What is an Appendicitis? Appendicitis is an inflammation of the appendix, a finger-shaped pouch on the lower right side of your belly that extends from your colon. The pain in your lower right abdomen is caused by appendicitis. In most patients, however, discomfort begins around the navel and progresses. Consult our laparoscopic surgeon in Pune and Pimpri Chinchwad for more information!