Fibroids are tumours that grow in the uterus (womb). They are benign, which means they are not cancerous, and are made up of muscle fibre. Fibroids can be as small as a pea and can grow as large as a melon. It is estimated that 20-50% of women have, or will have, fibroids at some time in their lives. They are rare in women under the age of 20, most common in women in their 30s and 40s, and tend to shrink after the menopause.

Causes of Fibroids

Inherited genetic factors may be important in many cases of fibroids. Researchers are investigating unique genetic factors that regulate hormones. Proteins called growth factors may be responsible for some of the abnormalities leading to uterine muscle overgrowth and fibroids. Scientists have identified chromosomes carrying a total of 145 genes that may affect fibroid growth. Some experts report that uterine fibroids are inherited from paternal (the father's) genes.

Signs and Symptoms

Heavy Vaginal Bleeding — Some women experience excessively heavy or prolonged menstrual bleeding. Not uncommonly, women describe soaking through sanitary protection in less than an hour, passing blood clots and being unable to leave the house during the heaviest day of flow. As a result of the blood loss, some women develop anemia, or a low blood count, which can cause fatigue or lightheadedness.

Fibroids can also cause a range of reproductive problems including recurrent miscarriage, infertility, premature labor, breech birth, and labor complications. Although research is scant in this area, some evidence indicates that those fibroids that alter the shape of the uterus are the most likely to cause these problems. Women who have large or symptomatic fibroids who wish to become pregnant could opt to have a diagnostic test to assess the uterine cavity.

When a woman develops abnormal bleeding, she notices that her menstural flow is heavier, but that it lasts—at least at first—for the same number of days. She frequently will find, however, that after a while her periods are lasting longer. Some women, in fact, bleed almost constantly. Excessive blood loss drains iron from a woman's body causing anemia.

At present, medications, a progesterone-releasing IUD, endometrial ablation, hysteroscopic myomectomy, laparoscopic myomectomy, abdominal myomectomy, uterine artery embolization and focused ultrasound are all available in addition to hysterectomy for treatment.

Very large fibroids may give the abdomen the appearance of pregnancy and cause a feeling of heaviness and pressure. In fact, large fibroids are defined by comparing the size of the uterus to the size it would be at specific months during gestation.

Treatment of Fibroids

There are not any currently available medicines that will permanently shrink fibroids. Often heavy bleeding can be decreased with birth control pills. There are a number of medications in the family of GnRH agonists, which induce a temporary chemical menopause. In the absence of estrogen myomas usually decrease in size. Unfortunately, the effect is temporary, and the fibroids rapidly go back to their pre-treatment size when the medication is discontinued. Mifepristone, better know as the 'French abortion pill, or RU-486, also may cause a decrease in size of myomas, and often stops abnormal uterine bleeding. It also has undesireable side effects. It's use is promising, but it is not currently available in the United States.

Hysterectomy is surgical removal of the uterus. This treatment may be used in women with severe uterine fibroids who do not wish to have children. Hysterectomy may also include removing other parts of the female reproductive system, such as the cervix, ovaries, and fallopian tubes. The procedure may be performed vaginally (called vaginal hysterectomy) or through an incision in the abdomen (called abdominal hysterectomy). Following hysterectomy, most patients remain hospitalized for 3 to 5 days. Recovery from the procedure usually takes about 6 weeks.