Chest X-Ray Findings in Meconium Aspiration Syndrome
The correct answer is B: Patchy infiltrates with areas of hyperinflation and atelectasis is the characteristic chest X-ray finding in meconium aspiration syndrome. 1
Radiographic Features of MAS
The classic chest X-ray pattern in meconium aspiration syndrome demonstrates:
- Patchy infiltrates (opacifications) combined with hyperinflation, which reflects the dual pathophysiology of partial and complete airway obstruction by meconium 2
- Areas of atelectasis that occur due to complete airway obstruction by meconium plugs and surfactant inactivation 1
- Hyperinflation resulting from ball-valve obstruction where meconium allows air entry but prevents complete exhalation 2
The radiographic pattern correlates with ultrasound findings showing B-pattern (interstitial), consolidations, atelectasis, and bronchograms that vary with time as meconium redistributes in the lungs 1
Why Other Options Are Incorrect
Option A: Ground-Glass Appearance with Air Bronchograms
- This finding is characteristic of respiratory distress syndrome (RDS), not MAS 1
- RDS occurs primarily in premature infants (<1,500 g birth weight), whereas MAS occurs in term and post-term infants 1
- The pathophysiology is completely different: RDS involves surfactant deficiency in premature lungs, while MAS involves mechanical obstruction and chemical pneumonitis 1
Option C: Diffuse Bilateral Opacities with Air Bronchograms
- This pattern lacks the characteristic hyperinflation that is pathognomonic for MAS 2
- While consolidations and air bronchograms can be seen in MAS, the absence of hyperinflation makes this description incomplete and more suggestive of other conditions 1, 3
Option D: Normal Lung Fields
- By definition, MAS presents with respiratory distress and radiographic abnormalities 2
- Normal chest X-ray would exclude the diagnosis of MAS 2
Clinical Context
MAS typically presents in term and near-term infants delivered through meconium-stained amniotic fluid with early onset respiratory distress, poor lung compliance, and hypoxemia 2. The characteristic radiographic pattern of patchy infiltrates with hyperinflation and atelectasis directly reflects the underlying pathophysiology of partial airway obstruction (causing hyperinflation), complete obstruction (causing atelectasis), and chemical pneumonitis (causing infiltrates) 1, 2.