Uterine fibroids are benign tumors of the smooth muscle cells that normally form the wall of the uterus. These are also sometimes called uterine leiomyomas, myomas, or fibromyomas. Approximately twenty five percent (25% or 1 in 4) of reproductive age women have clinical evidence of a fibroid uterus (for example, enlarged uterus on pelvic examination or ultrasound findings consistent with fibroids), which makes uterine fibroids the most common tumors of the female pelvis.
The location and size of fibroids within the uterus are important since location (and to a lesser extent size) predicts the type and severity of problems that they cause. The majority of fibroids cause no significant clinical problems but 25-35% may cause excessive uterine bleeding, fertility problems or pain.
A subserosal myoma is located immediately under the serosa or outer covering of the uterus and these subserosal myomas generally project into the abdomen, may become very large, and often degenerate when they outgrow their blood supply to produce pain. Most often, fibroids cause pressure or a feeling of persistent fullness when they become large rather than pain. Large myomas can also push on surrounding structures to cause urinary frequency without pain or burning or changes in the usual pattern of bowel movements (often constipation).
A submucosal myoma is located immediately below the endometrial lining of the cavity inside the uterus and submucosal myomas generally project into the uterine cavity, may disrupt the endometrial lining that must grow around the developing fibroid, and often produce reproductive problems for the woman (such as heavy uterine bleeding, spontaneous pregnancy loss, or reduced fertility). It is difficult to assess excessive uterine bleeding and signs of a bleeding abnormality include a recent noticeable increase in the amount of flow or bleeding through protection. When fibroids grow into the uterine cavity they can result in a hostile environment for embryo development and they can cause miscarriages or reduced fertility.
An intramural myoma is located within the uterine wall where these intramural myomas can replace (or displace) large sections of the normal uterine wall and are often asymptomatic (cause no clinical problems). Intramural or transmural myomas do not usually need to be removed or treated. Some recent research suggests that very large intramural myomas may reduce embryo implantation rates, but more information is needed on this subject to guide clinical management.
Simply treating their symptoms treats most fibroids.
Chronic pelvic pain due to fibroids is uncommon, so initially treating other concurrent pelvic pathology like endometriosis or pelvic adhesions is reasonable. The treatment of chronic pelvic pain in women with fibroids must be individualized. If other identified problems have been treated and the only cause for pain is thought to be a degenerating fibroid, then removal of the fibroid should be considered. If fertility is not desired, a hysterectomy (removal of the entire uterus including fibroids) or uterine artery embolization may be considered. Uterine artery embolization (UAE) involves the insertion of a small catheter into a large blood vessel, threading the catheter through the circulatory system to a vessel feeding the fibroid, and inserting tiny particles that clot the blood in the vessel to arrest blood flow to the myoma. This usually causes the fibroid to rapidly decrease in size within a few days to weeks, but these rapid changes can also cause additional significant pain.
Heavy uterine bleeding may result in anemia (a reduced red blood cell count). The red blood cell count is often effectively restored with iron supplementation but if there is a persistent problem, then removal of the submucosal myoma (generally performed by hysteroscopy), endometrial ablation (a procedure that destroys the endometrial lining cells of the uterine cavity with heat), or myolysis (thermal coagulation or cryoablation of the fibroid) can be considered.