Uterine fibroids are formed by the proliferation of smooth muscle cells in the uterus. According to the growth site, they are classified as uterine fibroids, cervical fibroids and broad ligament fibroids; according to the relationship between fibroids and the uterine muscle wall, they are classified as intermyometrial fibroids, subplasmic fibroids and submucosal fibroids. Interstitial fibroids are fibroids located between the myometrial walls of the uterus; subplasma fibroids are fibroids that grow toward the plasma membrane of the uterus and protrude from the surface of the uterus; submucosal fibroids are fibroids that grow toward the uterine cavity and protrude from the uterine cavity. Most fibroids are benign, but if they grow rapidly and increase in size in a short period of time, one should be highly alert to the risk of malignant transformation.