Welcome! I would call the member service # on your CIGNA insurance card and tell them what you are wanting, and see if they can find out the requirements. I work for CIGNA, and every policy is different, but, most of them want a 6 month supervised diet, 5 years of weight loss history as well as a referral from your primary doctor stating that this surgery is medically necessary.
I started out by checking my benefits to make sure that it was not an exclusion on your policy (if it happens to be, then you dont even have to bother with insurance, they wont cover it no matter what) then I made an appointment with my family doctor and told him what I wanted and he made the referral to my surgeon and they worked with me at their office in regards to insurance.
Good luck!!