Egg binding occurs when a too large egg gets stuck just inside the vent. It can be extremely serious condition , especially if the bird goes into shock. If the hen does not remain bright and alert, take measures to keep her warm. The first thing to do is to make sure she is truly egg bound. If she is straining to release an egg, and you see the end of the egg near the opening, then you know for certain. If you can't see the egg, you can verify egg binding by lubricating a finger with K-Y Jelly or other water-based lubricant and gently inserting it into the vent until you feel the hard egg shell with the end of you finger. Don't attempt to stretch the vent, as you may tear her delicate tissue. Sometimes lubricating the vent area, and as much of the egg as you can not reach with a finger,will aid its passage. Gently squirting in warm water (not hot) saline solution wound wash, or soapy water, may help get things moving. Warming up the vent area may relax the muscles enough to release the egg. If the hen is tame enough not to be frightened by being handled, moisten an old towel, warm in the microwave ( make sure its not hot), and apply it to her bottom. Reheat the towel as needed to keep it warm, or better yet use two towels and warm them alternately, to maintain moist heat. An alternative warming method is to put warm, not hot, water in a bucket or basin and stand the hen in it with the water reaching just above the vent. After warming the hen's bottom for 15 minutes, give her a rest, and if she doesn't release the egg, try again. If warmth therapy still doesn't work, maybe you can dislodge the egg. Again lubricate the vent and egg with K-Y Jelly and/or warm soapy water. Gently insert your lubricated finger to help maneuver the egg, while with your other push gently against the bottom and try to work the egg out. Be careful here- you dont want to break the egg, which can cause internal injury. If all fails, you may need to collapse the shell to remove the egg. This maneuver is tricky and can injure the hen unless you work slowly and carefully. First suck out the contents of the egg by piercing the shell with a needle at the end of a syringe. Use a large-bore needle, 18 or lower guage, or emptying the shell will take forever. Once the shell is empty is empty of its yolk and white, try to collapse it while keeping the shards together. This part is the trickiest, as you must take great care to avoid injuring the hen with sharp shard. For this reason, dont squeeze the hen's abdomen to crush the shell, or at least on or two fingers on the inside and the other hand gently pressing from the outside. Using lots of warm saline or soapy water as a lubricant, carefully remove as much of the shell as possible, then rinse away the remaining pieces with squirts of saline gentle enough not to wash the shell bits deeper. Dont worry about getting the last little bit; once the egg is out, the hen is better off left to rest, and any bits left behind should come out on its own. If tissues protrudes through the vent, treat the hen as you would for prolapse.
Hope this helps!
Hannah