I do not have documentation except our own experience.  This is
anecdotal, obviously.  However, surgeons do not know, it has surprised
me to learn, that continuing breastfeeding on only one side allows
milk to dry up on the other.  This seems to be an important piece of
missing information in their training.  Even one quite knowledgeable
and breastfeeding supportive surgeon I recently referred to was
surprised that this was possible.

There is no need to stop breastfeeding on either side.  Lots of
mothers have had biopsies without stopping even on the affected side.

Why not do a needle biopsy first?  This is much easier and much less
likely to result in the milk fistula which so worries so many
surgeons.

Finally, if she does have an open biopsy, make sure she knows not to
have a periareolar incision.

Jack Newman, MD, FRCPC