Coma doesn't necessarily mean brain damage. It means that your not conscious, which of course can be due to serious brain damage. But falling unconscious is a way of the body to protect the brain from further damage, because it needs less energy this way.
Losing a lot of blood would cause Lois to fall unconcious, because her blood pressure would drop. Besides, a lot of pain can also make people pass out. Even if Lois would get immediate help, I guess she'd remain unconscious for some time even if she gets blood and fluid. Or she'll slowly come to. But it would be safe to assume that she won't be fully awake at once.
