Abnormal uterine bleeding (AUB), also known as (AVB) or as atypical vaginal bleeding, is vaginal bleeding from the uterus that is abnormally frequent, lasts excessively long, is heavier than normal, or is irregular. The term dysfunctional uterine bleeding was used when no underlying cause was present. Vaginal bleeding during pregnancy is excluded. Iron deficiency anemia may occur and quality of life may be negatively affected. The underlying causes may include ovulation problems, fibroids, the lining of the uterus growing into the uterine wall, uterine polyps, underlying bleeding problems, side effects from birth control, or cancer. More than one category of causes may apply in an individual case. The first step in work-up is to rule out a tumor or pregnancy. Medical imaging or hysteroscopy may help with the diagnosis. Treatment depends on the underlying cause. Options may include hormonal birth control, gonadotropin-releasing hormone (GnRH) agonists, tranexamic acid, NSAIDs, and surgery such as endometrial ablation or hysterectomy. Over the course of a year, roughly 20% of reproductive-aged women self-report at least one symptom of AUB. Signs and symptoms Symptoms include vaginal bleeding that occurs irregularly, at abnormal frequency, lasts excessively long, or is more than normal. Normal frequency of periods is 22 to 38 days. Variation in the length of time between cycles is typically less than 21 days. Bleeding typically last less than nine days and blood loss is less than 80 mL. Excessive blood loss may also be defined as that which negatively affects a person's quality of life. Bleeding more than six months after menopause is also a concern. Causes 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. More than one category of causes may apply in an individual case. Healthcare induced causes may include side effects of birth control. Mechanism 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. Ovulatory 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