Question
How can kidney stones be pre-existing if you have never had a problem with your kidneys or stones before?

Does that mean a tonsillectomy would not be covered because your tonsils were already there?  what about your appendicts?  a hysterectomy? 

Blue Cross Blue Shield must have a different set of criteria than the rest.

The engineers that constructed our government were well aware of the weaknesses of mankind.  The three branches of government - executive. legislative, judicial - were established to guarantee representation in a legal and inpartial manner.  If one branch of our government fails,  there is always another level to support the will of the people.