The suffix -itisitis means inflammation, so appendicitis is inflammation of the appendix. Appendicitis occurs when mucus, stool, or a combination of the two blocks the opening of the appendix that leads to the cecum.Bacteria proliferate in the trapped space and infect the lining of the appendix.he appendix is a small, pouch-like sac of tissue that is located in the first part of the colon (cecum) in the lower-right abdomen.