The appendix is a small finger-like appendage that's attached to the far end of the colon. Generally, for unknown reasons, it can become infected or its opening obstructed. Usually the pain of appendicitis begins around the bellybutton and migrates to the right lower abdomen, and is accompanied by a low fever (100 to 101 degrees), poor appetite, mild diarrhea, and sometimes vomiting. The abdomen is often so tender to the touch even a gentle shaking of the bed a child is lying on can hurt.
If your child shows these symptoms, see your pediatrician or head for the emergency room. Once appendicitis is diagnosed -- typically through a combination of X ray, ultrasound and blood tests -- the inflamed organ is surgically removed. Otherwise there's a risk it will rupture, and the contents of the colon will spill out into the abdominal region.