The appendix is a narrow, muscular, worm-like outgrowth from the caecal part of the large intestine. It is also called the vermiform appendix due to its worm-like shape. It is usually about four inches long. It is considered a vestigial organ in humans with no known function; however, in animals it helps in the digestion of cellulose from plants. Surgical removal of the appendix does not appear to affect the health or normal biological functions in humans. The appendix has an abundant collection of lymphoid cells, which defends the body against infectious microorganisms. Appendicitis and carcinoid tumours are the most common diseases affecting the appendix.
Appendicitis is a condition characterized by inflammation of the appendix. It usually occurs due to blockade of the opening of the appendix with debris or indigestible food, passing through the large intestine. Most people with appendicitis experience pain, fever, nausea, vomiting, and loss of appetite. Surgical removal of the appendix or appendectomy is the standard treatment for appendicitis. A 3–6 cm horizontal incision is made in the lower part of the abdomen on the right side, through which the appendix is removed. Alternately, the appendix can be removed by a keyhole operation or the insertion of a three-fibre optic camera through the stomach (laparoscopy).