The most common causes are the following: 1. gastric ulcer, which is clinically manifested as subxiphoid pain after meals, accompanied by heartburn and acid reflux. 2. chronic gastritis, including chronic superficial gastritis and chronic atrophic gastritis. The clinical manifestations are subxiphoid pain with abdominal distension and belching. 3. chronic enteritis, the main clinical manifestations are recurrent abdominal pain, often accompanied by diarrhea, and in severe cases, blood in the stool, and it is recommended to improve routine stool examination and colonoscopy to assist in the diagnosis. In addition, if a girl has chronic appendicitis, chronic cholecystitis, etc. can cause abdominal pain, but it is relatively rare in clinical practice.