Ultrasound modalities and age-specific normative findings in pediatric and adolescent gynecology.

Ultrasound is the first-line modality for imaging the female gynecological organs in children and adolescents. Its interpretation relies on understanding the physiological changes in organ appearance from birth through puberty. This narrative review considers different ultrasound approaches including transabdominal, transvaginal, transrectal, transperineal, Doppler and three-dimensional ultrasound, and when magnetic resonance imaging may add useful information. It then describes how normal uterine, ovarian, and endometrial appearances change across development. Although the evidence is drawn mainly from cross-sectional studies using different equipment, measurement methods, and reporting approaches, the studies describe a broadly consistent developmental pattern. A central practical message emerges: thresholds and diagnostic criteria derived from adults translate poorly to the developing pelvis, so interpretation rests not on memorizing cut-offs but on knowing what to expect at each age and stage, and on recognizing how wide normal physiological variation is. The review also identifies the principal evidence gaps: sparse data at the youngest ages, limited representation of diverse populations, an absence of longitudinal studies, a reliance on adult-derived criteria for diagnosing pathology such as adnexal masses, adenomyosis and endometriosis, and the lack of a standardized reporting framework. It then sets out priorities for future research.