When to Order X-ray for Back Pain
X-rays of the back are indicated as first-line imaging only when red flags are present on history and physical examination, but should NOT be ordered for uncomplicated back pain without red flags. 1, 2
Do NOT Order X-rays For:
- Uncomplicated acute or chronic low back pain without red flags - most cases are self-limiting and imaging does not improve outcomes 3, 4
- Pain duration less than 4-6 weeks in the absence of red flags - conservative management should be attempted first 3, 4
- Routine screening or patient reassurance alone - studies show X-rays do not reduce worry or provide meaningful reassurance despite patient preference 5, 6
DO Order X-rays When These Red Flags Are Present:
Immediate Red Flags Requiring Imaging:
- Neurologic deficits (motor weakness, sensory changes, saddle anesthesia, bowel/bladder dysfunction) 1, 7, 2
- Fever with back pain - suggests infection (discitis, osteomyelitis, epidural abscess) 1, 7
- History of cancer - best-performing red flag for malignancy 7, 2
- Unintentional weight loss 1, 7
- Night pain that is constant and unrelenting 1, 7
- Tachycardia or lymphadenopathy - suggests systemic infection or malignancy 1, 7
Other Red Flags Warranting X-ray:
- Pain lasting >4 weeks without improvement despite conservative treatment 1, 7, 2
- Morning stiffness - potential inflammatory condition 1, 7
- Gait abnormalities - suggests neurological involvement 1, 7
- Abnormal spinal curvature on examination 1, 7
- Radiating pain with progressive symptoms 1, 2
- Suspected trauma or fracture 3
Critical Limitations of X-rays:
Negative X-rays do NOT exclude serious pathology - they only guide the need for advanced imaging 1, 2. X-rays have only a 9-22% diagnostic yield even when combined with detailed history and physical examination 1.
When X-rays Are Negative But Red Flags Persist:
Proceed immediately to MRI (without contrast for most indications, with and without contrast for suspected infection or malignancy) 1, 7, 2. MRI increases diagnostic yield by 25-34% after negative radiographs 1, 2.
Specific Next Steps After Negative X-rays:
- Urgent MRI without contrast for neurological deficits, suspected cauda equina syndrome, or progressive symptoms 7, 2
- MRI with and without contrast for suspected infection (discitis/osteomyelitis) or malignancy 7, 2
- Bone scan with SPECT/CT for suspected spondylolysis or osseous neoplasm 1, 2
Pediatric Considerations:
The same red flag approach applies to children, with anteroposterior and lateral radiographs as standard first-line imaging 1. Oblique views add little diagnostic value except when specifically evaluating pars interarticularis defects 1.
Common Pitfalls to Avoid:
- Do not order X-rays simply because pain has lasted 6 weeks - red flags must be present 3, 5
- Do not assume X-rays provide reassurance - they increase GP workload without reducing patient worry 5, 6
- Do not delay MRI when neurological deficits are present - X-rays first will delay diagnosis and worsen outcomes 7, 2
- Do not order complete spine imaging when symptoms are localized - targeted imaging of the symptomatic region is sufficient 1, 2