On another forum there is a lot of speculation over whether or not Lori is still alive;
1. Carl didn't follow through and shoot her - Rick found the bullet, not the casing, and the bullet should still be in Lori's head.
2. Andrew survived a courtyard full of zombies, Hershel an amputation...but both lived
3. No body - a blood trail, and GN said on The Talking Dead that the zombies dragged her off and ate her. But when else did we see the zombies drag a carcass away?
4. No Carol - did she save Lori and too her to the prison hospital to fix her up?