What imaging studies are recommended for a patient with a suspected foreign body in the airway?

Imaging for Suspected Airway Foreign Body

For suspected airway foreign body, obtain chest radiography (anteroposterior and lateral views) as the initial screening study, but proceed directly to bronchoscopy based on clinical suspicion regardless of imaging results, as radiographs have poor sensitivity (33-73%) and should never delay definitive diagnosis. 1, 2, 3

Initial Imaging Protocol

• Chest radiography (AP and lateral views) is the first-line imaging modality to assess for radiopaque foreign bodies, air trapping, atelectasis, pneumonia, or pneumomediastinum 4, 1, 2
• Plain radiographs detect only 33-73% of airway foreign bodies, with false-negative rates up to 47% for esophageal foreign bodies and up to 85% for non-radiopaque objects (food, wood, plastic, fish bones) 4, 1, 2
• Adding expiratory or decubitus views increases false positives without improving true positive detection and lacks clinical benefit 5

When to Proceed to CT Imaging

• CT chest without IV contrast should be obtained when radiographs are negative but clinical suspicion remains high, with sensitivity of 90-100% and specificity of 93.7-100% 1, 6, 7
• CT with airway reconstruction has the highest diagnostic accuracy and can eliminate unnecessary bronchoscopy when negative, particularly for detecting non-radiopaque foreign bodies 7
• CT is superior to plain films for identifying complications including perforation, abscess, mediastinitis, and pneumomediastinum 4

Critical Decision Point: When Imaging Should NOT Delay Intervention

Proceed directly to emergency bronchoscopy WITHOUT waiting for imaging if the patient has: 1

• Complete airway obstruction
• Severe stridor or acute respiratory distress
• Inability to manage secretions
• Hemodynamically unstable

The Bronchoscopy Imperative

• Rigid bronchoscopy should be performed in ALL patients with suspected foreign body aspiration based on history and physical examination, regardless of imaging findings 4, 1, 3
• The decision for bronchoscopy is based on clinical presentation (witnessed aspiration event, choking, wheezing, decreased breath sounds, persistent cough, localized wheeze) and should not be altered by negative radiographic studies 2, 3
• Bronchoscopy serves both diagnostic and therapeutic purposes, with successful foreign body retrieval in approximately 79% of cases 3

Common Clinical Presentations Requiring Imaging Workup

• Witnessed aspiration event with respiratory symptoms (most common) 2
• Persistent or recurrent wheezing unresponsive to bronchodilators 4
• Localized hyperinflation, atelectasis, or recurrent pneumonia on imaging 4
• Chronic cough with normal initial workup 4
• Hemoptysis with dysphonia (suggests laryngeal/tracheal foreign body requiring urgent visualization) 1

Key Pitfalls to Avoid

• Never rely on negative chest radiographs to exclude airway foreign body - sensitivity is only 33-73% and specificity 45-79% 2, 5
• Do not delay bronchoscopy to obtain CT imaging in unstable patients or those with high clinical suspicion 1, 2
• Do not trust the patient's reported location of foreign body sensation, as correlation with actual location is poor (kappa 0.27) 1
• Avoid contrast-enhanced CT as initial study, as contrast may obscure foreign body identification 6
• Do not order MRI before excluding metallic foreign bodies, due to risk of heating and motion artifacts 1, 6

Age-Specific Considerations

• Children under 5 years (especially 2-3 years) are at highest risk, with 70% of cases occurring in this age group 3
• Vegetables and small plastic toy parts (especially whistles) are the most commonly aspirated objects in children 3
• In pediatric patients with negative CT with airway reconstruction, symptoms typically resolve without need for bronchoscopy 7