With a sonogram they will be looking if the lump is fluid filled or solid they may also be checking if there are any other suspicious areas. There are different types of biopsies. Fine needle aspirate they insert a wide bore needle and aspirate some of the tissue and send it to the lab. A cone knive biopsy they remove a cone shape tissue sample and send that for pathology and then there is a wide incisional biopsy that they remove the entire lump or suspicious area pathology is able to evaluate the whole area and the surgeon can check for clean margins. The surgeon will usually decide what type of biopsy will give the best diagnosis.