From the Guidelines
Initial investigations for a patient with low back pain and fever should include a complete blood count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), blood cultures (at least two sets), urinalysis with culture, and plain radiographs of the lumbar spine, as well as magnetic resonance imaging (MRI) of the spine, which is the gold standard imaging modality for detecting early signs of discitis, osteomyelitis, epidural abscess, or other infectious processes 1.
Key Investigations
- Complete blood count
- Erythrocyte sedimentation rate (ESR)
- C-reactive protein (CRP)
- Blood cultures (at least two sets)
- Urinalysis with culture
- Plain radiographs of the lumbar spine
- Magnetic resonance imaging (MRI) of the spine
Rationale
The combination of fever with back pain raises significant concern for potentially serious infections such as vertebral osteomyelitis, discitis, epidural abscess, or pyelonephritis, which require prompt diagnosis and treatment 1. Early identification of the infectious source is crucial as delayed treatment of spinal infections can lead to neurological complications, sepsis, and increased mortality.
Additional Considerations
Depending on clinical suspicion, further testing may include a tuberculin skin test or interferon-gamma release assay if tuberculosis is suspected. Image-guided aspiration biopsy of the affected area should be performed when possible before starting antibiotics to identify the causative organism 1. If MRI is unavailable, computed tomography (CT) can be considered though it is less sensitive for early infection 1.
From the Research
Initial Investigations for Low Back Pain and Fever (LPFB)
The initial investigations for a patient with Low Back Pain and Fever (LPFB) may include:
- Complete Blood Count (CBC) to check for signs of infection or inflammation 2
- Erythrocyte Sedimentation Rate (ESR) to monitor chronic inflammatory conditions 3, 4, 5
- C-reactive protein (CRP) to diagnose and monitor acute inflammatory conditions 3, 4, 5
- Lumbar spine magnetic resonance images to evaluate lumbar intervertebral disc degeneration and vertebral end-plates 2
- Blood cultures to check for bacterial infections
- Urine analysis to check for urinary tract infections
Inflammatory Markers
Inflammatory markers such as ESR and CRP can be used to differentiate between acute and chronic medical conditions 5.
- Elevated ESR is seen more frequently in acute medical conditions as compared to CRP 5
- Both ESR and CRP have a positive association with acute as well as chronic medical conditions 5
Diagnostic Considerations
It is essential to consider the clinical aspects and medical history of the patient when interpreting the results of these investigations 6.