NICHD

EUNICE KENNEDY SHRIVER

NATIONAL INSTITUTE

OF CHILD HEALTH AND

HUMAN DEVELOPMENT

U.S. Department of

Health and Human Services

National Institutes of Health

Uterine Fibroids

Fast Facts:

Common name: Uterine Fibroids

Medical name: Uterine Leiomyoma (pronounced YOU­ter­in

lee­oh­my­OH­mah)

Number of women

affected:

At least 25 percent of women in the United

States have clinically symptomatic fibroids,

which means they have symptoms that are

typical of fibroids (Crum 1999); estimates

suggest fibroids could affect as many as 77

percent of women in the United States

(Cramer & Patel 1990).

Common symptoms: May include heavy periods, bleeding

between periods, pelvic pain or “fullness,”

reproductive problems, including infertility and

multiple miscarriages.

Common treatments: Some women do not receive treatment

because they do not have symptoms. Other

treatments include: pain medication, medical

therapy, and surgery to remove just the

fibroid, to cut off the blood supply to the

fibroid, or to remove the entire uterus.

Doctors are exploring less­invasive surgeries

and hormone therapy as other options.

Does this disorder affect

fertility/childbearing?

Most women who have fibroids do not have

problems with fertility and are able to get

pregnant. In some cases, fibroids can prevent

a woman from getting pregnant naturally.

Uterine fibroids are the most common, non­cancerous tumors in women

of childbearing age. They are the cause of more than 200,000

hysterectomies every year (Easterday et al 1983). They have no known cause

and only a few treatment options. Uterine fibroids not only affect the

women who have them, but they also impact the partners, spouses, and

families of these women, sometimes to a great degree. Despite the fact

that they may affect one­quarter of all the women in the United States,

fibroids continue to baffle health care providers and scientists.

The Eunice Kennedy Shriver National Institute of Child Health and

Human Development (NICHD), part of the National Institutes of Health

(NIH) within the U.S. Department of Health and Human Services (DHHS),

is trying to learn more about uterine fibroids, through research into their

causes and treatments. As part of this research, NICHD scientists are

exploring genetics, hormones, the immune system, and environmental

factors that may play a role in starting the growth of fibroids and/or in

continuing that growth. This information could lead to a cure for uterine

fibroids that does not involve taking out the uterus. Someday, health

care providers may even be able to prevent uterine fibroids from

growing at all.

www.nichd.nih.gov
 
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What are uterine fibroids?
 

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 sub­myou­co­sul)

fibroids grow just underneath the uterine

lining.

•	 Intramural (pronounced in­tra­myur­ul)

fibroids grow in between the muscles of the

uterus.

•	 Subserosal (pronounced sub­sir­oh­sul)

fibroids grow on the outside of the uterus.

Some fibroids grow on stalks that grow out from

the surface of the uterus, or into the cavity of the

uterus. These are called pedunculated

(pronounced ped­un­koo­LAY­ted) fibroids.

Submucosal Intramural

Peduncle

Subserosal Subserosal

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

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U T E R I N E F I B R O I D S

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.

Who gets uterine fibroids?

Most of the time, fibroids grow in women of

childbearing age. Research studies estimate

that health care providers diagnose up to 30

percent (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 percent 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 (pre­pubertal) had small fibroids.

Researchers have also found that fibroids

sometimes run in families (Treloar 1992).

Researchers now recognize several risk factors

for uterine fibroids.

• Current statistics place African American

women at three­ to five­times 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

decreases the risk.

* For more information on the BMI, go to http://www.nhlbi.nih.gov.

Does having uterine fibroids mean

that I will be infertile or unable to

have children?

Most women who have fibroids do not have

problems with fertility and are able to get

pregnant. 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

I will need a hysterectomy?

Hysterectomy (removal of the uterus) is not the

best option for every woman with uterine

fibroids. If you want to have children, then you

would want to avoid this treatment. Likewise, if

you don’t have symptoms of uterine fibroids, or

your fibroids are small, you may have better

results from pain medications or hormone

treatments. Health care providers are also

exploring less­invasive 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.

In some cases, though, a hysterectomy is the

best method of treatment. If you have uterine

fibroids and are thinking about hysterectomy,

make sure you talk over all features of the

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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 long­lasting. 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 hysterectomies.

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

larger­than­normal; or, if you have fibroids,

your uterus may extend into places that 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;

•	 X­rays, which use a form of electromagnetic

radiation to “see” into the body; and

•	 CT or “cat”­scan, which takes x­rays 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 lapp­are­ah­skoepee)—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

hiss­tur­ah­skoe­pee), 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?
 

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U T E R I N E F I B R O I D S

If you have uterine fibroids, but show no

symptoms or problems, you may not need any

treatment. Your health care provider will check

the fibroids at your routine gynecological exam

to see if they have grown. Also, because fibroids

rely on hormones to grow, your fibroids may

decrease in size during/after menopause.

If you have pain now­and­then or feel mild

symptoms, your health care provider may

suggest pain medication, ranging from

over­the­counter remedies to stronger

prescription drugs.

Medical Therapy

If you have many symptoms or feel pain often,

you 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, such as 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 you go off the

therapy, fibroids often grow back.

Surgical Therapy

If you have moderate symptoms of fibroids,

surgery may be the best form of treatment.

Surgery can be a major or a minor procedure.

Talk to your health care provider about the

different types of surgery, the possible risks of

the procedure, and the side effects.

•	 Myomectomy removes only the fibroids and

leaves the healthy areas of the uterus in place.

This procedure can preserve your ability to

have children. Sometimes a laparoscope is

used to see inside the abdomen during this

procedure. A hysteroscope may be used to

see the size, shape, and location of the

fibroids inside the uterine lining. The surgeon

may also use the instrument to remove the

fibroid.

•	 Hysterectomy is used if your fibroids are large,

you have heavy bleeding, and you are either

near or past menopause or don’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. If

you are pre­menopausal, talk to your doctor

about keeping your ovaries. The ovaries make

hormones that help maintain bone health and

sexual health. Sometimes surgeons use a

laparoscope to see inside the uterus during

hysterectomy.

� 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.

•	 Uterine Artery Embolization (UAE)—also

called Uterine Fibroid Embolization or UFE—

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. Because this procedure can

affect how the ovaries function and can limit

fertility, health care providers do not

recommend UAE for women who want to

have children.

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Are there 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 may advance our

ability to treat uterine fibroids. These

developing treatments include:

•	 MRI­guided ultrasound surgery uses a highintensity ultrasound beam to send high

temperatures to the fibroids to make them

shrink. The MRI scanner helps to visualize the

fibroid, and the ultrasound sends out sound

waves to destroy the fibroid.

• Some health care providers use lasers to

remove a fibroid or to cut off the blood supply

to the fibroid, making it shrink.

Do uterine fibroids lead to cancer?

Uterine fibroids are not cancerous. Fibroids are

not associated with cancer; they rarely develop

into cancer (in fewer than 0.1 percent of cases).

Fibroids do not increase your risk for uterine

cancer (Levy et al 2000).

Do uterine fibroids ever go away?

In most cases, fibroids stop growing or shrink

once a woman passes menopause. But, 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.

Is research being done to learn more

about uterine fibroids?

The NICHD continues to study and learn about

uterine fibroids. The NICHD established a

Reproductive Medicine­Gynecology Program

within its Reproductive Sciences Branch to

support research on women’s health conditions

that aren’t cancerous, including uterine fibroids.

In 1998, the NICHD established the Women’s

Reproductive Health Research Career

Development Centers. These Centers support

obstetricians and gynecologists in becoming

researchers, so that they can study topics on

women’s health. In 2004­2005, the NICHD

funded 20 new and competing continuation

Centers at institutions throughout the country.

In addition to these Centers, the NICHD’s

Reproductive Sciences Branch also supports

research on uterine fibroids and on other topics

that affect women’s health, including research

on environmental factors, genetics, and

diseases that affect the reproductive health of

men and women. Long­term goals of this

research include understanding how fibroids

develop and grow, and finding more effective,

conservative treatments. Such findings will help

preserve the fertility and reproductive health of

all women.

The Division of Intramural Research (DIR) at the

NICHD also supports research on these topics.

DIR scientists are studying the basic causes of

uterine fibroids, as well as the potential of

certain drugs for treating them. For more

information on DIR research on fibroids, visit

http://fibroids.nichd.nih.gov/general.html.

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In October 1999, researchers from the NICHD

joined scientists from the National Institute of

Environmental Health Sciences, the DHHS

Office of Women's Health, the Society for

Women’s Health Research, and Wyeth­Ayerst

Pharmaceuticals to hold a conference on

uterine fibroids. The report, titled Women’s

Health and the Environment: The Next Century

—Advances in Uterine Leiomyoma Research

(2000), is available at

http://ehpnet1.niehs.nih.gov/docs/2000/

suppl­5/toc.html.

In addition, the Agency for Healthcare Research

and Quality issued an evidence­based report

about managing uterine fibroids in 2001. This

report reviewed the available literature on the

benefits, risks, and costs of uterine fibroid

treatments in the United States and provided

recommendations for future research (AHRQ

2001). The report is posted at

http://www.ahrq.gov/clinic/utersumm.htm.

In February 2005, the DHHS and the NIH

sponsored Advances in Uterine Leiomyoma

Research: 2nd International Congress, in

Bethesda, Maryland. This two­day conference,

which involved members of the academic,

clinical, and medical communities that take part

in fibroid research, allowed experts to exchange

scientific information, outline research needs,

and provide recommendations for future

research directions. The report summarizing this

meeting is in preparation.

The efforts of the NICHD, NICHD­supported

scientists, and other researchers will continue

until we know the causes, treatments, and,

someday, the cures for uterine fibroids.

References

Crum, CP. (1999). The female genital tract. In RS

Cotran, V Kumar, & T Collins (Eds.), Pathologic Basis

of Disease. Philadelphia, PA: WB Saunders.

Cramer, SF, & Patel, A. (1990). The frequency of

uterine leiomyomas. American Journal of Clinical

Pathology, 94, 435­438.

Easterday, CL, Grimes, DA, & Riggs, JA. (1983).

Hysterectomy in the United States. Obstet Gynecol,

62, 203­212.

Pritts, EA. (2001). Fibroids and infertility: A systematic

review of the evidence. Obstet Gynecol Surv,

Aug;58(8), 483­491.

Newbold, RR, DiAugustine, RP, Risinger, JI, Everitt, JI,

Walmer, DK, Parrott, EC, & Dixon, D. (2000).

Advances in uterine leiomyoma research: Conference

overview, summary, and future research

recommendations. Environ Health Perspect,

108(suppl 5), 769­773.

Levy, B, Mukherjee, T, & Hirschhorn, K. (2000).

Molecular cytogenetic analysis of uterine

leiomyoma and leiomyosarcoma by comparative

genomic hybridization. Cancer Genet Cytogenet,

Aug;121(1):1­8.

Schwartz, S, Marshall, L, & Baird, D. (2000).

Epidemiologic contributions to understanding the

etiology of uterine leiomyomata. Environ Health

Perspect, 108(Suppl 5), 821­827.

Treloar, SA, Martin, NG, Dennerstein, L, Raphael, B,

& Heath, AC. (1992). Pathways to hysterectomy:

Insights from longitudinal twin research. Am J

Obstet Gynecol, 167(1), 82­88.

Women’s Health and the Environment: The Next

Century—Advances in Uterine Leiomyoma

Research, Conference Proceedings, October 7­8,

1999. (2000). Environ Health Perspec, 108(suppl 5),

767­853.

Management of Uterine Fibroids. (2001). Summary,

Evidence Report/Technology Assessment: Number

34. AHRQ Publication No. 01­E051. Agency for

Healthcare Research and Quality, Rockville, MD.

http://www.ahrq.gov/clinic/utersumm.htm

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Where can I go for more information about uterine fibroids?

The NICHD supports and conducts research on topics related to the health of children,

adults, families, and populations, including uterine fibroids. The mission of the NICHD is to

ensure that every person is born healthy and wanted, that women suffer no harmful

effects from the reproductive process, and that all children have the chance to fulfill their

potential for a healthy and productive life, free of disease or disability, and to ensure the

health, productivity, independence, and well­being of all people through optimal

rehabilitation. You can contact the NICHD at:

NICHD Information Resource Center

Phone: 1­800­370­2943 (TTY: 1­888­320­6942)

Mail: P.O. Box 3006, Rockville, MD 20847

Fax: 1­877­760­5947

E­mail: NICHDInformationResourceCenter@mail.nih.gov

Internet: http://www.nichd.nih.gov

These organizations also provide information about the diagnosis and treatment of uterine

fibroids and offer support to women and their families affected by this disease.

• American College of Obstetricians and Gynecologists (ACOG) is the nation's leading

group of professionals providing health care for women. For more information, contact:

Phone: (202) 863­2518
 Mail: 409 12th Street, SW, P.O. Box 96920, Washington, DC 20024­2188
 Fax: (202) 484­1595
 E­mail: resources@acog.org
 Internet: http://www.acog.org
 

•	 American Society of Reproductive Medicine (ASRM) is an organization devoted to

advancing knowledge and expertise in reproductive medicine and biology. For more

information, contact:

Phone: (205) 978­5000
 Mail: 1209 Montgomery Hwy., Birmingham, Alabama 35216­2809
 Fax: (205) 978­5005
 E­mail: asrm@asrm.org
 

Internet: http://www.asrm.org
 

In addition, the National Library of Medicine, part of the NIH, offers information about uterine

fibroids at http://www.nlm.nih.gov/medlineplus/uterinefibroids.html.

NICHD

National Institute of Child Health
 

& Human Development
 

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NIH Pub. No. 05­7103

December 2005