[Acute abdomen].

Acute abdomen is not a disease entity on its own but describes a critical state of the patient which can be caused by numerous diseases. The surgeon and internist have to apply an interdisciplinary approach to enable a rapid decision on whether immediate laparotomy is mandatory. Few appropriate diagnostic procedures support decision making. In many cases there is an indication for immediate surgery, such as perforated gastric or duodenal ulcer, acute appendicitis, diverticulitis, ruptured aortic aneurysm, mechanic ileus, infarction of the mesenteric artery. This review is mainly focused on diseases which may present as acute abdomen but for which surgery is usually not indicated, such as acute pancreatitis. Furthermore, one also has to consider rare diseases in which laparotomy would clearly be a mistake, such as acute intermittent porphyria or intestinal pseudo-obstruction.