Although it is the hospital and/or doctor that makes the decision it is the insurance company that drives the decision.
That suggests that insurance companies write, practically literally, hospital rule books.
How much deeper into a doctor's practice does that get? (My recent experience has been that unless they're pushed to the wall, doctors won't even answer questions. [Does that suggest that they're simply careful... or actually vulnerable?])
Some day I've got to whack Bruce Davis, the owner of 1-800-LAWYYERS, on the side of the head with a paving stone for spearheading almost unimaginable damage to America's medical and legal systems (not to say that it wouldn't have been someone else had it not been him).