Biopsy is defined as small amount of tissue removed from the breast to be studied under the microscope. An ultrasound biopsy will require you to lie on your back with your arm on the biopsy side above your head. They will use ultrasound to identify the target area. During your biopsy you need to lie very still since you will feel pressure and possibly mild pain, and if you feel severe or sharp pain let your doctor know. They will then use ultrasound to guide the biopsy needle into target area and take approximately five samples.