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Dysfunctional Uterine Bleeding

Abnormal uterine bleeding is a common presenting problem in gynae OPD. Dysfunctional uterine bleeding (DUB) is defined as abnormal uterine bleeding in the absence of organic disease. Dysfunctional uterine bleeding is the most common cause of abnormal vaginal bleeding during a woman's reproductive years. Dysfunctional uterine bleeding can have a substantial financial and quality-of-life burden. It affects women's health both medically and socially.
Pathophysiology

The normal menstrual cycle is 28 days and starts on the first day of menses. During the first 14 days (follicular phase) of the menstrual cycle, the endometrium thickens under the influence of oestrogen. In response to rising oestrogen levels, the pituitary gland secretes follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which stimulate the release of an ovum at the midpoint of the cycle. The residual follicular capsule forms the corpus luteum.

After ovulation, the luteal phase begins and is characterized by production of progesterone from the corpus luteum. Progesterone matures the lining of the uterus and makes it more receptive to implantation. If implantation does not occur, in the absence of human chorionic gonadotropin (HCG), the corpus luteum dies, accompanied by sharp drops in progesterone and oestrogen levels. Hormone withdrawal causes vasoconstriction in the spiral arterioles of the endometrium. This leads to menses, which occurs approximately 14 days after ovulation when the ischemic endometrial lining becomes necrotic and sloughs. 

Terms frequently used to describe abnormal uterine bleeding

  • Menorrhagia - Prolonged (>7 d) or excessive (>80 mL daily) uterine bleeding occurring at regular intervals

  • Metrorrhagia - Uterine bleeding occurring at irregular and more frequent than normal intervals

  • Menometrorrhagia - Prolonged or excessive uterine bleeding occurring at irregular and more frequent than normal intervals

  • Intermenstrual bleeding - Uterine bleeding of variable amounts occurring between regular menstrual periods

  • Midcycle spotting - Spotting occurring just before ovulation, typically from declining estrogen levels

  • Postmenopausal bleeding - Recurrence of bleeding in a menopausal woman at least 6 months to 1 year after cessation of cycles

  • Amenorrhea - No uterine bleeding for 6 months or longer

Dysfunctional uterine bleeding is a diagnosis of exclusion. It is ovulatory or anovulatory bleeding, diagnosed after pregnancy, medications, iatrogenic causes, genital tract pathology, malignancy, and systemic disease have been ruled out by appropriate investigations. Approximately 90% of dysfunctional uterine bleeding cases result from anovulation, and 10% of cases occur with ovulatory cycles.3

 

Anovulatory dysfunctional uterine bleeding results from a disturbance of the normal hypothalamic-pituitary-ovarian axis and is particularly common at the extremes of the reproductive years. When ovulation does not occur, no progesterone is produced to stabilize the endometrium; thus, proliferative endometrium persists. Bleeding episodes become irregular, and amenorrhea, metrorrhagia, and menometrorrhagia are common. Bleeding from anovulatory dysfunctional uterine bleeding is thought to result from changes in prostaglandin concentration, increased endometrial responsiveness to vasodilating prostaglandins, and changes in endometrial vascular structure.

 

In ovulatory dysfunctional uterine bleeding, bleeding occurs cyclically, and menorrhagia is thought to originate from defects in the control mechanisms of menstruation. It is thought that, in women with ovulatory dysfunctional uterine bleeding, there is an increased rate of blood loss resulting from vasodilatation of the vessels supplying the endometrium due to decreased vascular tone, and prostaglandins have been strongly implicated. Therefore, these women lose blood at rates about 3 times faster than women with normal menses. 

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