The causes of postoperative infection in appendicitis include wound infection, periappendiceal abscess, and portal phlebitis. Patients who have infections after appendicitis surgery should pay attention to regular dressing changes and antibiotic treatment. 1. Wound infection: after appendicitis surgery, the wound may be infected due to poor aseptic concept of surgical operation, no regular dressing change, incomplete suture, no timely clean up of exudate, and no effective anti-infection treatment after surgery. 2. Peri-appendiceal abscess: the appendix itself is already infected and the surrounding area is already suppurating. The operation is not complete, only the diseased appendix is removed, and the infection still exists in the abdominal cavity. This situation may require another caesarean section at a later stage. 3. Portal phlebitis: appendicitis itself is an infectious disease, when the inflamed vein back to the portal vein, it will cause portal phlebitis. Then there will be postoperative infection. Post-operative appendicitis patients should pay attention to regular dressing changes, and use effective antibiotic treatment to prevent wound infection. After the operation, it is necessary to go down to the ground early to promote intestinal peristalsis. If there are any abnormalities after the operation, you must inform your doctor in time.