Description

• Bleeding that is excessive in flow, outside of regular menstrual cycles, or occurs daily for >8 days
• Adolescents typically do not establish regular ovulatory cycles until their mid to late teens, therefore “normal” periods can last 2 to 7 days, can occur every 21 to 45 days, and blood loss can vary from 20 to 80 mL per cycle.
• Abnormal uterine bleeding (AUB) can vary in presentation from menses that lasts for weeks and varies in flow followed by long periods of amenorrhea to shorter but heavy flow menses, occurring more frequently.
• In teens, AUB most commonly results from an immature hypothalamic–pituitary–ovarian (HPO) axis and consequent anovulatory cycles.

Epidemiology

• AUB commonly occurs within 5 to 7 years after menarche, most often in the first 2 years when >50% of cycles are anovulatory.
• Later age at menarche is associated with longer duration of anovulatory cycles.
• Most females who experience anovulatory cycles do not develop AUB.

Risk Factors

Pathophysiology

• In anovulatory cycles, failure to ovulate results in a lack of progesterone production due to corpus luteum absence.
• Without the secretory effect of progesterone from the corpus luteum, endometrial proliferation continues because of unopposed estrogen.
• The thickened endometrium eventually outgrows support from the basal endometrium, resulting in sloughing of the highest endometrial levels. Alternatively, cyclic estrogen withdrawal may occur, which will lead to sloughing of the endometrium in the absence of progesterone.
• As subsequent levels of endometrium are shed, bleeding increases. Profuse bleeding may result when the basal endometrium is exposed.
• Anovulatory cycles occur as a result of maturity, PCOS, pregnancy, thyroid dysfunction, or hypothalamic dysfunction as a result of weight loss, obesity, autoimmune or other chronic disease, or exercise.
• AUB can also result or be exacerbated by underlying blood dyscrasia or infection.