Meconium aspiration syndrome (MAS)
Chest radiograph shows bilateral coarse reticulogranular opacities with increased lung volumes in a term infant
Meconium aspiration syndrome (MAS)
- Aspiration of meconium into lungs causes three effects
- Airway obstruction
- Atelectasis with partial air trapping and hyperdistention of the alveoli
- May lead to pneumothorax, pneumomediastinum, pneumopericardium
- Surfactant dysfunction
- May cause diffuse atelectasis
- Difficulty ventilating infant
- Chemical pneumonitis
- Diffuse pneumonia occurs rapidly after aspiration
- Airway obstruction
- Complications
- Meconium injury contributes to high pulmonary vascular resistance
- Severe pulmonary hypertension occurs with resultant persistent fetal circulation with right to left shunting across the patent ductus arteriosus
- Difficulty ventilating with air block
- Pneumothorax, pneumomediastinum, pulmonary interstitial emphysema
- Neurologic damage related to anoxic brain injury
- Chronic lung disease after prolonged mechanical ventilation
Imaging findings
Radiography
- Hyperinflated lung volumes
- Rope-like perihilar densities
- Pleural effusion uncommon
- Chest radiograph useful to assess for complications
- Air block and leak phenomena
- Pneumothorax occurs 20-40%
- Pneumomediastinum and pulmonary interstitial emphysema
CT findings
- Occasionally obtained for chronic disease
- Focal areas of lung involvement
- Focal emphysematous changes
- For assessing residual disease
Treatment
Meconium stained distressed infant intubated and suctioned immediately.