The appendix is a finger-shaped tube 3-inches long extending from the right side of the large intestine. The exact function of this organ is not very clear. Appendicitis is a condition in which the appendix becomes inflamed and filled with pus. It is a medical emergency requiring immediate surgical removal of the appendix. If it is left untreated, there are chances the appendix will burst spreading the infectious material into the abdominal cavity (peritoneaum). This can inflame the abdominal cavity, a condition called peritonitis, and can sometimes be fatal if not treated urgently. Appendicitis can strike at any age, but is common between the ages of 10 and 30 years.