A late preterm infant born at 36 weeks' gestation via elective repeat cesarean delivery without prior labor develops tachypnea (respiratory rate 78 bpm), nasal flaring, and mild intercostal retractions 30 minutes after birth. Pulse oximetry is 93% on room air. Chest radiograph demonstrates prominent perihilar vascular markings, fluid in the interlobar fissures, and mild hyperinflation without focal consolidations. Over the next 24 to 48 hours, the respiratory distress resolves completely with minimal supportive oxygen therapy. What is the diagnosis?

Answer and explanation

Correct answer: C. Transient Tachypnea of the Newborn (TTN)

  1. Step 1: Transient Tachypnea of the Newborn (TTN) is caused by delayed resorption and clearance of fetal alveolar lung fluid.
  2. Step 2: Risk factors include delivery via elective cesarean section without labor (lack of thoracic squeezing and catecholamine-mediated sodium channel activation) and late prematurity.
  3. Step 3: The chest X-ray classically shows perihilar streaking, fluid within the fissures, and symmetric hyperinflation. The condition is self-limiting and typically resolves within 24 to 72 hours with supportive care.
Answer
Transient Tachypnea of the Newborn (TTN).
Why not the others: 'Respiratory Distress Syndrome' is characterized by diffuse ground-glass reticulogranular appearance and air bronchograms due to surfactant deficiency; 'Meconium Aspiration Syndrome' presents with patchy infiltrates and meconium staining; 'Congenital Diaphragmatic Hernia' reveals bowel loops in the hemithorax with a scaphoid abdomen.

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