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What Are Uterine Fibroids?

The uterus is a muscular, hollow, pear-shaped organ located in the pelvic cavity behind the bladder and in front of the rectum. The lower portion narrows into the cervical opening, which leads to the vagina. The fallopian tubes are attached on either side of the upper portion of the uterus. The uterus is lined with a mucous membrane called the endometrium, whose state changes with the phases of the menstrual cycle. During normal reproduction, a fertilized egg implants itself in the wall of the uterus. It is here that the embryo develops into the fetus, which grows and is nourished until birth.

Fibroids are benign tumors, or growths of the muscles and fibrous tissue of the uterus. Fibroids vary in size, 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 about 20-50% of women of reproductive age. For unknown reasons, fibroids are more common in black women.

Although they are usually not problematic, fibroids may cause enlargement and distortion of the uterus and make it difficult to become pregnant. Sometimes a fibroid attached to the uterine wall becomes twisted or outgrows its blood supply, causing it to be starved for blood and oxygen. When this happens, you may suddenly feel a sharp pain in your abdomen. The pain can be crampy in nature and feel similar to a miscarriage, since the uterus muscle may be trying to "rid" itself of the "mass" in its center. See your physician without delay to have this fibroid tumor removed.

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 red blood cell count). Often, however, there are no symptoms at all. Because fibroids are affected by hormones, 20% enlarge during pregnancy. Complications of pregnancy and fibroids include miscarriage, going into labor early(15-20%), abdominal pain, abruption of the placenta (the placenta detaching), poor growth of the baby (10%), bleeding after delivery or the baby not being head first (20%).

Fibroids usually shrink after menopause.

Fibroids are thought to develop due to genetic mutations and their growth is related to hormones. Because of this, oral contraceptives, estrogen replacement therapy and pregnancy may cause fibroids to grow and expand.