Dysfunctional Abnormal Uterine Bleeding (AUB)

Descriptive text is not available for this imageBASICS

DESCRIPTION

  • Adolescents typically do not establish regular menstrual cycles until their late teens; thus, “normal” periods can last 2 to 7 days, occur every 21 to 45 days, and vary from 20 to 80 mL of blood loss per cycle.
  • Abnormal uterine bleeding (AUB) is menstrual bleeding that is excessive in flow, outside of established regular (ovulatory) menstrual cycles, or lasts >8 continuous days.
  • AUB can have widely variable bleeding patterns at presentation, ranging from menses lasting for weeks with variable flow followed by long periods of amenorrhea to short but heavy flow menses occurring more frequently than every 21 days.

EPIDEMIOLOGY

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

RISK FACTORS

Genetics

Patients with disorders, such as blood dyscrasias or polycystic ovary syndrome (PCOS), usually have family histories of similar disorders.

PATHOPHYSIOLOGY

  • Although there is a broad differential diagnosis, AUB during adolescence is most commonly caused by anovulation due to hypothalamic–pituitary–ovarian (HPO) axis immaturity.
  • Anovulation leads to uterine hemorrhage as the proliferative estrogen effects on the endometrial lining are unopposed by the secretory, or stabilizing, effect of progesterone from the corpus luteum.
  • As the endometrium thickens, it can slough, leaving exposed basal endometrial arterioles.
  • Alternatively, cyclic estrogen withdrawal may occur prior to established ovulatory cycles, leading to endometrial tissue sloughing.
  • Although anovulatory cycles are expected as the HPO axis matures in early to mid-adolescence, other causes of anovulatory cycles through young adulthood include pregnancy, PCOS, thyroid and other endocrine dysfunction, and hypothalamic dysfunction as a result of weight loss, obesity, excessive exercise, daily cannabis use, or autoimmune, oncologic, or other chronic disease onset.
  • AUB can also be caused or exacerbated by underlying bleeding dyscrasias, endometrial inflammation or infection, and side effects of hormonal replacement, chemotherapy, or contraception.
  • Polyps, adenomyosis, leiomyoma, and malignancy also very rarely cause AUB in teenagers and young adults.

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