Infectious mononucleosis

This code identifies infectious mononucleosis, an acute viral infection typically caused by the Epstein-Barr virus (EBV). It is characterized by fever, pharyngitis, lymphadenopathy, and atypical lymphocytes in the peripheral blood. The condition can also present with splenomegaly and hepatomegaly.

Assign this code for confirmed diagnoses of infectious mononucleosis based on clinical presentation and laboratory findings, such as a positive monospot test or EBV serology. It is appropriate for both initial and subsequent encounters related to the acute phase of the illness.

• Do not use this code for chronic fatigue syndrome, even if a history of mononucleosis is present.
• Code any associated complications, such as splenic rupture (860.4) or hepatitis (573.3), separately.
• Ensure documentation specifies "infectious mononucleosis" rather than just "mononucleosis" to differentiate from other causes of mononucleosis-like syndromes.