Peritonitis is usually detected by performing a physical examination, routine blood, urine, C-reactive protein, abdominal x-ray, abdominal ultrasound, and abdominal CT. When the peritoneum is stimulated by bacterial infection, chemical irritation, or physical injury, an inflammatory response occurs and it is called peritonitis. Patients with peritonitis will have symptoms such as abdominal pain, nausea, vomiting, etc. As the disease progresses, there will be systemic symptoms of infection such as fever, increased heart rate, increased respiratory rate, and so on. In severe cases, there may be impaired consciousness, coma, and shock. Doctors will usually examine the patient, such as abdominal percussion, palpation, auscultation, etc., and will find that the patient will have abdominal pressure, rebound pain, muscle tension, and abdominal cavity will have mobile turbid sounds. In addition, patients usually undergo laboratory tests such as routine blood, urine, and C-reactive protein to determine whether inflammation exists in the body. Abdominal X-rays are performed to help find out if the patient has complications such as intestinal obstruction, abdominal ultrasound can help clarify the cause of peritonitis in patients, and abdominal CT can help find out if there is any abdominal fluid buildup. In general, the doctor can basically clarify the diagnosis of peritonitis based on the patient’s medical history, symptoms, physical examination results, as well as other auxiliary tests.