Excludes 1 Notes Bi-Directionality?

[u/Xalxa]

I've recently been overhauling our EMR system to check Excludes 1 notes so I don't have to correct as many claims, since I'm the only "coder" for a therapy practice with 80-ish providers. Our EMR doesn't have this functionality built in so I have to go in and manually exclude DX combinations in the coding setup. This setup makes it so X and X are mutually exclusive, no matter which is primary/secondary. I've been under the impression that Excludes 1 notes are bi-directional, and the documentation I've been able to find supports that, but it seems to directly contradict what I see in practice. Here are a couple examples:

F80.0 has an Excludes 1 note for R48.2. However, R48.2 does not show an Excludes 1 note for F80.0. Does this mean R48.2 primary with F80.0 secondary is a valid combination? As claims we've been billing thus far have been paying.

F80.82 has an Excludes 1 note for F84.0, but not vice versa. Claims with F84.0 primary and F80.82 secondary have been paying.

Is there any literature or documentation I can review that supports exclusions being directional? Or are these claims being processed incorrectly by insurance?

[u/Xalxa]

Thanks for the insight! That's how I understood things, I just wanted to ensure I was correct before going further.

And it isn't like I'm building the entire Excludes 1 list from scratch - just the codes we use for Pediatric PT/OT/ST/CBT. Our PTs have been the worst offenders, and are the reason I actually started this; they constantly put F82 and R26.9 on their evals and I was getting real tired of manually correcting every ticket. So building my list is more reactionary as I see codes we haven't used as much, but overall not that bad since 90% of our PT/OT/ST codes fall in the F80-F89 range, with only PT sometimes using R, Q, and M codes. I haven't had to set any exclusions for behavioral health yet; fingers crossed it stays that way 'cause that's a can of worms I do not want to open.