Okay, that makes sense. Your issue isn’t related to an external cause code. (It’s actually not common for an external cause code to cause a claim denial, which is why I asked for the specific denial reason.)
F07.81 has a “Code First” note instructing you to code the underlying physiological condition first.
The patient has post-concussion syndrome, but what specifically was the patient being seen for at that encounter? What was being evaluated or treated that day? That should generally be your primary diagnosis.
Your sequela code usage is fine. That falls under the “code also if applicable” note.
(One thing to note, though: S06.0X9S indicates that there was loss of consciousness of unspecified duration with the concussion. If the provider knows the duration of the loss of consciousness at the time of the concussion, then the more specific sequela code should be assigned instead. But aside from adding specificity if available, the use of the sequela code is appropriate.)
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