I had a breast biopsy while breastfeeding, although my son was 2 1/2 at the
time.  I have since talked to many mothers having breast biopsies with
younger babies.  Many surgeons are not comfortable with this, so it is
important to find one who has done surgery on the lactating breast.  It is
more difficult for the surgeon because there are so many more blood vessels.
 I know with mine, it took much longer and required much more frequent
electrocautery of bleeders than the ones I had when not lactating.  But it is
certainly possible and there is no need to wean.  The mom should request an
incision as far away from the nipple as possible.
     According to my surgeon, as well as things I have read, the main
possible complication is leaking milk from the surgical site.  But he said a
drain can be put in to deal with that.  Baby can nurse as soon after surgery
as is comfortable for mom.  In fact, my surgeon encouraged nursing within a
few hours, since engorgement might be more of a problem.   Good luck !
              Miriam Levitt<[log in to unmask]