Symptoms include vaginal bleeding that occurs irregularly, at abnormal frequency, lasts excessively long, or is more than normal.^[1] Normal frequency of periods is 22 to 38 days.^[1][3] Variation in the length of time between cycles is typically less than 21 days.^[3] Bleeding typically last less than nine days and blood loss is less than 80 mL.^[1][3] Excessive blood loss may also be defined as that which negatively affects a person's quality of life.^[2] Bleeding more than six months after menopause is also a concern.^[4]

The causes of AUB are divided into nine groups: uterine polyps, fibroids, adenomyosis, cancer, blood clotting disorders, problems with ovulation, endometrial problems, healthcare induced, and not yet classified.^[3] More than one category of causes may apply in an individual case.^[3] Healthcare induced causes may include side effects of birth control.^[3]

The underlying mechanism is often a hormonal disturbance: reduced levels of progesterone cause high levels of prostaglandin F2-alpha and cause abnormally heavy flow as progesterone stabilizes the endometrium and inhibits synthesis of prostaglandin F2-alpha; increased levels of tissue plasminogen activator (t-PA), a fibrinolytic enzyme, lead to more fibrinolysis.^{[citation needed]}

Ovulatory edit

Ten percent of cases occur in women who are ovulating, but progesterone secretion is prolonged because estrogen levels are low. This causes irregular shedding of the uterine lining and break-through bleeding. Some evidence has associated ovulatory DUB with more fragile blood vessels in the uterus. It may represent a possible endocrine dysfunction, resulting in menorrhagia or metrorrhagia. Mid-cycle bleeding may indicate a transient estrogen decline, while late-cycle bleeding may indicate progesterone deficiency.^{[citation needed]}

Anovulatory edit

About 90% of DUB events occur when ovulation is not occurring (anovulatory DUB). Anovulatory menstrual cycles are common at the extremes of reproductive age, such as early puberty and perimenopause (period around menopause). In such cases, women do not properly develop and release a mature egg. When this happens, the corpus luteum, which is a mound of tissue that produces progesterone, does not form. As a result, estrogen is produced continuously, causing an overgrowth of the uterus lining. The period is delayed in such cases, and when it occurs menstruation can be very heavy and prolonged. Sometimes anovulatory DUB is due to a delay in the full maturation of the reproductive system in teenagers. Usually, however, the mechanisms are unknown.^{[citation needed]}

The cause can be psychological stress, weight (obesity, anorexia, or a rapid change), exercise, endocrinopathy, neoplasm, drugs, or it may be otherwise unknown.^{[citation needed]}

Diagnosis of AUB starts with a medical history and physical examination.^[2] Normal menstrual bleeding patterns vary from woman to woman, so the medical history covers specific details about the woman's individual menstrual bleeding pattern, such as its predictability, length, volume, and whether she experiences cramps or other pain. The healthcare provider will also check to see whether she or any family members have any potentially related health conditions, and whether she is taking medication that might increase or decrease menstrual bleeding, such as herbal supplements, hormonal contraceptives, over-the-counter drugs such as aspirin, or blood thinners.^[8]

Medical tests include a blood test, to see whether the abnormal bleeding has caused anemia, and a pelvic ultrasound, to see whether the abnormal bleeding is caused by a structural problem, such as a uterine fibroid.^[2] Ultrasound is specifically recommended in those over the age of 35 or those in whom bleeding continues despite initial treatment.^[4] Laboratory assessment of thyroid stimulating hormone (TSH), pregnancy, and chlamydia is also recommended.^[8]

More extensive testing might include an MRI and endometrial sampling.^[2] Endometrial sampling is recommended in those over the age of 45 who do not improve with treatment and in those with intermenstrual bleeding that persists.^[2] The PALM-COEIN system may be used to classify the uterine bleeding.^[8]

Treatment depends on the underlying cause.^[3][2] Options may include hormonal birth control, gonadotropin-releasing hormone (GnRH) agonists, tranexamic acid, NSAIDs, and surgery such as endometrial ablation or hysterectomy.^[1][5] Polyps, adenomyosis, and cancer are generally treated by surgery.^[2] Iron supplementation may be needed.^[2]

The terminology "dysfunctional uterine bleeding" is no longer recommended.^[3] Historically dysfunctional uterine bleeding meant there was no structural or systemic problems present.^[3] In AUB underlying causes may be present.^[3]

About one-third of all medical appointments with gynecologists involve AUB, with the proportion rising to 70% in the years around menopause.^[8]

• Merck Manual Abnormal Uterine Bleeding