Ultra-sound can ususally (not always, but usually) tell lots of information
about lumps in breast.  It is not a useful broad screening technique like
mammagrams due to cost, etc.  It can distinguish (generally) between solid
and cystic lumps.  It can locate the borders of the lesions so they can be
aspirated for cytology.  The best and ultimate dx is obtained by excision,
but if the info provided by ultrasound and aspiration is pretty reasuring,
the biopsy might not be necessary.
Barbara

Barbara Wilson-Clay, BS, IBCLC
Private Practice, Austin, Texas
Owner, Lactnews On-Line Conference Page
http://moontower.com/bwc/lactnews.html