2019 ACR Appropriateness Criteria®: Rib Fractures

1. Basic Information

2. Core Imaging Recommendations by Clinical Scenario

2.1 Isolated Minor Blunt Trauma (Low-Risk, No Red Flags)

• Usually Appropriate (7–9):
  • Chest radiography (CXR): PA + lateral (initial, sufficient for most; detects >80% of rib fractures + life-threatening complications)PubMed
   
• May Be Appropriate (4–6):
  • Chest CT (with/without contrast): If CXR normal but high clinical suspicion for occult fracture/complication (e.g., persistent severe pain, dyspnea)
   
• Usually Not Appropriate (1–3):
  • MRI, Tc-99m bone scan, ultrasound, rib-specific radiographs (oblique views add little value, increase radiation/ cost)
   

2.2 Major Blunt Trauma (High-Risk, Multiple Fractures/Flail Chest/Comorbidities)

• Usually Appropriate (7–9):
  • Chest CT (with contrast, if hemodynamically stable): Gold standard for detecting rib fractures (including occult), flail chest, pneumothorax, hemothorax, pulmonary contusion, aortic injury, and other thoracic/abdominal injuries
  • CXR: Initial screening (rapid, portable for unstable patients) before CT
   
• May Be Appropriate (4–6):
  • Ultrasound (for rapid detection of pneumothorax in unstable trauma)
   
• Usually Not Appropriate (1–3):
  • Tc-99m bone scan, MRI (delay diagnosis, no added benefit for acute trauma)
   

2.3 CPR-Related Rib Fractures

• Usually Appropriate (7–9):
  • CXR: Initial imaging (detects anterior rib fractures + complications; sufficient for most)PubMed
   
• May Be Appropriate (4–6):
  • Chest CT (if CXR normal but clinical concern for occult fracture/complication)
   
• Usually Not Appropriate (1–3):
  • Tc-99m bone scan, MRI, ultrasound
   

2.4 Suspected Pathologic Rib Fractures (No Trauma, Metastasis/Myeloma/Osteoporosis)

• Usually Appropriate (7–9):
  • Chest CT (with contrast): Detects lytic/blastic lesions, soft-tissue masses, and underlying malignancy
  • Tc-99m bone scan: Whole-body screening for multifocal pathologic fractures (complementary to CT)
  • CXR: Initial screening (low sensitivity for subtle pathologic fractures)
   
• May Be Appropriate (4–6):
  • MRI (for spinal cord/nerve root involvement, soft-tissue extension)
   
• Usually Not Appropriate (1–3):
  • Ultrasound
   

3. Key Clinical Principles & Caveats

1. Fracture vs. Complication Priority: Isolated rib fractures are low-morbidity; imaging focus is on detecting life-threatening complications (pneumothorax, hemothorax, aortic injury, pulmonary contusion) rather than just counting fracturesPubMed.
2. CXR Limitations: Misses ~15–20% of rib fractures (especially posterior/occult); normal CXR does not rule out rib fracture in symptomatic patients.
3. CT Considerations:
   • Indicated for major trauma, flail chest, persistent severe pain, or CXR with suspicious findings.
   • Avoid in hemodynamically unstable patients (prioritize resuscitation + portable CXR).
   • Low-dose CT protocols reduce radiation exposure while maintaining diagnostic accuracy.
    
4. Bone Scan Role: Reserved for occult/pathologic fractures (not acute blunt trauma); delayed imaging (2–4 hours post-injection) improves sensitivity.
5. MRI Role: Rarely used for acute rib fractures; indicated for suspected spinal cord injury, soft-tissue infection, or tumor extension.
6. Ultrasound Role: Limited to rapid pneumothorax detection in unstable trauma; not for routine rib fracture evaluation.

4. Clinical Decision Tree (Simplified)

1. Minor blunt trauma + no red flags → CXR (PA + lateral) → If normal + symptomatic: consider CT (may be appropriate)
2. Major blunt trauma + red flags (flail chest, dyspnea, hypotension, multiple fractures) → CXR (portable) → Chest CT (with contrast) (stable patients)
3. CPR-related fractures → CXR → If normal + symptomatic: consider CT
4. Suspected pathologic fractures → CXR → Chest CT + Tc-99m bone scan

5. Red Flags for Urgent CT/Trauma Activation

• Flail chest (≥3 consecutive rib fractures in 2+ places)
• Hypotension, tachycardia, respiratory distress
• Pneumothorax/hemothorax on CXR
• Severe persistent pain (VAS ≥7) despite analgesia
• Suspicion of aortic injury (widened mediastinum on CXR)
• Multiple rib fractures (≥3) in elderly/frail patients (high complication risk)

6. Clinical Quick Reference Card