Procedure Ultrasound Core Biopsy is a minimally invasive procedure that allows the radiologist to obtain tissue cores of masses for pathologic evaluation. In many instances, breast abnormalities can be seen both on mammogram and ultrasound. In these cases, ultrasound core biopsy is chosen for patient comfort. The patient lies comfortably on an examining table. The abnormality is identified using ultrasound. The skin is prepped with betadyne. Local anesthetic is placed in the skin and subcutaneous tissues. A coaxial core biopsy needle is placed to obtain multiple samples. A coaxial, or two needle system, allows the first needle to be placed through the skin and adjacent to the area of interest. The first needle acts as a guide or tunnel through which a smaller core biopsy needle is placed to obtain multiple samples. No skin incision is required. If the final results are benign, surgery is usually not necessary and patients can be followed conservatively.