Hi Michelle,
Technically it is the job of the Triple Burner to ensure fluids descend to the Bladder. An effusion, especially consisting of a transudate, suggests a Triple Burner obstruction. That fits with the sense of consilidation around the middle. In this case, you'd want to use a formula like Minor Bupleurum to open it back up, as well as deal with possible lymphoma and liver inflammation in real terms. That's what Open the Liver Canals does, so it's a great place to start. I'd give it a chance for a few days, unless the appetite is nil, before playing the prednisone card. That way, any improvements would suggest the formula choice is correct.
I hope that helps you out!
Steve