Soft tissue lateral neck film
Guidelines for children less than 15yo
1. Prevertebral space <7mm anterior to C2
2. Prevertebral space <14mm anterior to C6
3. Prevertebral space <40% of anteroposterior diameter of C3 or C4 vertebral bodies.
4. Neck flexion can cause false positive results
5. CT w/ IV contrast very sensitive for RPA and will be better definition of airway impingement and involvement of local structures.