What is abnormal uterine bleeding?
Under normal circumstances, a woman's uterus sheds a limited amount of blood during each menstrual period. Bleeding that occurs between menstrual periods, or excessive bleeding that occurs during menstruation, is generally considered abnormal uterine bleeding. Once a woman enters menopause and menstrual cycles have ended, any bleeding, other than the small amounts that can occur in women on hormone replacement therapy, is considered abnormal.
What causes abnormal uterine bleeding?
While most conditions that cause abnormal uterine bleeding can occur at any age, some are more likely to occur at particular times in a woman's life. In many women, a hormone imbalance causes bleeding. These women may have too much estrogen or not enough progesterone. Polyps or fibroids (small and large growths) in the uterus can also cause bleeding. Cancer of the uterus and infection of the cervix are other causes of bleeding. Sometimes a thyroid problem causes bleeding.
These are just a few of the problems that can cause abnormal uterine bleeding. These problems can occur at any age. But the likely cause of abnormal uterine bleeding depends on your age.
From childhood to adulthood: Bleeding in girls who have not yet begun to menstruate is always abnormal and can be caused by trauma, the presence of a foreign body, irritation of the genital area, or urinary tract problems. Bleeding can also occur as a result of sexual abuse.
Many girls have episodes of irregular bleeding during the first few years after their periods begin and until a normal hormonal cycle and regular ovulation is established. If bleeding persists beyond this time, or if the bleeding is heavy, see your doctor.
Girls and women who use oral contraceptives may experience "breakthrough" bleeding between periods. If this occurs during the first months of oral contraceptive use, it may be due to changes in the lining of the uterus. If it persists for more than several months, a different oral contraceptive may be prescribed. Breakthrough bleeding can also happen if the oral contraceptive is not taken regularly. If this occurs, the breakthrough bleeding may be an indication that the pill is not effective. Additional contraception may be necessary until the oral contraceptives are taken on a regular schedule and the breakthrough bleeding stops. If a woman experiences persistent breakthrough bleeding, see your doctor.
Abnormal bleeding in this age group can also be caused by pregnancy, bleeding disorders, some medical illnesses, and infection.
Adult Women up through their 30s: A common cause of abnormal bleeding in young women and teenagers is pregnancy. Many women have bleeding in the first few months of a normal pregnancy. Birth control pills can also cause abnormal bleeding. If an egg isn't released (ovulation) during your menstrual cycle, you might have abnormal bleeding — either light spotting between periods or heavy bleeding during your period.
For premenopausal women many different conditions can cause abnormal bleeding such as abrupt changes in hormone levels at the time of expected ovulation can cause vaginal spotting, or small amounts of bleeding. As noted above, breakthrough bleeding can occur in women who use oral contraceptives.
In women who don't ovulate (anovulatory women), irregular changes in hormone levels can cause bleeding to occur intermittently and in varying amounts. Although anovulation is most common when periods first begin and during perimenopause, it can occur at any time during the reproductive years.
Among women who ovulate normally, some experience excessive blood loss during their periods or bleed between periods. The most common causes of such bleeding are uterine fibroids or polyps. These irregular growths and benign tumors are composed of uterine tissue that distort the structure of the uterus and lead to abnormal uterine bleeding. Fibroids and polyps can also occur in anovulatory women.
Other causes of abnormal uterine bleeding in premenopausal women include:
- Cancer of the endometrium (lining of the uterus) or benign precancerous endometrial lesions
- Endometritis or inflammation of the endometrium
- A pelvic or vaginal infection
- Clotting disorders such as von Willebrand's disease, platelet abnormalities, or problems with clotting factors
- Some systemic illnesses such as hypothyroidism, liver disease, or chronic renal disease
Women in their 40s and early 50s: Before menstruation stops completely and menopause begins, a woman passes through a period called perimenopause. During perimenopause, normal hormonal cycling begins to change and ovulation may be inconsistent. While estrogen secretion continues, progesterone secretion declines. These hormonal changes can cause the endometrium to proliferate or produce excess tissue, and increase the chance that polyps or fibroids that cause abnormal bleeding will develop. Women in perimenopause are also at risk for other conditions that cause abnormal bleeding, including cancer, infection, and systemic illnesses. Further evaluation is indicated if a woman experiences persistent irregular menstrual cycles or an episode of profuse bleeding.
In addition, because women in perimenopause ovulate some of the time, pregnancy is still possible and can be a cause of abnormal bleeding. And, since many women in perimenopause remain on oral contraceptive agents, breakthrough bleeding can occur as well.
In the years before menopause, women have months when they don't ovulate. This can cause abnormal uterine bleeding. Thickening of the lining of the uterus (called the endometrium) is another cause of bleeding in women in their 40s. This thickening can be a warning of endometrial cancer. In women in their 40s and early 50s, it's important to make sure endometrial cancer isn't the cause of abnormal bleeding.
During and after menopause:
Hormone replacement therapy is often a cause of uterine bleeding after menopause. Other causes include a thickened endometrium and uterine cancer. Uterine cancer is more common in older women than in younger women. But cancer is not always the cause of abnormal uterine bleeding. Many other problems can cause bleeding after menopause. Some of the most common causes of abnormal bleeding during menopause include:
- Atrophy or thinning of the tissue lining the vagina and uterus
- Cancer of the uterine lining or endometrium
- Polyps or fibroids
- Endometrial hyperplasia or the rapid growth of extra endometrial tissue
- Infection of the uterus
- Use of blood thinners or anticoagulants
- Side effects of radiation therapy
What tests can find the cause of abnormal uterine bleeding?
In addition to a careful history and physical examination, laboratory tests and diagnostic procedures may be used to identify the cause of abnormal bleeding. If you could be pregnant, your doctor may order a pregnancy test. If your bleeding is heavy, your doctor may want to check your blood count to make sure you don't have anemia (low iron) from the blood loss. Depending on your age, your doctor may order some of the following tests:
- ultrasound - An ultrasound uses sound waves to assess an organ's physical shape and structure. In a transvaginal ultrasound, a small ultrasound probe is inserted into the vagina so that it is closer to the uterus and can provide a clearer image of uterine contents. A transvaginal ultrasound is a minimally invasive way to determine whether abnormal uterine structures, or signs of excessive endometrial growth, are present. However, because it cannot distinguish between different types of structural abnormalities, further testing may be necessary if any are found.
- In premenopausal women, a pregnancy test is usually performed.
- cervical culture - If there is a vaginal discharge suggesting the presence of an infection, a cervical culture may be performed.
- Lab tests - Blood tests may also be conducted to determine whether there are problems with blood clotting or other systemic conditions, such as hypothyroidism, liver disease, or kidney problems.
- ovulation tests - Because hormonal irregularities can contribute to abnormal uterine bleeding, tests may be performed in premenopausal women to determine whether they ovulate (produce an egg) during each monthly cycle. For example, a woman may be asked to record when her periods begin and end for several months and to note any premenstrual changes, like cramps or breast tenderness, that occur. She may also be asked to record her temperature with a special thermometer that is sensitive to slight changes in body temperature. Progesterone, which is released at the time of ovulation, causes a slight increase in temperature, and regular monitoring will detect whether this occurs on a cyclical basis. In addition, her progesterone level may be measured with a blood test.
- endometrial biopsy - An endometrial biopsy is often performed in women over age 35 to rule out endometrial cancer or unusual endometrial growths. A biopsy may also be performed in women younger than 35 if they have risk factors for endometrial cancer. Risks include obesity, chronic anovulation, history of breast cancer, tamoxifen use or a family history of breast cancer or some other cancers. It's done by putting a thin plastic tube (called a catheter) into your uterus. A tiny piece of the uterine lining is taken out and sent to a lab for testing. The test will show if you have cancer or a change in the cells. A biopsy can be done in the doctor's office and causes only mild pain.
- MRI - Magnetic Resonance Imaging is non-invasive and uses a magnetic field and radio waves to visualize organs. It is sometimes used to determine the presence of fibroids or other structural abnormalities.
- hysteroscopy - A thin tube with a tiny camera in it is put into your uterus. The camera lets your doctor see the inside of your uterus. If anything abnormal shows up, your doctor can get a biopsy. In a hysteroscopy, a small scope is threaded through the cervix and into the uterus. Air or fluid is injected to expand the uterus and to allow better visualization of the uterine contents. Tissue samples may be obtained from targeted areas. Sedation with regional anesthesia or general anesthesia is used to minimize discomfort during the procedure.
- Dilation and curettage (D&C) - In a D&C, the cervix or opening of the uterus is dilated, and instruments are inserted and used to remove endometrial or uterine tissue. A D&C is one of the more invasive procedures used to assess the endometrium, and usually requires anesthesia. It may be used to supplement the tissue obtained with an endometrial biopsy. It can sometimes be used as a treatment for prolonged or excessive bleeding that is due to hormonal changes and that is unresponsive to other treatments.
How is abnormal uterine bleeding treated?
The treatment depends on the cause. If the cause is a hormone imbalance, your doctor may suggest you take birth control pills or progesterone. If the bleeding is related to hormone replacement therapy, your doctor may change the amount of estrogen you take. If a thyroid problem is causing your bleeding, treatment of that problem itself may stop the bleeding. You may need surgery if you have endometrial hyperplasia (an overgrowth of normal cells in the uterus) or cancer. Oral contraceptives are often used to treat uterine bleeding that is due to hormonal changes or hormonal irregularities. Oral contraceptives or intrauterine contraceptive devices that secrete progestin, may be used in anovulatory women to establish regular bleeding cycles and prevent excessive growth of the endometrium. In ovulating women, they may be used to treat excessive menstrual blood loss. Nonsteroidal anti-inflammatory drugs (NSAIDS) may also be helpful in reducing blood loss in these women. During perimenopause, oral contraceptives or other hormonal therapy may be used to regulate menstruation and prevent excessive growth of the endometrium.