Rationale: Abdominal pain has an extremely broad differential diagnosis list. Certain features often help in determining which is the most likely etiology. Lower-right quadrant pain suggests appendicitis, whereas upper-right quadrant pain is suggestive of cholecystitis or cholelithiasis. The absence of diarrhea or emesis makes gastroenteritis and Crohn disease unlikely. Esophagitis or reflux disease would likely have chest pain as a prominent symptom. Pain associated with signs of acid hypersecretion suggests peptic ulcer disease. However, these are generalizations, and other factors, such as lab results and endoscopy, must also be considered.