Appendicitis (appendicitis) is a common abdominal surgical condition that can occur in people of any age, and is especially common in adolescents. Clinically, it often presents with right lower abdominal pain, elevated body temperature, vomiting and neutrophilia. Appendicitis is an inflammatory change of the appendix due to a variety of factors and is a common surgical condition whose prognosis depends on timely diagnosis and treatment. Early diagnosis and treatment can lead to short-term recovery; if the diagnosis and treatment are delayed, it can lead to serious complications, such as peritonitis due to appendiceal perforation, or even death. Clinically, there is often metastatic right lower abdominal pain, elevated body temperature, vomiting and increased neutrophil count. Clinical manifestations: 1. Right lower abdominal pain About 55% of patients start with pain in the left upper abdomen or around the umbilicus, resembling an attack of stomach pain, which shifts to right lower abdominal pain after a few hours, with persistent distension and worsening paroxysms. When gangrene of the appendix occurs, a more intense throbbing pain may occur, and when the appendix is perforated before, the pain is particularly severe, and once perforated, the contents of the appendiceal cavity flow out, the pain seems to be relieved, but the scope is enlarged. At this time, pressing the abdomen with the hand feels very hard, and the abdominal pain increases when pressing, pressing the right lower abdomen with the hand, and then lifting the hand violently, the abdominal pain becomes more intense called rebound pain, which is the occurrence of peritonitis. The location of the appendix is different for each person, and the abdominal pain that occurs is also different. A high appendix may manifest as right lower back pain, while a low appendix has lower abdominal cramping pain. Because of the variation in the degree and location of abdominal pain, acute appendicitis is often misdiagnosed as other diseases, especially in the elderly and pediatric patients. Therefore, in clinical practice, whenever acute abdominal pain occurs, it should be differentiated from appendicitis to avoid delaying treatment and making a serious illness. 2, general performance Patients can appear nausea, vomiting 1 to 2 times that is stopped, and there is loss of appetite, abdominal distension, diarrhea and other symptoms. Patients prefer to lie on their side in a bent knee position. Some patients have fever, headache, general weakness, and increased total leukocyte count in blood tests. 3, the performance of pediatric acute appendicitis under 12 years of age accounted for about 4% to 5% of the incidence. Before the onset of the disease, there are mostly colds, tonsillitis, diarrhea and other triggers, manifested as chills, fever, nausea, vomiting and diarrhea, the location of abdominal pain can be in the right lower abdomen, around the navel or the whole abdomen, careful examination of the abdomen, but still the right lower abdomen pressure pain is obvious. Pediatric appendicitis is highly susceptible to appendiceal perforation, and the abdomen remains soft after perforation, which, coupled with unclear pediatric narrative, can easily be misdiagnosed and lead to aggravation of the condition. 4, the performance of acute appendicitis in the elderly The symptoms at the beginning are mild and the pain is not heavy, which does not attract attention. The appendiceal wall of the elderly is atrophied and thin and brittle, prone to perforation and necrosis, plus the elderly often suffer from diabetes, heart disease, hypertension and other chronic diseases, causing difficulties in treatment, and the mortality rate increases with age, so we must be vigilant and examine carefully to prevent missed diagnosis and misdiagnosis.