The abdomen is at the front of the body, below the chest and above the pelvis. There are many organs within the abdomen, including the liver, spleen, stomach, small intestine, large intestine, appendix, pancreas, kidneys, and ureter. If abdominal pain occurs or a mass develops in the abdomen, you should go to the hospital for an examination to clarify the location of the pain or the source of the mass. If pain occurs in the right upper abdomen, gallbladder stones with cholecystitis are usually considered. If pain occurs in the upper middle abdomen, gastritis or gastric ulcer is usually considered, and pain in the lower right abdomen is usually considered appendicitis. After the diagnosis is clear, then decide the treatment plan. If there is a mass in the abdominal cavity, it may be a malignant tumor or a benign mass, which needs to be further clarified by abdominal CT and gastroenteroscopy if necessary, to decide the next treatment plan.