Uterine Fibroids

Definition

Uterine fibroids are noncancerous growths of the uterus that often appear during childbearing years. Also called leiomyomas (lie-o-my-O-muhs) or myomas, uterine fibroids aren't associated with an increased risk of uterine cancer and almost never develop into cancer.

Uterine fibroids develop from the smooth muscular tissue of the uterus (myometrium). A single cell divides repeatedly, eventually creating a firm, rubbery mass distinct from nearby tissue. The growth patterns of uterine fibroids vary — they may grow slowly or rapidly, or they may remain the same size. Some fibroids go through growth spurts, and some may shrink on their own. Many fibroids that have been present during pregnancy shrink or disappear after pregnancy, as the uterus goes back to a normal size.

Fibroids range in size from seedlings, undetectable by the human eye, to bulky masses that can distort and enlarge the uterus. They can be single or multiple, in extreme cases expanding the uterus so much that it reaches the rib cage.

As many as 3 out of 4 women have uterine fibroids sometime during their lives, but most are unaware of them because they often cause no symptoms. Your doctor may discover fibroids incidentally during a pelvic exam or prenatal ultrasound.

Symptoms

In women who have symptoms, the most common symptoms of uterine fibroids include:

• Heavy menstrual bleeding
• Prolonged menstrual periods — seven days or more of menstrual bleeding
• Pelvic pressure or pain
• Frequent urination
• Difficulty emptying your bladder
• Constipation
• Backache or leg pains

Rarely, a fibroid can cause acute pain when it outgrows its blood supply. Deprived of nutrients, the fibroid begins to die. Byproducts from a degenerating fibroid can seep into surrounding tissue, causing pain and, rarely, fever. A fibroid that hangs by a stalk inside or outside the uterus (pedunculated fibroid) can trigger pain by twisting on its stalk and cutting off its blood supply.

Fibroid location, size and number influence signs and symptoms:

• Submucosal fibroids. Fibroids that grow into the inner cavity of the uterus (submucosal fibroids) are more likely to cause prolonged, heavy menstrual bleeding and are sometimes a problem for women attempting pregnancy.
• Subserosal fibroids. Fibroids that project to the outside of the uterus (subserosal fibroids) can sometimes press on your bladder, causing you to experience urinary symptoms. If fibroids bulge from the back of your uterus, they occasionally can press either on your rectum, causing a pressure sensation, or on your spinal nerves, causing backache.
• Intramural fibroids. Some fibroids grow within the muscular uterine wall (intramural fibroids). If large enough, they can distort the shape of the uterus and cause prolonged, heavy periods, as well as pain and pressure.

When to see a doctor

See your doctor if you have:

• Pelvic pain that doesn't go away
• Overly heavy or painful periods
• Spotting or bleeding between periods
• Pain consistently with intercourse
• Enlarged uterus and abdomen
• Difficulty emptying your bladder

Seek prompt medical care if you have severe vaginal bleeding or sharp pelvic pain that comes on suddenly.

Causes

Doctors don't know the cause of uterine fibroids, but research and clinical experience point to these factors:

• Genetic changes. Many fibroids contain changes in genes that differ from those in normal uterine muscle cells. There's also some evidence that fibroids run in families and that identical twins are more likely to both have fibroids than nonidentical twins.
• Hormones. Estrogen and progesterone, two hormones that stimulate development of the uterine lining during eachmenstrual cycle in preparation for pregnancy, appear to promote the growth of fibroids. Fibroids contain more estrogen and progesterone receptors than normal uterine muscle cells do. Fibroids tend to shrink after menopause due to a decrease in hormone production.
• Other growth factors. Substances that help the body maintain tissues, such as insulin-like growth factor, may affect fibroid growth.

Risk factors

There are few known risk factors for uterine fibroids, other than being a woman of reproductive age. Other factors that can have an impact on fibroid development include:

• Heredity. If your mother or sister had fibroids, you're at increased risk of developing them.
• Race. Black women are more likely to have fibroids than women of other racial groups. In addition, black women have fibroids at younger ages, and they're also likely to have more or larger fibroids.
• Other factors. Onset of menstruation at an early age, having a diet higher in red meat and lower in green vegetables and fruit, and drinking alcohol, including beer, appear to increase your risk of developing fibroids.

Complications

Although uterine fibroids usually aren't dangerous, they can cause discomfort and may lead to complications such as anemia from heavy blood loss.

Pregnancy and fibroids

Fibroids usually don't interfere with conception and pregnancy. However, it's possible that fibroids could cause infertility or pregnancy loss. Submucosal fibroids may prevent implantation and growth of an embryo. In such cases, doctors often recommend removing these fibroids before attempting pregnancy or if you've had multiple miscarriages. Rarely, fibroids can distort or block your fallopian tubes, or interfere with the passage of sperm from your cervix to your fallopian tubes.

Test and diagnosis

Uterine fibroids are frequently found incidentally during a routine pelvic exam. Your doctor may feel irregularities in the shape of your uterus, suggesting the presence of fibroids. If you have symptomsof uterine fibroids, you doctor may order these tests:

• Ultrasound. If confirmation is needed, your doctor may order an ultrasound. It uses sound waves to get a picture of your uterus to confirm the diagnosis and to map and measure fibroids. A doctor or technician moves the ultrasound device (transducer) over your abdomen (transabdominal) or places it inside your vagina (transvaginal) to get images of your uterus.
• Lab tests. If you're experiencing abnormal vaginal bleeding, your doctor may order other tests to investigate potentialcauses. These might include a complete blood count (CBC) to determine if you have anemia because of chronic blood loss and other blood tests to rule out bleeding disorders or thyroid problems.

Other imaging tests

If traditional ultrasound doesn't provide enough information, your doctor may order other imaging studies, such as:

• Magnetic resonance imaging (MRI). This imaging test can show the size and location of fibroids, identify different types of tumors and help determine appropriate treatment options.
• Hysterosonography. Hysterosonography (his-tur-o-suh-NOG-ruh-fee), also called a saline infusion sonogram, uses sterile saline to expand the uterine cavity, making it easier to get images of the uterine cavity and endometrium. This test may be useful if you have heavy menstrual bleeding despite normal results from traditional ultrasound.
• Hysterosalpingography. Hysterosalpingography (his-tur-o-sal-ping-GOG-ruh-fee) uses a dye to highlight the uterine cavity and fallopian tubes on X-ray images. Your doctor may recommend it if infertility is a concern. In addition to revealing fibroids, it can help your doctor determine if your fallopian tubes are open.
• Hysteroscopy. For this, your doctor inserts a small, lighted telescope called a hysteroscope through your cervix into your uterus. Your doctor then injects saline into your uterus, expanding the uterine cavity and allowing your doctor to examine the walls of your uterus and the openings of your fallopian tubes.

Prevention

Although researchers continue to study the causes of fibroid tumors, little scientific evidence is available on how to prevent them. Preventing uterine fibroids may not be possible, but only a small percentage of these tumors require treatment.