I'm responding from personal experience only and am definitely not a
pediatric GI specialist.  The blood in our daughter's stools was similar
to that found infrequently in egg yolks--you could easily remove it and
it was always red.  It 1st appeared around 4 mos of age.  After many
blood tests and the round of physicians, a pediatric gastroenterologist
determined that ours was a hyper-immune response of the intestines
"caused" primarily by BF.  (Read on...it's a good ending.)  Her immune
system was in such high gear that "extra" lymphatic-like tissue grew in
small nodules in her colon and when she eliminated, the fecal matter
sometimes caused the nodules to slough off.  He said that the "problem"
used to be quite common until ABM became the norm and said that many
docs forget that, in most babies who present with this, it's quite
normal (he was quick to say that you need to rule out allergies and IBD,
etc.).  The best thing was that he said to keep BF for as long as
possible...after 31 months I'm not sure when "as long" will end :).  The
blood disappeared from her stools when she was about 9 mos. old.