Wife is a nurse. Required surgery for lifesaving/severe disability (inherited congenital, killed her father). Insurance was Aetna and Hospital Self Insured. Surgery recommended by world class surgeon she worked with.
Finally pre-approved on 3rd appeal after 8 months and 150pages of documentation of every piece of every single communication (who, when, response, expected next contact) only weeks before surgery scheduled >6 months before. First rejection was automatic, second was revealed to be a dermatologist, third was a gynecologist. (They really hated that we figured out who the person was, their specialty, the state they worked in, and pending disciplinary actions).
Standard answer is we can't tell you why you were rejected (code only) because the criteria are from a third party and their review document is proprietary. When you find an online leaked document with the same code it says "unnecessary cosmetic surgery". Wrong contact numbers are provided, people go on vacation and do not respond for weeks, "that person doesn't work here".
If you're not a professional in the field with time on your hands and a detail oriented A-hole, you will be denied anything expensive that isn't considered immediately lifesaving at a trauma ICU recommended by the attending.
After pre-approved surgery with excessive blood loss and an extra 12 hours in recovery... Overcharge/All-claims-denied. Multiple appeals until involving Hospital CFO who agrees to split the extra (self-insured) cost of the insurer and get the final insurance reimbursement check... it is $3k less than promised (hospital paid the correct amount). Surgeon was going to start charging late fees and interest or send it to collection after 4 months.
Is it worth fighting any more? No.