What does a referral really mean?

My PCP sent me a copy of my referral papers.  I have an information session scheduled tomorrow with bariatric surgeon.  On the papers it says I've been approved for 12 visits to expire 06/05/08.  Who approves the visits---PCP or Insurance?  And if it's insurance, does it mean they're likely to approve surgery?  PLEASE HELP!

Your PCP contacts your insurance carrier to authorize a certain number of visits to see another Dr.  It does not mean they will approve your surgery though.