Acute appendicitis is often preceded by abdominal pain and followed by fever, the patient first has abdominal pain and gradually aggravated, and the right lower abdominal pressure pain is obvious, the pressure pain point is fixed, there is obvious rebound pain and muscle tension, and then fever occurs. The blood picture shows a markedly increased white blood cell count, with relatively high neutrophils, and ultrasound reveals a swollen appendix, which may be surrounded by enlarged lymph nodes. Acute mesenteric lymphadenitis is often preceded by fever and then abdominal pain, the patient first has fever and other infections, followed by abdominal pain, abdominal pain is often manifested as vague pain or cramping pain, the patient does not feel uncomfortable between the two pains, most common in the right lower abdomen, the area of pressure and pain is close to the midline or high, but the location is not fixed, there is no rebound pain and muscle tension. The patient’s white blood cell count is usually normal or slightly elevated, and lymphocytes are relatively high.