The diameter of the normal appendix is less than 0.6 cm, and the length varies from person to person, from a short appendix of 3-4 cm to a longer appendix of more than 8-10 cm. If the diameter of the appendix exceeds 0.6 cm, there is fluid in the appendix cavity, or there is a fecal stone in the appendix cavity, or there is oozing around the appendix, and there is obvious pain when the ultrasound probe is pressed on the abdomen, it is usually a sign of acute appendicitis. After the diagnosis of acute appendicitis is clear, surgery is usually required because appendicitis is prone to appendiceal perforation after conservative treatment.