That's not exactly how health insurance works. The insurer can always say something the doctor did is not covered, or something the doctor says you need is not

That's not exactly how health insurance works. The insurer can always say something the doctor did is not covered, or something the doctor says you need is not covered. Or that, while a procedure is covered under the policy, you aren't sick enough for the insurer to consider it medically necessary, even if the doctor thinks it is.