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  • Women's Health: Uterine Fibroids What Are Uterine Fibroids?

  • Women's Health: Uterine Fibroids
    What Are Uterine Fibroids?

    Fibroids are benign (non-cancerous) growths that originate from the wall of a woman's uterus. Other names for fibroids include leiomyoma (lie-o-my-o-ma), myoma, or fibromyoma. These growths, or tumors, vary widely in size and shape. They may be as small as a chestnut or as large as a cantaloupe. Fibroids can even be large enough to cause a woman's uterus to expand to the size it would be at 4 to 5 months of pregnancy. Fibroids are extremely vascular, which means that they have a great deal of blood flowing to them. Without this blood flow a fibroid cannot survive.

    The uterus has multiple layers. These layers are depicted in figure 1. Fibroids originate from the myometrium (my-o-me-tree-um) and grow to involve the different uterine layers. The exact location of a fibroid is an important determinant of the symptoms it may produce. Location will also help determine the appropriate treatment for symptomatic fibroids. Fibroids are assigned names based on layer of the uterus that they primarily involve:

    • Intramural fibroids are within the middle layer of the uterine wall. This is the most common location for fibroids. Fibroids in this location most often produce low-back or pelvic pain. These fibroids may also contribute to heavy menstrual bleeding.

    • Submucosal (sub-mew-ko-sal) fibroids are located just beneath the inner lining of the uterus. This inner lining is called the endometrium (end-o-me-tree-um). The endometrium is the most active layer during a woman's monthly hormonal cycle. This layer increases in thickness until the end of the cycle when this tissue is shed during a woman's period. Given these facts, it is not surprising that fibroids in this layer often produce bleeding problems. The endometrium is also very important in achieving pregnancy. This layer is where a fertilized egg should implant itself following conception. When a submucosal fibroid protrudes into the uterine cavity, it can make it difficult for a woman to get pregnant.

    • Subserosal fibroids are located just beneath the outer lining of the uterus, or serosa (sir-o-sa). They produce an irregular uterine surface but generally do not cause bleeding. Fibroids in this location most often produce pelvic pain or fullness.

    Fibroid Q&A: Causes, Diagnosis and Treatment

    Information in this section is provided by Rhode Island Hospital's department of radiology, which offers a complete range of diagnostic and interventional procedures for women, including uterine artery embolization, a leading treatment for fibroid tumors.

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