What Are Uterine Fibroids?

Uterine fibroids (also called uterine myomas, leiomyomas, or simply fibroids) are non-cancerous tumors that develop in the muscular wall of the uterus, which is found in the female pelvis between the bladder and the rectum. 

Fibroids can range in size (as small as a grape to larger than a melon) and are classified by their location, which affects the symptoms they cause and how they may be treated. They can develop:

  • Beneath the outer surface of the uterus
  • Totally within the wall of the uterus
  • Inside the uterine cavity

Risk Factors

Approximately 20-50 percent of women develop fibroids depending on race. The medical community is not certain what causes them or why some women develop them, but some factors that play a role include:

  • Age: middle-aged women are commonly diagnosed with fibroids
  • Weight: overweight women are at a higher risk for fibroids
  • Race: fibroids are more common in African-American women, although they are found in women of all ethnic backgrounds


Most fibroids do not cause symptoms, but some women may experience a combination of the following:

  • Heavy menstrual bleeding
  • Worsening pain with menstruation
  • Frequent urination, urgency to urinate, or rarely, the inability to urinate
  • Constipation
  • Pelvic pressure, "feeling full" in the lower abdomen
  • Lower abdominal pain
  • An increase in the size around one's waist and change in abdominal contour
  • Back ache or leg pain