Skip to main content

URMC Logo

URMC / Encyclopedia / Content

Uterine Fibroids

What are uterine fibroids?

Fibroids are firm, compact tumors made of smooth muscle cells and fibrous connective tissue. They develop in the uterus. It is estimated that between 20% to 50% of women of reproductive age have fibroids, although not all are diagnosed. Some estimates state that up to 30% to 77% of women will develop fibroids sometime during their childbearing years. Although Only about one-third of these fibroids are large enough to be detected by a healthcare provider during a physical exam.

In more than 99% of fibroid cases, the tumors are not cancer. These tumors are not linked to cancer and do not increase a woman's risk for uterine cancer. They may range in size, from the size of a pea to the size of a softball or small grapefruit.

What causes uterine fibroid tumors?

The cause of uterine fibroids is not known. But, it’s thought that each tumor develops from an abnormal muscle cell in the uterus. This cell multiplies rapidly because of the effect of estrogen.

Who is at risk for uterine fibroids?

Women who are nearing menopause are at the greatest risk for fibroids. This is because of their long exposure to high levels of estrogen. Women who are obese and of African-American heritage also seem to be at an increased risk. The reasons for this are not clearly understood.

Other risk factors: 

  • Diet high in red meat
  • Family history of fibroids
  • High blood pressure

What are the symptoms of uterine fibroids?

Some women who have fibroids have no symptoms, or have only mild symptoms. Other women have more severe, disruptive symptoms. The following are the most common symptoms for uterine fibroids. Symptoms of uterine fibroids may include:

  • Heavy or prolonged periods
  • Abnormal bleeding between periods
  • Pelvic pain, caused as the tumor presses on pelvic organs
  • Frequent urination
  • Low back pain
  • Pain during intercourse
  • A firm mass, often located near the middle of the pelvis, which can be felt by your healthcare provider

How are uterine fibroids diagnosed?

Fibroids are most often found during a routine pelvic exam. Your healthcare provider may feel a firm, irregular pelvic mass during an abdominal exam. Other tests may include:

  • X-ray. Electromagnetic energy used to produce images of bones and internal organs onto film.
  • Transvaginal ultrasound. An ultrasound test using a small instrument, called a transducer, that is placed in the vagina.
  • MRI. A noninvasive procedure that produces a two-dimensional view of an internal organ or structure.
  • Hysterosalpingography. X-ray exam of the uterus and fallopian tubes that uses dye. It is often done to rule out tubal obstruction.
  • Hysteroscopy. Visual exam of the canal of the cervix and the interior of the uterus using a viewing instrument (hysteroscope) inserted through the vagina.
  • Endometrial biopsy. A procedure in which a sample of tissue is taken through a tube inserted into the uterus.
  • Blood test. This is to check for iron-deficiency anemia if heavy bleeding is caused by the tumor.

How are uterine fibroids treated?

Since most fibroids stop growing or may even shrink as you approach menopause, your healthcare provider may simply suggest "watchful waiting." With this approach, your healthcare provider monitors your symptoms carefully to make sure that there are no significant changes and that the fibroids are not growing.

If your fibroids are large or cause significant symptoms, treatment may be necessary. Treatment will be discussed with you by your healthcare provider based on:

  • How old you are
  • Your overall health and past health
  • How sick you are
  • How well you can handle specific medicines, procedures, or therapies
  • How long your condition is expected to last
  • Your opinion or preference
  • Your desire for pregnancy

In general, treatment for fibroids may include:

  • Hysterectomy. This is the surgical removal of the entire uterus. Fibroids remain the number one reason for hysterectomies in the U.S.
  • Conservative surgical therapy. Conservative surgical therapy uses a procedure called a myomectomy. With this approach, fibroids are removed, but the uterus stays intact. This may allow a future pregnancy.
  • Gonadotropin-releasing hormone agonists (GnRH agonists). This approach lowers your estrogen level. This triggers a "medical menopause." Sometimes GnRH agonists are used to shrink the fibroid, making surgery easier.
  • Anti-hormonal medicines. Certain medicines oppose estrogen (such as progestin and Danazol), and seem to work to treat fibroids. Anti-progestins, which block the action of progesterone, are also sometimes used.
  • Uterine artery embolization. Also called uterine fibroid embolization, uterine artery embolization (UAE) is a newer technique. The arteries supplying blood to the fibroids are identified, then embolized (blocked off). The embolization cuts off the blood supply to the fibroids, thus shrinking them. Healthcare providers continue to look at the long-term implications of this procedure on fertility and regrowth of the fibroid tissue.
  • Anti-inflammatory painkillers. This type of medicine is often effective for women who have occasional pelvic pain or discomfort.

In some cases, the heavy or prolonged periods, or the abnormal bleeding between periods, can lead to iron-deficiency anemia. This also requires treatment.

What are the complications of uterine fibroids?

Uterine fibroids may have effects on the reproductive system, causing infertility, increased risk of miscarriage, or adverse pregnancy outcomes.

Key points about uterine fibroids

  • Uterine fibroids are firm, compact tumors that are made of smooth muscle cells and fibrous connective tissue that develop in the uterus. 
  • Fibroids are not cancer and do not increase a woman's risk for uterine cancer.
  • It is not known what causes fibroids.
  • Women who are nearing menopause are at the greatest risk for fibroids. This is because of their long exposure to high levels of estrogen.
  • Symptoms may include heavy and prolonged periods, bleeding between periods and pelvic pain.
  • Fibroids are most often found during a routine pelvic exam.
  • If treatment is needed, it may include medicines or surgery.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

  • Know the reason for your visit and what you want to happen.
  • Before your visit, write down questions you want answered.
  • Bring someone with you to help you ask questions and remember what your provider tells you.
  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.
  • Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
  • Ask if your condition can be treated in other ways.
  • Know why a test or procedure is recommended and what the results could mean.
  • Know what to expect if you do not take the medicine or have the test or procedure.
  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your provider if you have questions.

Medical Reviewers:

  • Burd, Irina, MD, PhD
  • Freeborn, Donna, PhD, CNM, FNP