Injury of olfactory [1st ] nerve, unspecified side, sequela

This code signifies a long-term or late effect resulting from a past injury to the olfactory nerve, which is responsible for the sense of smell. It indicates that the specific side of the injury (left or right) is not documented. This sequela could manifest as persistent anosmia, hyposmia, or parosmia following the initial trauma.

Use this code when documenting a patient presenting with a chronic or residual symptom directly attributable to a previous injury of the olfactory nerve, and the laterality is not specified in the medical record. This code is appropriate when the acute phase of the injury has passed, and the patient is now experiencing a lasting complication. Documentation should clearly link the current symptom to a prior olfactory nerve injury.

• Always assign a sequela code (ending in 'S') for late effects of injuries, not for the acute injury itself.
• Ensure documentation explicitly states the cause of the olfactory nerve injury (e.g., head trauma, surgery) if known, and code it first if it's still relevant to the current encounter.
• If the laterality (left or right) of the olfactory nerve injury is documented, use the more specific codes S04.811S (right) or S04.812S (left) instead.