Patients were identified according to the International Classification of Diseases, Ninth Revision, Clinical Modification Code for AP (577.0). AP was diagnosed if 2 or more of the following findings were present: characteristic abdominal pain; serum amylase or lipase level 3 or more times higher than the upper limit of normal (i.e., > 210 U/L and 180 U/L, respectively); and an imaging study (CT, magnetic resonance imaging [MRI], or transabdominal sonography) showing changes consistent with acute pancreatitis. Patients receiving an abdominal CT scan within 24 hours after AP onset and admission were considered eligible for the study. The onset of AP was defined as the time of abdominal pain onset. After the etiology and risk stratification of patients were confirmed, appropriate treatment and nursing were implemented, such as prevention and treatment of shock, improving microcirculation, spasmolysis, acetanilide, inhibiting pancreatic enzyme secretion, anti-infection measures, nutritional support, prevention of complications, intensive care measures, and so on. Patients with gallstone pancreatitis were treated with endoscopic retrograde cholangiopancreatography (ERCP), endoscopic sphincterotomy (EST), or cholecystectomy. After CT, ultrasound- or endoscopic ultrasound- guided puncture drainage was implemented, and patients suspected of infection underwent surgery in addition to drainage.