Perplexed by abdomen distention and swelling.

I have a hen (SLW) that is no longer laying (for over a year) who has been lethargic lately. I knew her time was coming, as she's an old girl and had a good life.
She sleeps on the floor of the coop instead of the perch, and sometimes lays down to eat.

Today I was feeding her from my hand and decided to pick her up and put her on my lap to have some "mommy time," before she goes. I noticed how full and swollen her abdomen is.

I have read several threads on here and many birds seem to be not eating or pooping.
Jackie eats and drinks fine. She also passes poop fine. There is no egg. I have bathed her and checked her vent.

I am to the point I am assuming cancer/tumors/water (all obviously connected ) but do not know if there is a way to drain any of the fluid to make her more comfortable.

I would like to let her live out her days in the sun, but if there is anything I can do to make her more comfortable, I would prefer to.

Thank you in advance.