Ultrasound is an imaging test that sends high-frequency sound waves through your breast and converts them into images on a viewing screen. The ultrasound technician places a sound-emitting probe on the breast to conduct the test. There is no radiation involved.
Ultrasound is not used on its own as a screening test for breast cancer. Rather, it is used to complement other screening tests. If an abnormality is seen on mammography or felt by physical exam, ultrasound is the best way to find out if the abnormality is solid (such as a benign fibroadenoma or cancer) or fluid-filled (such as a benign cyst). It cannot determine whether a solid lump is cancerous, nor can it detect calcifications.
If you’re under age 30, your doctor may recommend ultrasound before mammography to evaluate a palpable breast lump (a breast lump that can be felt through the skin). Mammograms can be difficult to interpret in young women because their breasts tend to be dense and full of milk glands. (Older women’s breasts tend to be more fatty and are easier to evaluate.) In mammograms, this glandular tissue looks dense and white — much like a cancerous tumor. Some doctors say that locating an abnormality in the midst of dense gland tissue can be like finding a polar bear in a snowstorm. Most breast lumps in young women are benign cysts, or clumps of normal glandular tissue.
Doctors also can use ultrasound to guide biopsy needles precisely to suspicious areas in the breast.