A medical history and physical exam are the most important ways a doctor can diagnose mono. During the medical history and physical exam, your doctor will ask questions about your symptoms and possible exposure to the disease. Your doctor will also examine you for signs of the infection. This may include looking at your throat, checking your skin, and pressing on your abdomen.

Blood tests to help confirm the diagnosis include:

• Mononucleosis tests (including the monospot test and EBV antibody test). It is possible for the monospot test to come back negative early in the course of the infection (false negative).
• Complete blood count (CBC). A CBC may be done to rule out other infections or complications of mono.

Other tests may be done if complications of mono occur or if the mononucleosis tests are negative.

• Liver tests may be done to find out whether the virus has affected your liver.
• If the mononucleosis test is negative, your doctor may test you for an infection with cytomegalovirus (CMV) or other organisms. CMV can cause a mono-like illness.