The diagnosis of bronchitis is usually based on the patient’s symptoms and combined with laboratory and imaging tests to finally confirm the diagnosis. The most typical symptoms of bronchitis are cough, sputum, fever, and of course some patients may also see general malaise, abdominal pain, diarrhea, and other symptoms of systemic toxicity, and the blood tests should be done as follows: 1. If the infection is caused by a virus, the white blood cells are usually normal or low, the lymphocytes are normally low or high, and the neutrophils are usually within the normal range. 2. 3. If the infection is caused by atypical pathogens such as mycoplasma and chlamydia, monocytes may be high, and neutrophils and white blood cells are often within the normal range. There are also chest films and lung CT, which can see thickened and disturbed texture in both lungs. The combination of symptoms, laboratory tests and imaging will allow for a definitive diagnosis.