Hi I had a hen I noticed this morning with a prolasped vent. I brought inside the house, washed the area and applied some lubricant while feeling for an egg/pushing the prolapse back. She kept pushing it out and after a minute or so passed a very large fluid filled sac that looked like a water balloon. Unfortunately I didn't take a picture before I popped it to see what was inside. It appeared to be a very watery fluid. The sac itself appeared clear with what looked like blood vessels on the surface of the sack. The sack was oval shaped about 2" X 4" which seemed fairly large to pass through such a small vent but it was water filled so it was pliable. Any ideas on what this could be............I have seen ascites but it was a completely unattached sac that was passed. It was the Black Australorp seen in my avatar. Thank you.