We all have to remember that it is NORMAL for a breastfed infant of 6 wk-6
months to have infrequent bowel movements.  If the baby is thriving and the
stools, when they occur, are soft/loose, there is nothing to worry about and
no need to do any testing of any sort.  If, however, the baby has difficulty
passing stools, or they are actually firm, or there is some other reason to
suspect a congenital anomaly (such as Hirschprung's), then the GI workup would
be indicated.
Linda L. Shaw MD FAAP
Altoona PA