Understanding Uterine Fibroids -- the Basics
What Are Uterine Fibroids?
The uterus is a muscular, hollow, pear-shaped organ in the pelvis. It is positioned behind the bladder and in front of the rectum. The lower portion narrows into the cervix, which opens to the vagina.
Fibroids are benign (noncancerous) tumors, or growths of the muscle and connective tissue of the uterus. They usually grow slowly and may occur inside the uterine cavity, within the uterine wall, or on the outside surface of the uterus. They occur in 20% to 50% of women of reproductive age. For unknown reasons, fibroids are more common in African-American women.
Women with fibroids may experience uterine pain and abnormal bleeding -- usually heavy, prolonged periods, especially if the fibroid is within or next to the uterine cavity. Many women with smaller fibroids have no symptoms at all, and the fibroids may be identified coincidentally.
During normal reproduction, a fertilized egg implants itself in the wall of the uterus. It is here that the embryo develops and grows into a fetus, and where the fetus is nourished until birth.
Uterine fibroids may cause enlargement and distortion of the uterus and make it difficult to become pregnant. Fibroids are identified as the sole cause of infertility in less than 10% of the time, but fibroids that distort the uterine lining have been found to contribute to recurrent miscarriages.
Sometimes, a fibroid attached to the uterine wall becomes twisted or outgrows its blood supply, leaving it starved for blood and oxygen. If this happens, you may suddenly feel a sharp pain in your abdomen. This pain can feel crampy in nature, similar to labor pains, because the uterus may be contracting.
Fibroids may cause bladder or bowel pressure, or make intercourse painful for you. If they cause your period to become excessively heavy, you could develop anemia (low levels of red blood cells in your blood). Often, however, there are no symptoms at all.
Because fibroids are affected by hormones, 20% of fibroids enlarge during pregnancy. Complications of having fibroids during pregnancy include:
- Early labor
- The baby is not positioned ''head down'' for birth
- The fetus grows poorly
- Placenta abruption (the placenta detaches from the uterine wall)
- Bleeding in the mother after delivery
- Miscarriage
Fibroids usually shrink after menopause.
Fibroids are thought to develop due to genetic mutations. Their growth is related to hormones; birth control pills, estrogen replacement therapy, and pregnancy may cause fibroids to grow and expand.
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