What causes persistent menstrual bleeding in a 12-year-old girl?

In a 12-year-old girl, persistent menstrual bleeding (menorrhagia or prolonged menstruation) is commonly caused by factors such as deficiency of qi and blood or endocrine imbalance. She should visit a hospital for diagnostic evaluation—including pelvic ultrasound and a sex hormone panel (six-item hormonal assay)—to identify the underlying cause. Once diagnosed, treatment should be guided by a physician and may include herbal or pharmaceutical interventions aimed at tonifying qi and nourishing blood. During treatment, maintain local hygiene by frequently changing underwear and sanitary pads, and ensure adequate warmth for the abdominal area.