About one-third of all women have uterine fibroids, non-cancerous growths inside the uterus. When they make themselves known, the symptoms can be frightening. These include intense pain and excessive menstrual bleeding. In the worst cases, a trip to the emergency room may be required.

However, most fibroids don't cause any problem. In fact, their existence may not even be suspected.

The number, size and location of fibroids determines whether they are a cause for concern, said three obstetrician/gynecologists with expertise in fibroids.

"They tend to vary in size, from a few centimeters to as large as a watermelon," said Sridhar Iyer, an ob/gyn at the Encinitas Women and Children's Health Center.

The heavy bleeding in some fibroids is not only disconcerting, it can cause anemia.

Fibroid growth appears to be promoted by the female hormones estrogen and progesterone, Iyer said. That means they grow most rapidly in the young, and slow or stop growth after menopause.

Besides excess bleeding or pain, fibroids can sometimes announce their presence as a feeling of heaviness in the pelvis, caused by the distended uterus.

If fibroids are discovered during a routine exam and aren't causing any problems, most doctors will recommend nothing more than observation, said Dr. David Priver, an ob/gyn in San Diego and a former president of the San Diego County Medical Society. If a follow-up exam shows the fibroids are not growing, they can just be left in place. But if they are growing rapidly, the fibroids should be removed.

Hysterectomy -- removal of the uterus -- is the most popular way of getting rid of fibroids. It is often considered essential with the most troublesome fibroids, which grow clear through the uterine lining.

But other, less drastic measures also have been developed to remove or reduce fibroids, important for women who hope to bear children. These include myomectomy, removal of just the fibroids; embolization, or blocking the fibroids' blood supply; and reduction by ultrasound, coagulation or freezing of the fibroids.

"Fibroids are the biggest reason for hysterectomies in the United States, and probably the world," Priver said. "There's a huge debate raging: is it really necessary to do this?"

Treatments

The heavy-bleeding fibroids can sometimes be controlled with hormone therapy, said Dr. Nerissa Safie, an ob/gyn who practices in Southwest Riverside County with Southwest Healthcare System. The drug Lupron, which suppresses the menstrual cycle, can stop fibroid bleeding and actually shrink the fibroids. But once the therapy is discontinued, the growth and bleeding usually resume.

"It can be useful for women who are close to menopause," Safie said. Lupron also can be used before surgical removal of the fibroids to shrink them, making the operation less difficult.

Embolization, the newest technique, blocks the main blood vessels feeding the fibroids. A catheter is inserted into the femoral artery of the leg, and guided with X-ray imaging into the uterus to the fibroid arteries. Small particles of polyvinal alcohol are then injected, and wedge themselves into the arteries. With the blood supply reduced, the fibroids don't get the nutrients they need to grow.

This procedure works about 80 percent of the time, Safie said, and some women of childbearing age have had babies after embolization.

Fibroids can interfere with fertility and increase the risk of premature deliveries, Iyer said. Thus, fibroids are sometimes removed for this reason when a woman can't get pregnant.

"We generally try to rule out all other causes of infertility first," Iyer said.

New treatments are being studied. In May, researchers at the University of Pennsylvania School of Medicine announced that they were testing what they hope is a more effective method of embolization. The clinical trial, conducted at the university, will compare two different embolization particles.

And in November, a report on ultrasound therapy found it significantly relieved fibroid symptoms. The report was presented at the annual meeting of the Radiological Society of North America by a team led by Fiona M. Fennessy, an instructor of radiology at Harvard Medical School and a staff radiologist at Brigham and Women's Hospital in Boston.

The ultrasound treatment works like embolization in that it stops blood flow to the fibroids, starving them. The ultrasound, focused precisely on the fibroids, heats them up, cutting off the blood supply. The affected tissue dies. No serious bad effects were reported, and the benefits continued in follow-up exams conducted two and three years after treatment.

Causes

Why do fibroids form?

"We really don't know, other than to say there's a hereditary connection," Priver said. Women who have fibroids tend to have daughters with fibroids. They are also more prevalent among black women. Up to half of black females have fibroids, according to the National Institutes of Health.

Fibroids arise from a uterine muscle cell that begins to proliferate, producing a mass of tissue that grows beyond the normal confines of the uterus. They can grow on the exterior wall of the uterus, inside the uterine wall, or the uterine interior, Priver said. Interior fibroids enlarge the surface area of the uterus, which is directly related to the amount of menstrual flow.

The ones that grow right inside the wall are often the most troublesome.

"Oftentimes it acts as a foreign body, and the muscles in the uterus try to expel it," which causes painful cramps, Priver said.

Unlike cancers, these benign tumors don't spread to other parts of the body; they just grow in place. However, even tumors that grow in place can be troublesome, Priver said. They can enlarge the uterus so it presses on other organs such as the bladder.

But for all the complications fibroids can cause, the odds of them posing a serious health threat are quite low.

"Fibroids fall into one of two categories: dangerous vs. nuisance," Priver said. "With very few exceptions, they fall into the nuisance category."

Contact staff writer Bradley J. Fikes at (760) 739-6641 or bfikes@nctimes.com.

More about uterine fibroids

Clinical trial: ablation therapy.

Subjects are pre- or peri-menopausal women who wish an alternative to hysterectomy. Patients must not be seeking fertility treatment and should have a uterine size equal to less than 24 weeks pregnancy. Held at UC San Diego. Contact: Gabriella Iussich, (619) 471-9525.

United States National Women's Health Center site on Uterine Fibroids

http://www.4woman.gov/faq/fibroids.htm

Mayo Clinic

http://www.mayoclinic.com/health/uterine-fibroids/DS00078

National Uterine Fibroids Foundation

http://www.nuff.org