Thanks for the replies. Cameron, most articles write about not breaking the egg, but I've read some that says sometimes you need to puncture the egg (it has to be quite close to the vent to extricate the shells) but I'm not sure if I can do that cos I don't want to hurt her (plus like you said, there might be a risk of infection). I've sat her in our bath for about half an hour, with her legs all splayed out earlier, but no luck. She's in a box in the other room, asleep at the moment.
julia, there's a whole list of symptoms, including a hen dragging her bum low on the ground, runny, messy bottom, fluffing of feathers etc, but the easiest way to tell is by touching her bottom area, my chook's is distended and rock hard, and her vent is protruding as well. She's been poorly with infectious bronchitis earlier, and got better, and I didn't think she was going to lay again, which was fine by me, but I didn't expect her to get eggbound
