About Fibroids

What are the female reproductive organs?

Front View of Pelvis

Front view of pelvis - click to enlarge

The female reproductive system consists of the uterus, ovaries, fallopian tubes, cervix and vagina.The structures are located in the pelvis.The uterus (womb) is a pear-shaped organ located between the bladder and the rectum. The uterine walls are composed of muscle which allows it to expand enormously during pregnancy. Within the uterus is a central cavity in which the fetus (baby) develops. No hormones are produced by the uterus.The endometrium is the inner lining of the uterine cavity. A menstrual period results from the sloughing off of the endometrium. Fibroids located beneath this lining can cause very heavy bleeding.The ovaries are tethered to the upper aspect of the uterus, in close proximity to the ends of the fallopian tubes. The female hormones, estrogen and progesterone, are made by the ovaries. The fallopian tubes are located at each side of the uterus. Fertilization of the egg (ovum) occurs within the fallopian tube.

Side View of Pelvis

Side view of pelvis - click to enlarge

The cervix is the lowest part of the uterus. It has a narrow canal through which menstrual blood passes. The main function of the cervix is to hold the uterus closed during pregnancy. In a sub-total, partial or supracervical hysterectomy, the cervix is left in place.The vagina is the tubular structure between the external genitalia and the cervix.

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Uterine Fibroids

Uterine fibroids - click to enlarge

What are fibroids?
Fibroids are round muscle growths that develop within the uterus (womb). Fibroids are almost always benign (non-cancerous). Fibroids range in size from as small as a pea to as large as a melon. They are also called leiomyomas or myomas.

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What are the different types of fibroids?

Fibroids can grow in different parts of the uterus. Pedunculated fibroids are attached to the uterine wall by stalks. Subserosal fibroids extend outward from the uterine wall. Submucosal fibroids expand from the uterine wall into the uterine cavity. Intramural fibroids develop within the uterine wall. Different types of fibroids are associated with different symptoms. For example, submucosal fibroids typically cause heavy periods. In contrast, subserosal fibroids are more likely to push against the bladder causing frequent urination.

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What causes fibroids?
Physicians and medical researchers do not know what causes fibroids to develop. There is evidence that the female hormones, estrogen and progesterone, can make them grow. During pregnancy, when the hormone levels are high, fibroids tend to increase in size. After menopause, when the hormone levels are low, fibroids stop growing and may become smaller.

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Who is affected by fibroids?
Fibroids are very common. It is estimated that 20-50% of all women have these benign uterine growths. Fibroids are most likely to affect women in their 30's and 40's. For reasons we don't understand, fibroids occur more frequently in African-American women. Many women with fibroids have other family members with fibroids too.

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What happens to fibroids over time?
Some fibroids grow steadily during the reproductive years and some stay the same size for many years. All fibroids should stop growing after menopause. Women with fibroids that enlarge after menopause, should seek evaluation from their doctor.

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When is fibroid treatment necessary?
Most fibroids, even large ones, do not produce symptoms. Unless a woman is experiencing symptoms, she usually doesn't need to undergo a fibroid treatment. However, when fibroids cause symptoms, a woman should seek medical attention.

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What happens next?
No two women with fibroids are alike. The type of treatment will depend on the severity of the symptoms and the fibroid size, number and location. Your preference and desire for future childbearing also enters into the treatment discussion. There are many effective ways to treat fibroids. Not all treatments are recommended for all women. For example, some fibroid treatments may not be proven safe for women desiring future childbearing.

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UCSF Comprehensive Fibroid Center