An ultrasound uses sound-waves to build up a picture of the breast tissue. It can show if a lump is solid (made of cells) or if it is a fluid-filled cyst. It can also show whether a solid lump is regular or irregular in shape.
You will be asked to remove the clothes from the top half of your body. Then you lie down on a couch with your arm above your head. The person doing the scan puts a gel onto your breast tissue. They move a small device over the area. A picture of the breast tissue shows up on a screen. An ultrasound only takes a few minutes and is painless.