What is a fibroid?

Fibroids are benign nodules of muscle and other tissue that grow in the walls of the uterus. The medical term for a fibroid is a leiomyoma.

Fibroids are very common. Studies have estimated that up to 75% of women have at least one fibroid during their lifetime, although a majority of these are never diagnosed because they are often microscopic in size and do not lead to any symptoms.

Fibroids can grow in any direction, meaning they can grow only in the wall of the uterus, or they can grow on the outside of the uterus, or they can grow into the uterus. Fibroids vary from tiny nodules to large masses that weigh several pounds. Some fibroids grow quickly, while others grow very slowly.

Fibroids are benign growths and rarely, if ever, develop into cancer.

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What causes fibroids?

No one knows what causes fibroids, although the overwhelming majority occur in women of reproductive age, generally in the premenopausal period. Fibroids often grow rapidly during periods of high estrogen levels, such as during pregnancy, and tend to shrink with menopause.

Studies to find risk factors such as number of pregnancies and lifestyle factors (weight, smoking, etc.) have yielded conflicting results, although some studies found that women with fibroids tend to have higher blood pressure than women who don't develop fibroids.

There seems to be a genetic predisposition to fibroids, so that a woman with female first-degree relatives who have fibroids is more likely to develop fibroids herself.

Also, women of African ancestry are more prone to fibroids and tend to develop them at an earlier age than Caucasian women.

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What are the symptoms of a fibroid?

Most fibroids are silent; that is, they produce no symptoms, and either are never picked up or are diagnosed by a doctor doing a routine pelvic examination.

When fibroids produce symptoms, the most common are abnormal bleeding, such as excessive bleeding with menstruation, painful periods, bleeding between periods, and pain with intercourse. Large fibroids can produce a sense of fullness in the lower abdomen, and low back pain. Fibroids can also press on the bladder leading to symptoms such as frequent or painful urination.

Fibroids are also associated with infertility and recurrent miscarriages.

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How are fibroids diagnosed?

Most fibroids are picked up during routine pelvic examinations. The diagnosis is usually confirmed with an ultrasound examination and, if necessary, a hysteroscopy, a look into the uterus with a scope by way of the vagina, which also allows the doctor to take a biopsy of the tissue.

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How are fibroids treated?

Most fibroids can be left alone until menopause, when they tend to regress.

Pain can usually be treated with nonsteroidal anti-inflammatory medications such as ibuprofen.

The use of oral contraceptives (birth control pills) can often control excessive bleeding associated with fibroids, but is not known to slow the growth of fibroids.

GnRH agonists are other medications that are used to control fibroids, but they lead to many side effects and potential complications and should be reserved only for special cases. Ulipristal acetate, a drug that acts on progesterone receptors, is another option for women with moderate-to-severe signs and symptoms of fibroids.

Studies that involve the antiprogesterone drug RU-486 (the "abortion" pill) are currently being conducted to see if it can help fibroids regress.

Surgical choices for dealing with fibroids have improved greatly. The simplest surgical procedure that leads to temporary improvement in some symptoms, especially heavy bleeding, is a dilatation and curettage (a "D&C").

With many fibroids, it is now possible to remove only the fibroid and leave the rest of the uterus in place, and this can now be done with a minimally invasive procedure such as a laparoscopy or hysteroscopy.

For larger fibroids, the standard therapy has long been a hysterectomy, and these operations were often done for even minimal symptoms. Happily, however, the rate of hysterectomies has been decreasing in North America. Although hysterectomies are now reserved for only the most troublesome cases or when there is a worry that the fibroid may be hiding a uterine cancer, hysterectomies are still (after caesarean section) the second most common surgical procedure in women.

In a subtotal hysterectomy, only the uterus is removed, while the cervix, fallopian tubes, and ovaries, are left in place. Total hysterectomy involves removing the uterus and cervix, and most often the ovaries, too. This can be done through the vagina, or through the abdomen.

A procedure known as uterine fibroid embolization has been increasingly popular recently. In this procedure, a physician guides a long thin tube from a leg artery into the arteries in the uterus that also feed the fibroid. The blood flow in these arteries is then blocked with a gel, and when the blood flow to the fibroid is cut off, it shrinks. Most fibroids treated with embolization seem to eventually disappear altogether, although this is a relatively new procedure so there is not yet enough long-term data to know if those fibroids stay away.

Another therapy still being studied but showing promising results is the use of lasers to heat and shrink fibroids.

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Art Hister, MD 
with updates by the MediResource Clinical Team