I would guess that the best thing would be to pump the milk (blood).
This will allow her to stimulate the breast, get rid of the blood that
is there (and there could be a lot) which will also decrease the
probability of infection.  As soon as she is up to it, she should put
the baby to the breast even if he drinks blood (he may spit up, warn
her).

Jack Newman, MD, FRCPC