The periodic sloughing off of the uterine lining (endometrium) during a woman*s reproductive years.
Approximately once a month, women of childbearing age experience a bloody vaginal discharge known as menstruation. The onset of menstruation (menarche) usually occurs sometime between 11 and 15 years of age (average age is 12.8). The average menstrual cycle lasts approximately 28 days, although anywhere between 20 and 36 days is considered normal. (The menstrual cycle is measured from the first day of one period to the first day of the following period.) Monthly menstruation continues until a woman reaches menopause, which ordinarily occurs between the ages of 45 and 50.
Menstruation is the result of complex hormonal interactions. During the typical menstrual cycle, the ovaries produce estrogen and progesterone, which cause ovulation to occur and the lining of the uterus (endometrium) to build up. If sexual intercourse takes place and a sperm fertilizes the egg (ovum) as it moves through the fallopian tube, the fertilized egg will implant itself in the endometrium and begin developing into a fetus. If no fertilized egg has implanted itself in the endometrium, the secretion of progesterone from the ovaries declines, which causes the endometrium to be sloughed off. Menstruation usually occurs two weeks after ovulation, although irregular periods
Dysfunctional uterine bleeding (DUB) is heavy or prolonged bleeding, usually anovulatory. Heavy bleeding is defined as more than 15 soaked pads or tampons per period, and prolonged bleeding as bleeding that lasts for more than 8-10 days. Although DUB is very common in the first couple of years after menarche, it can be very frightening and should always be reported to a physician. DUB accompanied by dizziness and low blood pressure should be considered a medical emergency. DUB has a number of causes, including hormonal imbalance, sexually transmitted diseases, ectopie pregnancy, hypothyroidism, ovarian cysts, and uterine fibroids or polyps.
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Author Info: Gail B. Slap M.D., Thomson Gale, Detroit, Gale Encyclopedia of Childhood and Adolescence, 1998 |