What Causes Heavy Menstrual Bleeding?
A “Normal” Menstrual Cycle
The lining of the uterus responds to hormones made in the ovary. The pituitary gland secretes a hormone which causes the egg follicles in the ovary to make estrogen. Estrogen causes the uterus lining to thicken. When ovulation occurs, a second hormone (progesterone) is secreted by the ovary. This causes the lining of the uterus to become spongy. After fourteen days the progesterone and estrogen levels fall and then the uterus lining sheds in a menstrual period.
Heavy Menses Can be Caused by Hormonal Problems
Hormone imbalance can cause irregular bleeding. It is usually possible to evaluate this by history and by using methods to evaluate ovulation. If a woman is on birth control pills, then her hormones are controlled by the pills. Estrogen replacement after menopause can also cause bleeding.
Irregular Ovulation Can Cause Heavy Menses
If ovulation does not occur, the ovary will continue making estrogen, causing the uterus lining to keep thickening. This can lead to a late menstrual period followed by irregular bleeding and spotting. This can also result in endometrial polyps, or in extreme long-standing cases, cancer of the lining of the uterus.
Any type of stress can interfere with normal ovulation. Fortunately this will usually be temporary, and rarely requires treatment. If ovulation is repeatedly irregular it can be treated with progesterone, which causes the lining of the uterus to shed regularly. Birth control pills may often accomplish the same goal.
Uterine Problems Can Cause Heavy Menses
Approximately 30% of women have fibroid tumors. These growths are almost always benign, and most of the time do not cause symptoms. Fibroids typically grow larger as a woman ages, and usually decreases in size after menopause. They can range in size from pea-size to larger than a grapefruit. Often a uterus will grow many fibroids.
Endometrial polyps are growths in the lining of the uterus that are very common, and usually benign. They can hang from the lining of the uterus like figs or appear to be rather flat. Polyps may result from long-term estrogen stimulation. This can occur as a result of extended periods of no ovulating or from taking estrogen hormones without any progesterone.
When the lining of the uterus grows into the wall of the uterus, the condition is called adenomyosis. Normally, when the uterine lining sheds during a menstrual period the blood is free to drain out through the cervix. When the lining goes into the muscle some of the blood may be trapped. This may cause severe cramps and heavy bleeding. This can cause the walls of the uterus to thicken and the uterus to become enlarged.
Other Causes of Heavy Menses
If a pregnancy is abnormal, such as a tubal pregnancy or impending miscarriage, any bleeding may be interpreted as being from a menstrual period rather than a complication of pregnancy. Because pregnancy is such a common cause of abnormal bleeding, a pregnancy test should be one of the first tests that are performed.
Thyroid disorders can be another cause of heavy menstrual bleeding. Also, any disorder in which the blood does not clot normally may be the cause. A physician can test for these problems if they are suspected to be part or all of the cause for heavy menstrual bleeding.
This information is provided for your information. It is not medical advice and should not be relied upon as a substitute for visiting your doctor. If you need medical care, or have any questions, please contact your obstetrician-gynecologist.
