Uterine Fibroids

Uterine fibroids are common, non-cancerous growths that develop in the uterus, often appearing during the reproductive years when you are typically able to conceive and give birth. These fibroids, also known as leiomyomas (lie-o-my-O-muhs) or myomas, almost never turn into cancer and are not associated with an increased risk of other types of cancer in the uterus.

Fibroids vary in both number and size; you can have a single fibroid or multiple. Some fibroids are so small that they are not visible to the naked eye, while others can grow as large as a grapefruit or even larger. When a fibroid becomes very large, it can distort the shape of the uterus both inside and out. In extreme cases, some fibroids grow large enough to fill the pelvis or abdominal area, giving the appearance of pregnancy.

Many women develop uterine fibroids at some point in their lives, but you might not be aware of them since they often cause no symptoms. Fibroids are frequently discovered incidentally during a pelvic exam or a pregnancy ultrasound conducted by your healthcare professional.

Causes of Uterine Fibroids

The exact cause of uterine fibroids isn’t fully understood, but several factors may contribute to their development:

Gene Changes: Many fibroids contain genetic alterations that differ from those in normal uterine muscle cells.
Hormones: Estrogen and progesterone, two hormones that cause the uterine lining to thicken during each menstrual cycle in preparation for pregnancy, also appear to promote the growth of fibroids. Fibroids contain more cells that bind to estrogen and progesterone than typical uterine muscle cells. After menopause, when hormone levels drop, fibroids often shrink.
Other Growth Factors: Substances that help maintain tissues, such as insulin-like growth factor, may influence fibroid growth.
Extracellular Matrix (ECM): ECM is a material that helps cells stick together, similar to mortar between bricks. Increased ECM in fibroids makes them more fibrous and also stores growth factors, causing biological changes in the cells themselves.

Doctors believe that uterine fibroids may originate from a stem cell in the smooth muscle tissue of the uterus. This single cell repeatedly divides, eventually forming a firm, rubbery mass that is distinct from the surrounding tissue.

The growth patterns of uterine fibroids can vary significantly. They may grow slowly or rapidly, or they might remain the same size. Some fibroids experience growth spurts, while others may shrink on their own.

Fibroids that develop during pregnancy may shrink or disappear after childbirth as the uterus returns to its normal size.

Uterine Fibroids Symptoms

Many women with uterine fibroids experience no symptoms. For those who do, the symptoms can vary depending on the location, size, and number of fibroids.

The most common symptoms of uterine fibroids include:

Heavy menstrual bleeding or painful periods.
Longer or more frequent periods.
Pelvic pressure or pain.
Frequent urination or trouble urinating.
Growing stomach area.
Constipation.
Pain in the stomach area or lower back, or pain during sex.

Rarely, a fibroid can cause sudden, serious pain when it outgrows its blood supply and starts to die.

Often, fibroids are grouped by their location. Intramural fibroids grow within the muscular wall of the uterus. Submucosal fibroids bulge into the uterine cavity. Subserosal fibroids form on the outside of the uterus.

When to see a doctor

See your doctor if you have:

Pelvic pain that doesn't go away.
Heavy or painful periods that limit what you can do.
Spotting or bleeding between periods.
Trouble emptying your bladder.
Ongoing tiredness and weakness, which can be symptoms of anemia, meaning a low level of red blood cells.

Get medical care right away if you have severe bleeding from the vagina or sharp pelvic pain that comes on fast.