Uterine leiomyomas (fibroids or myomas) are the most common pelvic tumor in women [1-3]. They are benign monoclonal tumors arising from the smooth muscle cells of the myometrium. They arise in reproductive age women and typically present with symptoms of heavy or prolonged menstrual bleeding or pelvic pain/pressure. Uterine fibroids may also have reproductive effects (eg, infertility, adverse pregnancy outcomes).
The epidemiology, clinical manifestations, diagnosis, and natural history of uterine leiomyomas are reviewed here. Treatment of uterine leiomyomas, leiomyoma histology and pathogenesis, differentiating leiomyomas from uterine sarcomas, and leiomyoma variants are discussed separately. (See "Overview of treatment of uterine leiomyomas (fibroids)" and "Histology and pathogenesis of uterine leiomyomas (fibroids)" and "Differentiating uterine leiomyomas (fibroids) from uterine sarcomas" and "Variants of uterine leiomyomas (fibroids)".)
TERMINOLOGY AND LOCATION
Fibroids are often described according to their location in the uterus, although many fibroids have more than one location designation (figure 1 and picture 1A-B). An International Federation of Gynecology and Obstetrics (FIGO) staging scheme for fibroid location has been proposed (figure 2) .
●Intramural myomas (FIGO type 3,4,5) – These leiomyomas develop from within the uterine wall. They may enlarge sufficiently to distort the uterine cavity or serosal surface. Some fibroids can be transmural and extend from the serosal to the mucosal surface.
●Submucosal myomas (FIGO type 0,1,2) – These leiomyomas derive from myometrial cells just below the endometrium. These neoplasms protrude into the uterine cavity. The extent of this protrusion is described by the FIGO/European Society of Hysteroscopy classification system and is clinically relevant for predicting outcomes of hysteroscopic myomectomy . A type 0 fibroid is completely intracavitary, type I has less than 50 percent of its volume in the uterine wall, whereas a type II has 50 percent or more of its volume in the uterine wall (figure 3). Types 0 and I are hysteroscopically resectable, although significant hysteroscopic expertise may be needed to resect type I masses. (See "Hysteroscopic myomectomy", section on 'Myometrial penetration'.)