Most inhaled objects are not radio-opaque: the sign is air trapping — a hyperlucent lung that stays inflated on expiration or on the dependent decubitus view — and a normal radiograph does not exclude it; bronchoscopy does.
Orient first
- Toddlers (1–3 years); nuts and seeds are commonest; right main bronchus more often.
- Ball-valve obstruction causes air trapping; complete obstruction causes collapse.
- Low-dose CT can show the object and guide bronchoscopy when the radiograph is equivocal.
Acquire the study
- Inspiratory and expiratory frontal views; bilateral decubitus views if the child cannot cooperate.
The manoeuvre
- Radio-opaque object: its site on two views.
- Inspiratory vs expiratory: the affected lung stays hyperlucent and the mediastinum shifts away on expiration.
- Decubitus: the dependent lung should lose volume — if it does not, air trapping.
- Collapse or consolidation distal to the obstruction.
What confirms it
- Bronchoscopic retrieval.
What licenses you to exclude it
- Imaging cannot exclude an inhaled foreign body — a convincing history needs bronchoscopy.
The classic misread
- A normal radiograph (in a large minority) reassuring the team.