Appendicitis is thought to be caused by a blockage of the appendiceal lumen, which can be caused by lymphoid hyperplasia, a fecalith, a foreign body, or even worms. Distention, bacterial overgrowth, ischemia, and inflammation are all symptoms of obstruction. Necrosis, gangrene, and perforation can result if left untreated. An appendiceal abscess occurs when the perforation is confined by the omentum.