What causes abnormal vaginal bleeding in women who are ovulating regularly?
Abnormal vaginal bleeding in women who are ovulating regularly most commonly involves excessive, frequent, irregular, or decreased bleeding. Some of the common conditions that produce each of these symptoms are discussed below.
Excessively heavy menstrual bleeding (menorrhagia)
Excessively heavy menstrual bleeding, called menorrhagia, is menstrual bleeding of greater than about eight tablespoons per month (normal menstrual bleeding produces between two and eight tablespoons per cycle). The most common pattern of menorrhagia is excessive bleeding that occurs in regular menstrual cycles and with normal ovulation.
There are several important reasons that menorrhagia should be evaluated by a doctor. First, menorrhagia can cause a woman substantial emotional distress and physical symptoms, such as severe cramping. Second, the blood loss can be so severe that it causes a dangerously lowered blood count (anemia), which can lead to medical complications and symptoms such as dizziness and fainting. Third, there can be dangerous causes of menorrhagia that require more urgent treatment.
Benign (noncancerous) causes of menorrhagia include:
Though not common, menorrhagia can be a sign of endometrial cancer. A potentially precancerous condition known as endometrial hyperplasia can also result in abnormal vaginal bleeding. This situation is more frequent in women who are over the age of 40.
Although there are many causes of menorrhagia, in most women, the specific cause of menorrhagia is not found even after a full medical evaluation. These women are said to have dysfunctional uterine bleeding. Although no specific cause of abnormal vaginal bleeding is found in women with dysfunctional uterine bleeding, there are treatments available to reduce the severity of the condition.
Irregular vaginal bleeding; menstrual periods that are too frequent (polymenorrhea)
Menstrual periods that are abnormally frequent (polymenorrhea) can be caused by certain sexually transmitted diseases (STDs) (such as Chlamydia or gonorrhea) that cause inflammation in the uterus. This condition is called pelvic inflammatory disease. Endometriosis is a condition of unknown cause that results in the presence of uterine lining tissue in other locations outside of the uterus. This can lead to pelvic pain and polymenorrhea. Sometimes, the cause of polymenorrhea is unclear, in which case the woman is said to have dysfunctional uterine bleeding.
Menstrual periods at irregular intervals (metrorrhagia)
Irregular menstrual periods (metrorrhagia) can be due to benign growths in the cervix, such as cervical polyps. The cause of these growths is usually not known. Metrorrhagia can also be caused by infections of the uterus (endometritis) and the use of birth control pills (oral contraceptives). Sometimes after an evaluation, a woman's doctor might determine that her metrorrhagia does not have an identifiable cause and that further evaluation is not necessary at that time.
Perimenopause is the time period approaching or around menopause. It often is characterized by irregular menstrual cycles, including menstrual periods at irregular intervals and variations in the amount of blood flow. Menstrual irregularities may precede the onset of true menopause (defined as the absence of periods for one year) by several years.
Decreased amount or duration of menstrual flow (hypomenorrhea)
An overactive thyroid function (hyperthyroidism) or certain kidney diseases can both cause hypomenorrhea. Oral contraceptive pills can also cause hypomenorrhea. It is important for women to know that lighter, shorter, or even absent menstrual periods as a result of taking oral contraceptive pills do not indicate that the contraceptive effect of the oral contraceptive pills is inadequate. In fact, many women appreciate this "side effect" of oral contraceptives.
Bleeding between menstrual periods (intermenstrual bleeding)
Women who are ovulating normally can experience light bleeding (sometimes referred to as "spotting") between menstrual periods. Hormonal birth control methods (oral contraceptive pills or patches), as well as IUD use for contraception, may sometimes lead to light bleeding between periods. Psychological stress, certain medications such as anticoagulant drugs, and fluctuations in hormone levels may all be causes of light bleeding between periods. Other conditions that cause abnormal menstrual bleeding, or bleeding in women who are not ovulating regularly also can be the cause of intermenstrual bleeding.