In clinical practice muscle guarding, pressure pain, and rebound pain are often simply referred to as the triad of peritonitis. The underlying cause of pressure pain and rebound pain is the pressure point, which is where the lesion is located, and through physical examination by the physician, for example, fixed pressure pain at the right lower abdominal mydriatic point can occur in acute appendicitis, and fixed pressure pain under the ribs in the right upper abdomen can occur in acute cholecystitis. In contrast, rebound pain means that the patient relaxes, and then the doctor gently presses his finger down deeply at the site of the pressure point and suddenly relaxes, and if the patient feels pain, it is called a positive rebound pain. Positive rebound pain clinically represents a clinical symptom of localized peritonitis, that is, a clinical symptom that occurs when the localized infection or abscess irritates the peritoneal somatic nerve in the wall. However, at present, pressure pain and rebound pain are only a sign of physical examination, and the exact diagnosis of combined peritonitis usually requires further ultrasound or CT examination of the abdomen to clarify the diagnosis, and emergency surgery is usually required after the diagnosis is clear.