Red flags The following findings are of particular concern: Abdominal aorta that is > 5 cm (particularly if tender) or lower-extremity pulse deficits Acute, tearing upper and midback pain Cancer, diagnosed or suspected Neurologic deficit Fever or chills Gastrointestinal findings such as localized abdominal tenderness, peritoneal signs, melena, or hematochezia Infection risk factors (eg, immunosuppression; IV drug use; recent surgery, penetrating trauma, or bacterial infection) Meningismus Severe nocturnal or disabling pain Unexplained weight loss Interpretation of findings Although serious extraspinal disorders (eg, cancers, aortic aneurysms, epidural abscesses, osteomyelitis) are uncommon causes of back pain, they are not rare, particularly in high-risk groups.