According to the Guardian http://www.guardian.co.uk/Iraq/Story/0,2763,928531,00.html
divisions of the Republican Guard were never allowed into Baghdad due to their questionable loyalty, there was a fear of a coup d'etat. Saddams trusted protectors are the 20,000 Special Republican Guard who are trained in urban warfare. By leaving the Republican Guard outside of Baghdad they are being decimated, already one down and another going, with two sidelined. To save the remainder he may have them to retreat into Baghdad, possibly jeopardising his own position.
