If they are egg bound, yes. According to what my vet told me, the ovaries continue to release eggs into the blocked up uterus. The eggs that can't make it out will break and the body temp of the hen will "cook" the egg matter inside her, and eventually this will congealed egg matter will become infected. Sometimes they can still pass eggs/egg matter through even when they are bound.
I noticed something was up with my hen when she was acting just off (lethargic, wings down, ruffled feathers), and noticed what appeared to be egg white coming out of her vent. When I separated her, I noticed she passed a few shell-less eggs. I had no idea what those were! She had probably been passing them in the coop, but they were eaten either by her or the other hens. I was able to get some egg stuff out of her, but I knew that for me (a total newbie) - this was a job best left up to a professional. I got her into the vet within 48 hours of her acting funny, but by then it was too late.
But my hen didn't have that white spot/area on her rear end, or at least I didn't notice that. Her bum was bald when we adopted her - and the vet is pretty certain based on timing that she was already egg bound when we got her.
