Women who have symptoms, such as a dominant lump, mass or lesion, or a clear or bloody nipple discharge, should be scheduled for a diagnostic mammogram. Others who may need this exam include women who have had breast cancer, a recent biopsy or a recent mammographic abnormality. 
A diagnostic mammogram consists of at least four images - two pictures of each breast, one from the top-to-bottom and one from the side. Special consideration is taken at the area of concern, which is usually marked.
A signed order from a health care provider is needed to schedule a diagnostic mammogram.