In patients with blunt abdominal trauma, trauma mechanism, physical examination and radiological examinations give information about possible injuries. This case report describes a trauma patient with upper abdominal complaints, a seatbelt sign and abdominal and retroperitoneal free air seen on computed tomography. Duodenal and pancreatic injury is suspected, however laparotomy showed sigmoid perforation. The differences between preoperative findings and final diagnosis are discussed. Moreover, limitations of radiological examinations in trauma patients are discussed and it is emphasized that a critical appraisal of diagnostic information is necessary before treatment is started.