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.