Hi cerph! I'm so sorry you're in this position, believe me, I understand how difficult it is and I had to go thru something similar with a kidney biopsy. So here's the advice my nurse friend gave me:
When the doctors want to do an invasive test, or really any kind of test, ask these questions:
What is the test designed to prove, disprove, or reveal/illuminate?
How is this information going to affect treatment?
If the test says the treatment is necessary, are you going to go thru with the treatment?
In other words, is good knowledge going to come from the test? Are you willing to act on the knowledge? If the answer to either question is no, you probably don't want to to do the test.
I went thru with my biopsy because I wanted to know the extent of the damage, but I didn't want to go through with the treatment if a certain disease was diagnosed from the biopsy, as the treatment is similar to cancer - blech!
The liver is different from the kidneys in that they regenerate a lot faster and easier, so long as the bile ducts are stone-free. So you may have less reason than I to do this type of test.
I hope that helps. :)