The term “acute abdomen” defines a clinical syndrome characterized by a history of hitherto undiagnosed abdominal pain lasting less than one week. A large range of disorders, from benign, self-limited diseases to conditions that require immediate surgery, can cause acute abdominal pain. Eight conditions account for over 90% of patients who are referred to the hospital and who are seen on surgical wards with acute abdominal pain: acute appendicitis, acute cholecystitis, small bowel obstruction (SBO), urinary colic, perforated peptic ulcer, acute pancreatitis, acute diverticular disease, and non-specific, non-surgical abdominal pain (dyspepsia, constipation).