome) and müllerian (uterovaginal) anomalies. Pelvic pain or pelvic masses in pediatric patients can be due to ovarian torsion, hemorrhagic ovarian cyst, pelvic inflammatory disease, or ectopic pregnancy.