Reovirus as the cause of diseases classified elsewhere

This code identifies reovirus as the etiologic agent responsible for a disease process primarily classified under another ICD-10-CM code. Reoviruses are non-enveloped RNA viruses that can cause a range of symptoms, including respiratory and gastrointestinal infections, though often subclinically. This code is used when the reovirus infection is confirmed and is the underlying cause of a condition coded elsewhere.

Apply this code when medical record documentation explicitly states reovirus as the causative organism for a disease. This typically occurs in cases of confirmed viral gastroenteritis, respiratory infections, or other systemic conditions where laboratory testing (e.g., PCR, viral culture) has identified reovirus. The primary disease manifestation will be coded first, followed by this code to specify the etiology.

• Always sequence this code as a secondary diagnosis, following the code for the specific disease caused by the reovirus.
• Ensure documentation clearly links the reovirus to the primary condition; a positive test alone without clinical correlation may not suffice.
• Do not use this code for asymptomatic carriage or incidental findings of reovirus without an associated disease.