Not sure what kind of insurance you have but I have Aetna. I can get on their web site and get what they call a "Clinical Policy Bulletin" that describes in medical terms exactly what the criteria is for them to cover any particular treatment. I have gotten CPB for the WLS, for my gall bladder removal, for the panniculectomy, and abdomniplasty. If you call your insurance rep they might be able to send/fax you there version of this document. Since you (or someone) is paying for this insurance they have to have in writing somewhere what the policy is. You can't effectively argue that you meet their criteria unless you know what the criteria are.
My insurance considers abdomniplasty to be cosmetic and will not cover it at all. The criteria for the panniculectomy; however, was detailed and specific.
I made an appointment and went through it with my PCP (it's in medicalese). Their criteria included how big it was and that it caused repeated rashes that had been treated for at least 6 months without results. We then began documenting via photos and clinical visit notes that the pannus was larger than they required and that I had completed over 6 months of treatment with antibiotics and anit-fugal powders and it still recurred.