I found this on another website. Hope it helps & good luck.
What if the yolk sack is not completely absorbed when you open the egg? When I begin an assisted hatch, I always have a brooder set up....just in case I need it. If I check to see if the yolk sack is absorbed and find that it isn't, I stop right there! The chick is put into the brooder, eggshell and all. The shell is what protects the yolk sack so that it doesn't break before it's absorbed. A chick at this stage can't be given back to its parents until everything is stabile. After this, there's nothing to do except watch and wait. It can take anywhere from 2 to 15 hours or more before the lower portion of the shell can be removed. No food is needed. The chick just needs enough moisture to allow the hatching process to complete itself.