Appendicitis is a painful swelling of the appendix, which is a small, thin pouch about 5 to 10cm long that is connected to the large intestine where feces forms. The likely cause of appendicitis is a blockage in the lining of the appendix, which can cause an infection. The bacteria then multiply quickly, causing the appendix to become inflamed, swollen, and filled with pus. If not treated right away, the appendix can break open. The following are some of the common causes of inflammation, swelling, obstruction, and infection in the appendix:

• Blockage by a small, hard piece of stool (fecalith)
• A foreign body, such as a piece of food or a seed
• Tumor
• Worms
• Infection in the digestive tract
• Swelling in the appendix that reduces or closes the opening and traps more bacteria inside

If the obstruction causes inflammation and swelling, it could lead to increased pressure within the appendix, which may then burst. A burst appendix, also called a ruptured appendix, spreads infection throughout the abdomen, a condition called peritonitis. Peritonitis can be very serious and even cause death if not treated right away.