About Uterine Fibroids

Uterine Fibroid diagram
A diagram showing various types of uterine fibroids.

Fibroids, also called leiomyomas, are benign (non-cancerous) uterine tumors. They are made up of normal uterine muscle cells, growing in a round ball. A good comparison is moles on the skin, which are also made up of normal tissue growing in abnormal clumps. Fibroids can grow within the uterine wall ("mural"), on the outside of the uterus ("serosal"), or inside the uterine cavity ("submucosal"). They can even grow on a mushroom-like stalk ("pedunculated"). Fibroids don’t generally cause problems unless they grow to a significant size or are in a sensitive location in the uterus.

Fibroids are vascular tumors. That means they have a rich supply of blood vessels, most often coming from the uterine artery. A woman might have one or many fibroids, and those could be in many locations. Fibroids can range in size from a few millimeters (the size of a pea) to 40 centimeters (the size of a full-term baby).

Fibroids are responsive to hormonal stimulation, and may grow steadily during the fertile period of a woman's life. They frequently begin to shrink after menopause.

Pedunculated fibroids can sometimes lose their blood supply spontaneously, by twisting around on the stalk. When this happens, the fibroid will usually begin to shrink. The uterine fibroid embolization (UFE), which is also known as uterine artery embolization or UAE, procedure duplicates this naturally occurring process.

How common are fibroids?

Fibroids occur in 25-30% of women, and are slightly more common among African-Americans. Only about half the women with fibroids develop symptoms. However, fibroids are the cause of about a third of the hysterectomies performed in the United States every year.

What symptoms do fibroids cause?

The most common symptoms are pelvic pressure, pain during sex, excessive vaginal bleeding and a feeling of abdominal or pelvic fullness. In addition, the weight of a fibroid can compress the rectum and urinary bladder, causing constipation or frequent urination.

Not every woman with these symptoms has fibroids. There can be other causes for vaginal bleeding, pelvic pain and pain during sex. Some of these conditions can be serious and require treatment. Each woman must be completely evaluated by a provider with experience and training in women's health.

Do fibroids cause infertility?

The answer is a bit complicated. Pregnancy is defined as the implantation (attachment) of a fertilized egg to the uterine wall. Fibroids do not prevent fertilization, but they can prevent the fertilized egg from attaching to the uterine wall, or prevent the uterine cavity from expanding normally to accommodate the growing fetus. In other words, fibroids do not prevent pregnancy, but they can cause pregnancy to not be successful. Some treatments can help preserve fertility, so if pregnancy is a goal, be sure to tell your doctors.

Do fibroids have to be treated?

It is important to remember that fibroids are benign and non-cancerous, and cause symptoms in only about half of the women who have them. Asymptomatic fibroids do not require treatment.

Even if there are mild symptoms, a woman may not want treatment. However, when symptoms begin to have a negative impact on a woman's quality of life, then the fibroids should be treated.