A breast ultrasound uses sound waves to make a picture of the breast. A breast ultrasound can show all areas of the breast, including the area close to the chest wall.

A breast ultrasound is most often used to check a breast lump found on breast self-examination, physical examination, or on a mammogram. An ultrasound can tell if a breast lump is filled with fluid (a cyst) or is solid. A lump that has no fluid or that has fluid with floating particles may need more tests.

A breast ultrasound does not cause pain. A small handheld unit called a transducer is gently passed over the breast. A computer converts the sound waves into a picture that is shown on a TV screen. The picture is called a sonogram or ultrasound scan.

Breast ultrasound does not use X-rays or other potentially harmful types of radiation.