What to Expect If You're Having a Breast Ultrasound Test

Ultrasound may be your next step if you and your doctor have confirmed that there's some sort of unexplained lump in your breast. Maybe you can't feel it, but it shows up on your mammogram. Or maybe your mammogram looks normal, but you (or your doctor) know it's there. "I started calling it Lumpy," says Kim Heier, 42, of Simi Valley, Calif., about the mysterious form in her breast. "It seemed to help."

Many lumps turn out to be cysts—harmless sacs of fluid. "Almost all [cysts] are benign," notes Peter M. Jokich, MD, director of the Rush Breast Imaging Center at Rush University Medical Center in Chicago. But to know for sure, you may be sent for an ultrasound to see if the radiologist can get more information than a mammogram can show.

Ultrasounds bounce pain-free sound waves off your breast tissue. You lie back while a doctor or technician drags a handheld device across the surface of your breasts and watches the resulting pictures on a nearby monitor.

Also called sonograms, ultrasounds are great for spotting whether a lump is solid or fluid. They are not as good, however, as mammograms at identifying microcalcifications—tiny calcium deposits that can indicate cancer when clustered together.

If your lump is solid, there's a chance it could be cancer, and you're on to the next test, which may be an MRI or a biopsy.