1. Lateral (coronal) orientation of coin on PA film. If the coin was in the trachea, we would expect an AP (longitudinal) orientation of the coin secondary to the incomplete rings of the trachea opening posteriorly.
2. Lack of evidence of air trapping or obstruction on both films. (atelectasis, pneumonia, mediastinal shift)
3. Lack of clinical signs of airway compromise. (cough, wheeze, respiratory distress)
4. Location of relatively large object below the level of the larynx.
5. Complete visualization of the intact trachea on the lateral film.