What are uterine fibroids?

Uterine fibroids are tumors, which grow from cells forming the muscle of the uterus (womb). Uterine fibroids, which are also called leiomyoma or myoma of the uterus, can grow on the uterine wall and push out into the bladder, bowel or intestine. They can also grow within the uterine wall, or even project from the wall of the uterus on a narrow stalk into the uterine cavity.

Fibroids can be as small as a pea or as large as a football and are almost always benign, no matter how large they get. Having uterine fibroids does not increase your risk of cancer.

If a fibroid or cluster of fibroids is particularly large or is growing on the outside of the uterine wall, it can sometimes push the uterus aside or force it to grow abnormally. A uterine growth may also put pressure on the bladder or intestines.

On rare occasions, a large fibroid may block the opening of the uterus. In that case, a pregnant woman may need to have a caesarean delivery.
 
Why do women get them?

No one is certain what causes uterine fibroids, but changing estrogen levels seem to play a part in their growth. When estrogen levels are high, as a result of pregnancy or contraceptive pills, for example, the rate of fibroid growth increases. 

About 20 per cent of women of childbearing age have uterine fibroids but they are not usually found in women under 30 years old. They rarely appear in young women before they begin menstruating. 

As a woman approaches the menopause and her estrogen levels decrease, uterine fibroids are likely to shrink or almost disappear. Apart from being a woman of reproductive age, no other risk factors for fibroids have been found.
 

What are the symptoms?

Many women never even know they have uterine fibroids. If symptoms do exist, they may include:

  • painful periods
  • prolonged and heavy menstrual bleeding (which may lead to iron deficiency or anemia)
  • more frequent or uncomfortable urination caused by pressure on the bladder
  • feeling of fullness or pressure in the lower abdomen
  • pelvic pain
  • backache
  • constipation
  • infertility
  • miscarriage