Will my hospital take BCBS?

I am currently scheduled for heart surgery at St Lukes in Wisconsin. I have Blue Choice Preferred Bronze PPO-701. When I search for the provider on BCBS website, it says that they do not take my plan. The hospital says they do take BCBS. How can I be certain that they are in the BCBS network? My surgery is scheduled for the 15th this month and I am afraid that my insurance will not cover the surgery and/or it is too late to transfer the surgery.