Clinical History
A 3-year-old boy presented to the emergency department with sudden onset of cough. The patient was otherwise asymptomatic and had been previously well. In a child of this age, the history is
suspicious of foreign body inhalation. A chest radiograph was performed and the patient proceeded to an emergency bronchoscopy.
Imaging Findings
The initial chest radiograph revealed shift of the heart and mediastinal structures to the right side. The left lung was overinflated, and there was narrowing and irregularity of the lumen of the
left mainstem bronchus. The imaging appearances are consistent with FB aspiration. The child proceeded immediately to the operating theatre, where he underwent a flexible bronchoscopy. Several peanut
fragments were removed from the left mainstem bronchus. A post-bronchoscopy chest radiograph showed lung volumes to have equalised, and the heart and mediastinum to be centrally placed. The lumen of
the left mainstem bronchus remained somewhat narrowed.
Discussion
Inhalation of a FB most commonly occurs in children less than 4 years of age, when they have a tendency to explore things with their mouths. Food particles and organic materials constitute the vast
majority of aspirated objects; they elicit an intense inflammatory response, which exacerbates the degree of airway narrowing. The aspiration may not be witnessed, and the acute symptoms of cough and
wheeze can then go on to become chronic. The FB usually gets lodged in one of the mainstem bronchi. The incidence of right- and left-sided bronchial FBs is almost equal in children, as opposed to the
predominance of right-sided bronchial tree FBs in adults. This is due to the more equal angles with which the main bronchi arise from the trachea in children (in adults, the right mainstem bronchus
has a more vertical course than the left). FBs may cause partial or intermittent airway obstruction, leading to air-trapping through a “ball-valve effect” and to lung or lobar
hyperinflation (depending upon where the object lies). Complete obstruction of the airway lumen can cause lung or lobar collapse. Paired inspiratory and expiratory chest radiographs are helpful to
aid in the diagnosis of aspirated FBs, though they require a degree of patient co-operation. A static lung volume at different phases of respiration is highly suggestive of the presence of an
ipsilateral foreign body. Lateral decubitus radiographs, one on each side, can be diagnostic if the inspiratory-expiratory radiographs cannot be obtained. An unobstructed dependent lung shows smaller
volume and crowded vessels as a result of gravitational forces on the abdominal and mediastinal organs (mimicking lung expiration). In cases of partial luminal obstruction, the dependent lung does
not deflate as expected. It is this relative hyperinflation of the dependent lung that indicates the presence of partial airway occlusion. Other plain radiographic findings associated with FB
inhalation include: pneumomediastinum, pneumothorax, lung consolidation (when secondary infection supervenes) and oligaemia. About 25% of patients have a normal chest radiograph. Other imaging
techniques to diagnose aspirated FBs include the use of fluoroscopy: screening of the chest may reveal a decrease in or absence of diaphragmatic movement on the affected side. CT is the most
sensitive diagnostic imaging tool, but its use is reserved for elusive cases, with the radiation risks of the exam being weighed against the clinical suspicion of an inhaled FB, despite a normal
chest radiograph. Complications of FB aspiration may be immediate or develop over time. Fatal asphyxia is extremely rare, occurring when there is complete obstruction of the airway. Long term
complications include: recurrent pneumonia, broncho-pleural or bronchial fistulae, bronchiectasis and lung abscesses.
Differential Diagnosis List
Foreign body in Left Main Bronchus
Final Diagnosis
Foreign body in Left Main Bronchus
