A high cytomegalovirus lgG is usually indicative of a previous cytomegalovirus infection that is currently in the recovery phase. Cytomegalovirus is a type of herpes virus that can be transmitted through the gastrointestinal tract, intimate contact, or mother-to-child route. After the first cytomegalovirus infection, the body is able to produce specific cellular and humoral immunity to inhibit viral replication, and therefore may appear positive for IgG antibodies. In serodiagnosis, IgG antibodies rise slowly during the course of viral infection and plateau for a longer period of time, and may carry IgG antibodies for life even after the virus is cleared. When immune function is normal, cytomegalovirus is in a suppressed state and does not harm the body. However, if the body’s immune function decreases, such as suffering from tumors, applying glucocorticoids, radiotherapy, chemotherapy, etc., cytomegalovirus may be activated and actively replicate in the body, harming the liver leading to hepatitis, the intestines leading to enteritis, and the central nervous system leading to encephalitis, etc. At present, IgG antibodies are mainly detected by enzyme-linked immunoassay and chemiluminescence method, which can provide a basis for clarifying previous infection and latent infection. Patients can improve other related tests under the guidance of doctors to determine whether further treatment is needed.