Why couldn't it be? Seems like a no brainer. Wouldn't it be necessary to remove it, if only because it might migrate.
There are better places to store bullets than body parts. I take it you can't go to the hospital.
I would presume a bullet COULD be surgically removed if it were necessary (since they can remove tumors and growths from the liver) -- whether or not it would actually NEED to be removed would probably be an entirely different question. Perhaps that would depend on what the bullet was made of and where it was lodged within the liver...
You should speak with a doctor about that. Generally, too much lead is not good for the liver. It might be iron I'm thinking about.