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Symptoms and Signs of Uterine Fibroids

Doctor's Notes on Uterine Fibroids

Uterine fibroids are benign (non-cancerous) tumors of smooth muscle that originate in a woman’s uterus (womb). The medical terms for a fibroid is leiomyoma. The cause of fibroids is not well understood, but they are very common in women of childbearing age.

Fibroids range dramatically in size. They may be microscopic or may be eight or more inches across. Typically they are between the size of a marble and a baseball. Fibroids may occur in clusters. In most cases, fibroids do not have any associated symptoms. However, depending on their size, location within the uterus, and proximity to other pelvic organs, they may cause abnormal vaginal bleeding or heavy menstrual periods, abdominal or pelvic discomfort, frequent urination, or a feeling of pressure in the lower abdomen.

Medical Author:
Medically Reviewed on 3/11/2019

Uterine Fibroids Symptoms

Most fibroids, even large ones, produce no symptoms. These masses are often found during a regular pelvic examination.

When women do experience symptoms, the most common are the following:

  • an increase in menstrual bleeding, known as menorrhagia, sometimes with blood clots;
  • pressure on the bladder, which may cause frequent urination and a sense of urgency to urinate and, rarely, the inability to urinate;
  • pressure on the rectum, resulting in constipation;
  • pelvic pressure, "feeling full" in the lower abdomen, lower abdominal pain;
  • increase in size around the waist and change in abdominal contour (some women may need to increase their clothing size but not because of a significant weight gain);
  • infertility, which is defined as an inability to become pregnant after 1 year of attempting to get pregnant; and/or
  • a pelvic mass discovered by a health care practitioner during a physical examination.

Uterine Fibroids Causes

The exact reasons why some women develop fibroids are unknown. Fibroids tend to run in families, and affected women often have a family history of fibroids. Women of African descent are two to three times more likely to develop fibroids than women of other races.

Fibroids grow in response to stimulation by the hormone estrogen, produced naturally in the body. These growths can show up as early as age 20, but tend to shrink after menopause when the body stops producing large amounts of estrogen.

Fibroids can be tiny and cause no problems, or they also can grow to weigh several pounds. Fibroids generally tend to grow slowly.

The following factors have been associated with the presence of fibroids:

  • Being overweight, obesity
  • Never having given birth to a child (called nulliparity)
  • Onset of the menstrual period prior to age 10
  • African American heritage (occurring 3-9 times more often than in Caucasian women)

What Are Uterine Fibroids? Symptoms, Treatment, Pictures Slideshow

What Are Uterine Fibroids? Symptoms, Treatment, Pictures Slideshow

Uterine fibroids are noncancerous tumors that grow along or within the walls of the uterus. They are primarily made up of smooth muscle cells, along with small amounts of other tissues. They range dramatically in size. Some fibroids are microscopic, whereas others may be eight or more inches across. On average, these tumors range from about the size of a large marble to a bit smaller than a baseball.

Sometimes fibroids are found alone, and other times they grow in clusters. Many of them grow, but others shrink or remain the same size as time passes.

To understand this most common noncancerous tumor in women of childbearing age, read along as we provide medically-reviewed information about symptoms, treatments, and pictures. Along the way you will learn sometimes surprising facts about these growths, arming yourself with useful information.


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.