Breast ultrasound is a procedure that may be used to determine whether a lump is a cyst (sac containing fluid) or a solid mass which might be cancer. If the lump is found to be a cyst, fluid is typically withdrawn from it using a needle and syringe (a process called aspiration). If clear fluid is removed and the mass completely disappears, no further treatment or evaluation is needed.
Ultrasound can also be used to precisely locate the position of a known tumor to help guide the doctor during a biopsy or aspiration procedure. Ultrasound helps confirm correct needle placement.
Ultrasound testing works by transmitting high-frequency sound waves, inaudible to the human ear, through the breast. The sound waves bounce off surfaces in the breast (tissue, air, fluid) and these "echoes" are recorded and transformed into video or photographic images.