Ruptured appendix. Computer artwork of a person's abdomen showing the intestines (coiled). At the end of the large intestine (colon, dark beige) the appendix (lower left) has ruptured, releasing bacteria and faecal matter (brown patches) into the abdominal cavity. This causes serious infection, leading to a whole-body inflammatory response (sepsis) and inflammation of the lining (peritoneum) of the abdominal cavity, known as peritonitis. This is a serious medical condition and is life-threatening without emergency medical treatment.