Peritonitis Say: pare-uh-tuh-NY-tis When you get a stomachache, it might be an actual problem right in your stomach, but not necessarily. The problem could be in your abdomen. Your abdomen is more than your stomach and more than your intestines. It's the whole area between your chest and your hipbones. Peritonitis is when the tissue that covers the inside wall of the abdomen gets swollen and irritated, usually due to an infection. Appendicitis can cause peritonitis if it isn't treated before the appendix bursts. Back to Articles Related Articles Stomachaches Ugh. Bellyaches. Find out what causes tummy trouble in this article for kids. Read More Indigestion Got tummy troubles? Indigestion is a common condition that many people - even kids - have at one time or another. Find out more in this article for kids. Read More Your Digestive System The digestive system breaks down the food you eat. Learn how in this article for kids. Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.