What are the next steps for a patient with intermittent lower back and lower right quadrant pain and a recent fever?

Immediate Diagnostic Workup for Suspected Vertebral Osteomyelitis or Appendicitis

This patient requires urgent spine MRI and blood cultures to rule out vertebral osteomyelitis, given the combination of fever and lower back pain, which represents a potentially serious infection that can lead to permanent spinal cord injury if diagnosis is delayed. 1

Critical Red Flag Assessment

The combination of fever with new or worsening back pain is a strong indicator for vertebral osteomyelitis (NVO), a serious condition where diagnostic delays can result in permanent neurologic damage or septicemia. 1 The Infectious Diseases Society of America specifically identifies this presentation as requiring immediate investigation. 1

Key Diagnostic Steps

Immediate laboratory workup:

• Obtain 2 sets of aerobic and anaerobic blood cultures before any antibiotics 1
• Measure baseline ESR and CRP, as elevated inflammatory markers combined with back pain further support NVO diagnosis 1
• Check complete blood count for leukocytosis 1

Imaging priority:

• Spine MRI is the recommended first-line imaging study for suspected NVO 1
• If MRI cannot be obtained (due to implantable cardiac devices, claustrophobia, or unavailability), proceed with combination spine gallium/Tc99 bone scan, CT scan, or PET scan 1

Addressing the Right Lower Quadrant Pain Component

While vertebral osteomyelitis must be ruled out first given its serious implications, the right lower quadrant (RLQ) pain component requires simultaneous evaluation:

For RLQ pain with fever and leukocytosis:

• CT abdomen and pelvis with IV contrast is the first-line imaging modality if appendicitis is suspected, with sensitivity of 85.7-100% and specificity of 94.8-100% 1, 2
• This single study can evaluate both appendicitis and identify abdominal sources that might explain the clinical picture 1

Alternative considerations for RLQ pain:

• Perform abdominal ultrasound if there are abdominal symptoms or suspicion of an abdominal source, particularly if recent abdominal surgery occurred 1
• For patients with RLQ pain and fever, a thin-walled fluid collection >3 cm adjacent to the cecum with nonvisualization of the appendix suggests appendiceal abscess requiring percutaneous catheter drainage 1

Clinical Decision Algorithm

Step 1: Assess neurologic status

• Perform pertinent motor and sensory neurologic examination 1
• Percussion of the spine to identify focal tenderness 1
• Any new neurologic symptoms with fever warrant immediate NVO investigation 1

Step 2: Risk stratification for NVO High-risk features include:

• Recent Staphylococcus aureus bloodstream infection in the previous year 1
• Immunocompromised state, active IV drug use, indwelling central catheters, or recent instrumentation 1
• Residence in areas endemic for tuberculosis or brucellosis 1

Step 3: Simultaneous imaging approach

• Order spine MRI for back pain evaluation 1
• Order CT abdomen/pelvis with IV contrast for RLQ pain evaluation 1, 2
• Both studies can be performed concurrently to avoid diagnostic delay

Critical Pitfalls to Avoid

Do not delay imaging waiting for inflammatory markers: While ESR and CRP should be obtained, fever is only present in up to 45% of bacterial NVO cases, and normal inflammatory markers do not exclude the diagnosis. 1

Do not assume simple musculoskeletal back pain: The average time to diagnosis of NVO is 2-4 months, and 34% of patients are initially misdiagnosed. 1 The presence of fever transforms this from routine back pain to a medical emergency.

Do not perform plain radiographs as initial imaging: Lumbar spine radiography should be delayed for at least 1-2 months in nonspecific pain without red flags 3, and it provides no useful information for acute infection evaluation.

Do not start empiric antibiotics before obtaining blood cultures: Blood cultures must be drawn before antimicrobial therapy, as they are positive in a significant proportion of NVO cases and guide definitive treatment. 1

Specialist Consultation

Evaluation by an infectious disease specialist and spine surgeon should be considered for patients with suspected NVO to ensure appropriate management and prevent complications. 1