Secondary peritonitis is one of the most common types of acute abdominal conditions, most often due to acute appendicitis, pancreatitis, and gynecologic inflammation. Patients may present with abdominal pain with significant primary lesions, with pressure rebound pain and muscle tension. In some patients, the initial pain in the upper abdomen progresses to total abdominal pain and finally to a plate-like abdominal change, accompanied by fever, nausea and vomiting, due to perforation of the upper gastrointestinal tract and flow of gastric juice or bile into the abdomen. In some patients, the rupture of a substantial organ due to trauma, such as liver rupture or spleen rupture, results in a bloody abdomen, and the flow of bile into the abdominal cavity also causes significant irritating pain. Usually, surgical treatment is required, and symptomatic anti-infective treatment is systematically administered. Patients with appendicitis should have the primary lesion removed, and should be removed from bed early after surgery, as open surgery is prone to complications of intestinal adhesions and intestinal obstruction.