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. Anovulatory 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. The cause can be psychological stress, weight (obesity, anorexia, or a rapid change), exercise, endocrinopathy, neoplasm, drugs, or it may be otherwise unknown. Diagnosis Diagnosis of AUB starts with a medical history and physical examination. 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. 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. Ultrasound is specifically recommended in those over the age of 35 or those in whom bleeding continues despite initial treatment. Laboratory assessment of thyroid stimulating hormone (TSH), pregnancy, and chlamydia is also recommended. More extensive testing might include an MRI and endometrial sampling. 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. The PALM-COEIN system may be used to classify the uterine bleeding. Management Treatment depends on the underlying cause. Options may include hormonal