Okay, we’ll that is not ascites, but may be a sign of a cystic right oviduct. Chickens are born with a right and left oviduct. The right one ceases to function and shrivels up, while the left one produces eggs. If that right oviduct persists, it can become full of fluid and cause swelling in the abdomen which looks similar to ascites or water belly. I’m not sure if this will need to be drained again or not. Here is a brief explanation of this:
https://www.merckvetmanual.com/poul...ulation in the vestigial,15–20 cm in diameter.
https://www.merckvetmanual.com/poul...ulation in the vestigial,15–20 cm in diameter.