I had an instance where the hospital had coded my spouse's eye issue as "routine" -- so it was not covered by medical insurance, because your vision insurance is supposed to cover that. Our vision insurance wouldn't cover it, because they only permit one visit per calendar year.

The doctor that treated my spouse literally published a paper about the case, so uh... not routine. I got super lucky with the insurance person, though -- she actually called the hospital for me and got them to re-code it.