Abdominal pain is the chief complaint in about 4% of primary care visits and 5% of emergency room (ER) visits. In 10% of those visits, surgery is required. Missed appendicitis is 1 of the top 10 conditions that lead to malpractice claims. Among ER physicians, it is in the top 5. On the other hand, about 20% of patients taken to surgery for presumed appendicitis do not have it.There is no easy way to diagnose appendicitis, which can masquerade as a number of more benign conditions, including gastroenteritis, gastritis, urinary tract infection (UTI), and constipation. The differential for acute abdominal pain also includes pelvic inflammatory disease (PID), small bowel obstruction, abdominal aortic aneurysm, mesenteric ischemia, myocardial infarction with atypical presentation, perforated viscus, cholecystitis, nephrolithiasis, and ectopic pregnancy.