It is not always particularly painful to suffer from appendicitis. The pain of appendicitis is mainly caused by the following factors: i. The appendix is often blocked by fecal stones or proliferating lymphatic follicles. The fluid secreted by the appendix itself will increase the pressure in the appendiceal cavity. If the pressure is high, the pain will be intense, and if the pressure is low, the pain will be mild. When the pressure is too high there will be appendiceal perforation, then the patient will go from very painful to less painful, but after some time, the pus, fecal stone and intestinal fluid flowing out will stimulate the abdominal cavity and abdominal wall, and the pain will increase again. Second, when suffering from appendicitis, pain will be caused by the presence of purulent or inflammatory fluid in the periphery, which will irritate the peritoneum and the abdominal wall muscles. If the omentum and intestinal canal encase the appendix, the fluid cannot come out to stimulate and the pain will be mild. This is the reason why periappendiceal abscesses are heavily infected, but the pain is light instead.