Other shellfish poisoning, undetermined, sequela

This code signifies a long-term or residual effect stemming from an unspecified type of shellfish poisoning. It indicates that the acute phase of the poisoning has resolved, but the patient continues to experience health issues directly attributable to the past exposure. The specific type of shellfish or toxin involved remains unknown.

Use this code when documenting a patient presenting with persistent symptoms (e.g., chronic neurological issues, ongoing gastrointestinal problems, or other lasting sequelae) that are clearly linked to a prior episode of shellfish poisoning, but the exact type of shellfish or toxin was never identified. This code is appropriate for follow-up encounters addressing these long-term complications.

• Always assign this code as a secondary diagnosis, following the code for the specific sequela (e.g., chronic diarrhea, peripheral neuropathy).
• Ensure documentation clearly establishes a causal link between the past shellfish poisoning and the current residual condition.
• This "S" seventh character indicates a sequela; do not use for acute or initial encounters.