I have a "what if question"
That depends on your insurance, so none of us can answer this for you. Some companies will cover it; some will not. You really need to contact your insurance company. Certain things -- like gallbladder -- should be covered by all, but if you get a leak, that could be excluded, depending on how the insurance policy is written.
I have BCBS - there is nothing in our entire written policy re: WLS. I had to call the 800 number, give them my employers group number and they looked it up. I then asked them to send me the detail via US mail. ( so I had it in writing) I also reviewed the definition of pre-existing condition. Which in our policy is anything you've been treated for within 6 months of your enrollment date with BCBS...so I am ok. Lined up my personal Doc to do labs and treat anything - and he was much more open and accepting - of my decision that I could ever have imagined. He is actually happy for me and very supportive..