- Infection (croup, bacterial tracheitis, epiglottitis, retropharyngeal abscess)
- Foreign body (airway, esophagus)
- False positives due to expiration / flexion
Approach to the differential diagnosis of acute upper airway obstruction:
- By age: if < 6 months old think congenital cause, if 12 months old think croup, if > 3 years old think bacterial tracheitis / airway foreign body / epiglottitis
- Infection
- Croup is a glottic + subglottic process with a steeple sign
- Bacterial tracheitis is a glottic + subglottic process with an indistinct trachea containing plaques
- Epiglottitis is a supraglottic process with an enlarged epiglottis + aryepiglottic folds
- Retropharyngeal abscess is diagnosed when there is soft tissue thickening of > 1 cervical vertebral body
- Foreign body
- Airway foreign bodies cause air trapping which is best seen on expiratory or decubitus CXR
- Esophageal foreign bodies can cause surrounding edema leading to tracheal narrowing
- Beware of false positives due to lateral airway images obtained in expiration / flexion
Pediatric Imaging 