Acute appendicitis is a common surgical condition, ranking first among the various acute abdominal conditions. It can occur at any age, but is of course more common in adolescents. 70%-80% of the abdominal pain in acute appendicitis is characterized by early paroxysmal pain around the umbilicus and upper abdomen in an irregular location, followed by metastatic right lower abdominal pain after a few hours, with persistent heavy pain; the abdominal pain varies in different locations and pathological types of appendicitis. Many clinical signs and symptoms of acute appendicitis are similar to the following diseases, how can we differentiate them? Let’s share them together below. 1. Gastroduodenal ulcer perforation Perforated fluid may flow into the right lower abdomen along the paracolic sulcus of the ascending colon, and there may be similar metastatic right lower abdominal pain, much like the pain of acute appendicitis. However, the patient has a previous history of peptic ulcer, usually with sudden onset and severe pain. On examination, in addition to right lower abdominal pressure pain, the epigastrium still has pain and pressure pain, and peritoneal irritation symptoms such as abdominal muscle tension and loss of bowel sounds are more obvious. 2, acute mesenteric lymphadenitis This disease is common in children and is usually preceded by upper respiratory tract infection. The abdominal pressure pain is intermediate, less fixed and wider in scope, and can change with position. 3. Infectious disease of the biliary system It is easily confused with high appendicitis, but there is obvious colic, high fever, and even jaundice. The examination may be positive for Murphy’s sign, and generally there is often a history of recurrent right upper abdominal pain. CT shows an irregular soft tissue mass in the intestinal lumen with significant enhancement and the presence of surrounding fatty spaces. 5, Crohn’s disease lesions mainly occur in the terminal ileum, a non-specific inflammatory disease, more common in young people aged 20-30 years. In the acute phase of the disease, the intestinal canal at the lesion is congested, edematous and oozing, stimulating the peritoneum of the right lower abdominal wall layer, with abdominal pain and pressure pain, similar to acute appendicitis. The location is limited to the ileum and is not characterized by metastatic abdominal pain, and the abdominal signs are also more extensive, and sometimes an enlarged intestinal canal can be palpated. In addition, the patient may have diarrhea and a stool examination with significant abnormal components. Acute appendicitis usually has a normal temperature at the initial onset, and after a period of time, low or moderate fever may develop, and high fever is less common. There is pressure pain and rebound pain in the right lower abdomen. Generally speaking, the degree of pressure pain and rebound pain in the right lower abdomen directly reflects the degree of the disease, if the pressure pain and rebound pain are mild, the disease is also mild, on the contrary, the disease may be more severe, or even perforation may occur. Of course, appendicitis in the elderly and in children has its own characteristics: the elderly are relatively insensitive to pain, while children develop faster and are more prone to perforation. In mild appendicitis, most can be cured with antibiotic injections, but a significant number of patients require surgery. Therefore, when acute appendicitis is suspected, treatment should be sought at the earliest possible time to prevent complications.