Dysfunctional Uterine Bleeding
Dysfunctional uterine bleeding (DUB) is abnormal uterine bleeding. The diagnosis of DUB should be used only when all other organic and structural causes for abnormal vaginal bleeding have been ruled out. It is a diagnosis of exclusion and, in fact, is rarely used when a patient is fully evaluated.
The most common cause of abnormal vaginal bleeding is anovualtion. A normal menstrual cycle occurs every 21-38 days with menstruation for 2-7 days. The average blood loss is 35-150 cc, which represents 8 or fewer soaked pads per day with usually no more than 2 heavy days. Menorrhagia is the term for excessive bleeding with a normal interval. Metrorrhagia is bleeding that is irregular or too frequent. Menometrorrhagia is excessive bleeding at irregular intervals.
As noted, over 90% of DUB results from anovulation, and 10% occurs with ovulatory cycles. During an anovulatory cycle, the corpus luteum fails to form, which causes failure of normal cyclical progesterone secretion. This results in continuous unopposed production of estradiol, stimulating overgrowth of the endometrium. The growing endometrium eventually outgrows its blood supply, leading to necrosis and sloughing of the endometrium. With ovulatory DUB, prolonged progesterone secretion causes irregular shedding of the endometrium.
A carefully obtained history usually identifies the cause of the abnormal uterine bleeding and appropriate treatments can then be initiated.
