Uterine fibroids are tumors or lumps made of muscle cells and other tissue that grow within the wall of the uterus. Fibroids may grow as a single tumor or in clusters.
A single fibroid can be less than one inch in size or can grow to eight inches across or more. A bunch or cluster of fibroids can also vary in size.
Where do uterine fibroids grow?
Most fibroids grow within the wall of the uterus. Health care providers put fibroids into three groups based on where they grow:
- Submucosal (pronounced sub-myou-co-sul) fibroids grow just underneath the uterine lining.
Some fibroids grow on stalks (also called peduncles, pronounced ped-uncles) that grow out from the surface of the uterus, or into the cavity of the uterus.
What are the symptoms of uterine fibroids?
Many women don't feel any symptoms with uterine fibroids. But fibroids can cause the following symptoms:
- Heavy bleeding or painful periods
- Bleeding between periods
- Feeling "full" in the lower abdomen - sometimes called "pelvic pressure"
- Urinating often (results from a fibroid pressing on the bladder)
- Pain during sex
- Lower back pain
- Reproductive problems, such as infertility, multiple miscarriages, and early onset of labor during pregnancy
What causes uterine fibroids?
Currently, we know little about what causes uterine fibroids. Scientists have a number of theories, but none of these ideas explains fibroids completely. Most likely, fibroids are the end result of many factors interacting with each other. These factors could be genetic, hormonal, environmental, or a combination of all three. Once we know the cause or causes of fibroids, our efforts to find a cure or even prevent fibroids will move ahead more quickly.
Does having uterine fibroids mean that a woman will be infertile or unable to have children?
In some cases, fibroids can prevent a woman from getting pregnant through natural methods. However, advances in treatments for fibroids and infertility have greatly improved the chances for a woman to get pregnant, even if she has uterine fibroids.
Researchers are still looking into what role, if any, uterine fibroids play in infertility. Currently, though, there are few answers. One study's results suggest that only submucosal fibroids have a negative impact on fertility (Pritts 2001), but these results are not yet confirmed. The relationship between fibroids and infertility remains a very active research area.
Does having uterine fibroids mean a woman will need a hysterectomy (removing the uterus)?
Hysterectomy is not the best option for every woman with uterine fibroids. If a woman wants to have children, then she would want to avoid this treatment. Likewise, if a woman isn't showing symptoms of uterine fibroids, or her fibroids are small, she may have better results from pain medications or hormone treatments. Doctors are also exploring less-invasive surgical treatments for fibroids that save the uterus. See the What are the treatments for uterine fibroids? section of this fact sheet for more information about less-invasive treatments.
In some cases, though, a hysterectomy is the best method of treatment. If you have uterine fibroids and are thinking about having a hysterectomy, make sure you talk over all features of the surgery with your doctor and your family. Having a hysterectomy means that you will no longer be able to have children. This process cannot be reversed, so be certain about your choice before having the surgery.
Keep in mind that the physical scars of the procedure may heal quickly, but some of the effects of hysterectomy are long-lasting. You may want to talk to women who have had the procedure before you decide to have your surgery. Many health care centers, women's clinics, and hospitals offer support groups for women who have had, or are in the process of having a hysterectomy.
Who gets uterine fibroids?
Most of the time, fibroids grow in women of childbearing age. Research studies estimate that doctors diagnose up to 30% (Newbold et al 2000) of women of childbearing age with uterine fibroids; but, because some women show no symptoms of fibroids, as many as 77% of women of childbearing age could have the condition, without knowing it (Cramer & Patel 1990). We don't know exactly how many new cases of fibroids occur in a year, nor do we know how many women have fibroids at any one time.
There have also been reports of rare cases in which young girls who have not yet started their periods (pre-pubertal) had small fibroids.
Researchers now recognize several risk factors for uterine fibroids.
- Current statistics place African-American women at three-to-five times greater risk than white women for fibroids.
- Women who are overweight or obese for their height (based on body mass index or BMI) are also at slightly higher risk for fibroids than women who are average weight for their height.
- Women who have given birth appear to be at lower risk for uterine fibroids.
But, because we don't know what causes fibroids, we also don't know what increases or reduces their growth.
How do I know that I have uterine fibroids?
Unless you start to have symptoms, you probably won't know that you have uterine fibroids.
Sometimes, health care providers find fibroids during a routine gynecological exam.
During this exam, the health care provider checks out the size of your uterus by putting two fingers of one hand into the vagina, while applying light pressure to your abdomen with the other hand.
If you have fibroids, your uterus may feel larger-than-normal; or, if you have fibroids, your uterus may extend into places it should not.
If your health care provider thinks that you have fibroids, he or she may use imaging technology -machines that create a picture of the inside of your body without surgery- to confirm the diagnosis. Some common types of imaging technology include:
Ultrasound, which uses sound waves to form the picture;
Magnetic resonance imaging or MRI, which uses magnets and radio waves to build the picture;
X-rays, which use a form of electromagnetic radiation to "see" into the body; and
CT or "cat"-scan, which takes x-rays of the body from many angles to provide a more complete image.
Sometimes, health care providers use a combination of these technologies. Sometimes, however, the only way to confirm the presence of uterine fibroids is through surgery.
Laparoscopy (pronounced lapp-are-ah-skoe-pee) - In this procedure, the surgeon makes a small cut into the abdomen, after inflating it with a harmless gas; then, using a small viewing instrument with a light in it, the doctor can look for fibroids.
Your health care provider may suggest a procedure called a hysteroscopy (pronounced hiss-tur-ah-skoe-pee), which involves inserting a camera on a long tube through the vagina directly into the uterus to see the fibroids.
Keep in mind that because these are surgical procedures, you will need time to recover from them. However, the amount of recovery time you'll need may vary.
What are the treatments for uterine fibroids?
Health care providers consider a number of things when recommending treatment for fibroids, including:
- Does the woman have symptoms of uterine fibroids?
- Does she want to become pregnant?
- How large are the fibroids?
What is the woman's age?
If a woman has uterine fibroids, but shows no symptoms or has no problems, she may not need any treatment. The provider will check the fibroids at a woman's routine gynecological exam to see if they have grown.
If a woman has pain now-and-then or feels mild symptoms, her health care provider may suggest pain medication, ranging from over-the-counter remedies to strong prescription drugs.
If a woman has many symptoms or feels pain often, she may benefit from medical therapy - that is, therapy using certain medications rather than surgery. Keep in mind that many medications have side effects, some of them serious.
One way to reduce symptoms of uterine fibroids is using one of a group of hormones called gonadotropin releasing hormone agonists (GnRHa). These hormones block the body from making the hormones that cause women to menstruate or have their periods. If you have symptoms, have health conditions that make surgery less advisable, and are near menopause or do not want children, you may receive GnRHa therapy to treat your fibroids.
Antihormonal agents, like mifepristone, also slow or stop the growth of fibroids.
Medical therapy is often used before a woman has surgery for her fibroids.
This therapy offers only temporary relief from the symptoms of fibroids; once a woman goes off the therapy, her fibroids often grow back.
If a woman has moderate symptoms of fibroids, surgery may be the best form of treatment.
Myomectomy removes only the fibroids and leaves the healthy areas of the uterus in place. This procedure can preserve a woman's ability to have children.
Hysterectomy is used when a woman's fibroids are large, or has heavy bleeding, and she is either near or past menopause, or doesn't want children. Hysterectomy is the only sure way to cure uterine fibroids. In general, recovery time from a hysterectomy is one to two months. Health care providers now have hysterectomy options that differ in how invasive they are.
Abdominal hysterectomy is a procedure that involves a cut into the abdomen to remove the uterus.
Vaginal hysterectomy is less invasive because the doctor reaches the uterus through the vagina, instead of making a cut into the abdomen. This procedure may not be an option if the fibroids are very large.
Are there any developing treatments for uterine fibroids?
Currently, researchers are looking into other methods of treating uterine fibroids. Keep in mind that these methods are not yet standard treatments for uterine fibroids, which means your health care provider may not offer them, or your insurance company may not pay for them. But, it's possible that research to confirm the safety and effectiveness of these experimental treatments will advance our ability to treat uterine fibroids. These developing treatments include:
In cryomyolysis (pronounced cry-oh-my-oh-lie-sis), the health care provider puts a freezing agent directly on the fibroids to make them shrink.
Uterine Artery Embolization (UAE) cuts off the blood supply to the uterus and the fibroids, which makes them shrink. Recovery time for UAE is much shorter than for hysterectomy. But, this option limits a woman's ability to have children.
Do uterine fibroids lead to cancer?
Uterine fibroids are not cancerous. Fibroids are not associated with cancer; they rarely develop into cancer (in less than 0.1% of cases). Having fibroids does not increase your risk for uterine cancer (Levy et al 2000).
Do uterine fibroids ever go away?
For the most part, fibroids stop growing or shrink once a woman passes menopause. However, this is not the case for all women. Some studies suggests a relationship between hormone replacement therapy or HRT, used to reduce the symptoms of menopause, and uterine fibroids, but the nature of this relationship is still unclear (Schwartz et al 2000). More research is needed in this area.
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