Chapter 33 Dysfunctional Uterine Bleeding
Dysfunctional uterine bleeding (DUB) is defined as abnormal uterine bleeding (AUB) in women between menarche and menopause that cannot be attributed to medications, blood dyscrasias, systemic diseases, trauma, uterine neoplasms, or pregnancy. This form of AUB is almost always caused by aberrations in the hypothalamic-pituitary-ovarian hormonal axis resulting in anovulation. The diagnosis of DUB is made by excluding other treatable causes of AUB.
The bleeding is generally from a proliferative, or discordant (mixed), endometrium. In most cases, it is associated with anovulatory or oligo-ovulatory ovarian cycles (e.g., polycystic ovary syndrome), and estrogen levels are frequently unopposed by progesterone. On occasion, it occurs with apparently normal ovulatory cycles. It is one of the most common problems dealt with in the gynecologic clinic or private office.
Abnormal bleeding patterns are defined in Box 33-1. Taken together, these abnormal patterns are sometimes designated as menometrorrhagia.
Most DUB occurs during the years around the menarche (11 to 14 years of age) or menopause (45 to 50 years of age). During the perimenopausal years, the anovulatory bleeding is mainly caused by the declining functional capacity of the ovary. In adolescence, the anovulatory bleeding may be caused by a failure of the hypothalamic-pituitary system to respond to the positive feedback effect of estrogen.
Abnormalities of menstrual bleeding are thought to be associated with alterations in endometrial vascular homeostasis. A normally efficient menstrual cycle is discussed in detail in Chapter 4, and the normal events are briefly summarized as follows.
First, gradually increasing estrogen levels support and maintain the growth of endometrium during the proliferative phase of the cycle. The proliferative phase is variable in length, but it generally lasts 13 days from the onset of menses to the luteinizing hormone surge. The increasing level of estrogen supports growth, prevents breakthrough bleeding, and stimulates an increase in endometrial progesterone receptors.
Second, about 24 hours after the luteinizing hormone surge, ovulation occurs, and the corpus luteum forms. It produces estrogen and progesterone in increasing amounts and lasts for about 14 days unless an intervening pregnancy prolongs it by secretion of human chorionic gonadotropin (hCG). With the demise of the corpus luteum, the levels of estrogen and progesterone fall precipitously, and the decidual portion of the endometrium desquamates.
Third, during the luteal phase of the endometrial cycle, there is a marked increase in tissue levels of prostaglandin F2α, which is a powerful vasoconstrictor, and this eventually leads to endometrial ischemia. The process allows for a complete sloughing of the outer two thirds of the endometrium and avoids prolonged menstruation. During anovulatory cycles, the resulting nonsecretory endometrium contains less prostaglandin and is less apt to initiate an efficient menstrual period of short duration. The unopposed estrogenic effect is likely to result in cycles of irregular duration and prolonged menses. With repeated cycles of unopposed estrogen, endometrial hyperplasia or even cancer may develop.
Diagnosis
The diagnosis of DUB is usually made by excluding other causes of AUB. A possible unexpected pregnancy should always be ruled out initially. Box 33-2 lists possible causes of AUB to be considered. A pelvic examination must be performed to verify that the source of bleeding is uterine and not the result of a cervical, rectal, vaginal, vulvar, or urethral lesion. Iatrogenic causes such as oral contraceptive–induced breakthrough bleeding or bleeding associated with an intrauterine device should be considered. Dyscrasias of the blood such as von Willebrand’s disease should be ruled out. Systemic diseases such as liver, renal, or thyroid conditions may represent treatable causes of AUB. Trauma, although unusual, is an occasional cause of vaginal and even uterine bleeding and should be considered at the time of the pelvic examination. Organic causes of AUB include tumors, infections, and complications of pregnancy. Benign tumors and growths
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