AUB refers to irregular, prolonged, or excessive menstrual bleeding unrelated to pregnancy The term AUB has replaced the previous terminology of dysfunctional uterine bleeding The majority of adolescents who present to the ED with AUB will have bleeding related to anovulatory cycles Normal menstrual cycles in an adolescent may range from 21 to 45 days, though the adult menstrual cycle is generally 21 to 35 days Regular ovulatory cycles may not occur until to years after menarche, with the majority of AUB within the first 18 months after menarche being due to anovulatory cycles Bleeding that persists beyond days, recurs at intervals of fewer than 21 days, soaks greater than one pad per hour for more than hours in a row, produces large-sized clots, causes symptomatic anemia, or creates hemodynamic instability, warrants attention Ovulation typically occurs 14 days prior to the onset of menses, and the ovarian follicle forms a corpus luteum (type of functional ovarian cyst) that secretes progesterone and estradiol After ovulation, the progesterone produced by the corpus luteum promotes growth of the endometrial secretory glands and spiral blood vessels, though it also limits the ultimate thickness of the endometrium As the corpus luteum degenerates, circulating levels of estrogen and progesterone fall which lead to endometrial necrosis and menstrual sloughing, which comprises the menstrual blood flow The majority of adolescents who present with AUB experience intervals of anovulation Without ovulation, there is no progesterone secreted by the corpus luteum to promote structural integrity of the endometrium Estrogen levels secreted by the ovarian follicles may fluctuate; when large amounts are secreted, there is greater endometrial proliferation and thus heavier vaginal bleeding Clinical Manifestations History, physical, and laboratory tests help the clinician guide the severity of the patient’s vaginal bleeding Bleeding that has been occurring for days or more, at intervals more frequently than every 21 days, bleeding greater than 80 mL menstrual period, or bleeding large clots that are at least quarter sized, should be evaluated by a healthcare provider for AUB Pertinent history should also include a pregnancy risk assessment (last sexual intercourse, dates of last two menstrual periods, contraceptive use history), presence of sexual activity, or presence of any underlying platelet or bleeding disorder (e.g., thrombocytopenia, von Willebrand disease) The physical examination starts with the measurement of the patient’s vital signs, including checking for orthostatic changes in the pulse and blood pressure Pallor and symptomatic orthostasis are concerning for significant anemia Petechiae, bruising, and mucosal bleeding may indicate a bleeding disorder Signs