Inpatient pre approval

Hello, I am new to this message board and very grateful I found it.  Any suggestions would be appreciated.  Here's my question.  My insuance company, BCBS of MD, will pre approve WLS if the procedure is in inpatient.  If it's outpatient, you have to have the surgery then they'll review it.  Is there any way to get around that?  My Dr. only does inpatient for the Lap Band.  Has anyone ever come across this and been able to get pre approval.  Of course the Dr. won't perform the surgery unless they have approval from the insurance Co.   Thank you. Debbie