For one service my providers bill now, TAP blocks, we bill two codes in direct contradiction of Correct Coding Initiative suggested methods. 64486 for the TAP block and 76942 for the guidance. 64486 specifically is inclusive of guidance. Now, most payers pay the 64486 line and remark/writeoff the guidance code as unbundling, but some pay on each line (for about as much total as other payers pay on the one line). I can't speak to which payers specifically as I mostly code now, and payment posting was never my specialty. What I'm getting at is that your code may be a similar situation, in that two codes may be preferrable for the payer for whatever reason. Maybe they track payments disbursed by the type of service, and they separate out ultrasonic guidance from surgical procedures, for example.
Perhaps there is an Aetna CPB covering this situation? Or maybe you could call Aetna and get through to a claims auditing manager to find out if they have a preferred format? Sorry that wasn't much of an answer, but at least there are still some paths forward besides just blindly appealing each denial. I would start by trying to find the relevant clinical policy bulletin, as that's what the Aetna claims reps are going to tell you to do if you speak to them first.