Primary is when one of the organs in the body becomes diseased, such as inflammation or tumor growth, which is called primary. Secondary is when there is a problem elsewhere that affects another organ, and this is called secondary. For example, primary appendicitis and secondary appendicitis are called primary appendicitis if the appendix becomes infected with bacteria due to a low immune system, or if the appendix becomes blocked due to an embedded fecal stone in the appendix cavity, causing inflammation of the appendix. If there is inflammation in the abdominal cavity, such as pelvic inflammatory disease or inflammation elsewhere, and the appendix becomes inflamed, then the appendicitis is called secondary appendicitis.