A term neonate delivered by elective cesarean section at 38 weeks develops tachypnea of 90 per minute at 1 hour of life with mild retractions and a normal radiograph showing prominent perihilar vascular markings. Symptoms resolve by 36 hours. The mechanism is:
- A Surfactant deficiency from type II pneumocyte immaturity
- B Persistent elevation of pulmonary vascular resistance with right-to-left shunting
- C Delayed resorption of fetal lung fluid through epithelial sodium channels ✓
- D Aspiration of infected amniotic fluid causing chemical pneumonitis
Correct answer: C. Delayed resorption of fetal lung fluid through epithelial sodium channels
Explanation
Transient tachypnea of the newborn results from delayed clearance of the 20 to 30 mL/kg of lung fluid present at birth. Labor surges catecholamines that upregulate epithelial sodium channel activity, driving fluid out; cesarean delivery without labor bypasses this surge. Radiograph shows fluid in fissures and perihilar streaking, and resolution is spontaneous within 72 hours. Surfactant deficiency produces ground-glass appearance instead.
Reference: Nelson Textbook of Pediatrics, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.