Abnormal uterine bleeding (AUB) refers to irregular bleeding between menstrual periods, prolonged periods, or very heavy menstrual flow, often due to hormonal changes, fibroids, or other structural causes. Diagnosis typically involves ultrasound and may require additional tests like hysteroscopy or biopsy, while treatment options are tailored to individual circumstances, including age and fertility desires. Common symptoms include soaking through tampons or pads every hour and bleeding lasting over seven days.