Anovulatory bleeding is the most common form of noncyclic uterine bleeding.5 Patients often seek medical care to regulate their menstrual cycle or improve fertility. All women of reproductive age should have a pregnancy test when presenting with irregular menstrual bleeding. Anovulation may be secondary to physiologic or pathologic causes. It is common at menarche and in the perimenopausal period. During adolescence, ovulatory menstrual cycles may not be regular for a year or more after menarche.5 Overall, the frequency of ovulation is related to the time since menarche

and the age at menarche. In the year following menarche, there may be an immature feedback mechanism in the hypothalamic-pituitary-ovarian (HPO) axis whereby the LH surge needed for ovulation does not occur. During perimenopause, anovulat-ory cycles may occur owing to a declining quality and quantity of ovarian follicles. As ovarian function declines, estrogen secretion continues and progesterone secretion decreases. Chronic anovulatory cycles and unopposed estrogen secretion lead to en-dometrial proliferation and increased risk of polyps, endometrial hyperplasia, and carcinoma.

Anovulation also may occur at any time during the reproductive years due to a pathologic cause. The most common causes of nonphysiologic ovulatory dysfunction and their prevalence rates5 are:

• Hypothalamic amenorrhea (10%)

• Hyperprolactinemia (10%)

Premature ovarian failure (10%)

PCOS, while responsible for 70% of the cases of ovulatory dysfunction, occurs in ap-

proximately 4% of women. etiology

Anovulation may result from a problem at any level of the HPO axis. In addition to various physiologic life stages such as adolescence, perimenopause, pregnancy, and

5 27

lactation, other causes of anovulation include: '

• Hyperandrogenic anovulation (PCOS, congenital adrenal hyperplasia, androgen-producing tumors)

• Hypothalamic dysfunction (anorexia nervosa, physical or emotional stress)

• Hyperprolactinemia


• Primary pituitary disease

• Premature ovarian failure



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