A neonate born at 29 weeks gestation develops tachypnea, expiratory grunting, and cyanosis within hours of birth. Chest radiograph shows diffuse ground glass opacities with air bronchograms. The underlying pathogenesis is deficient production of which substance by type II pneumocytes?

• A Immunoglobulin A
• B Alpha-1 antitrypsin
• C Surfactant phospholipids, mainly dipalmitoyl lecithin ✓
• D Fibronectin

Explanation

Respiratory distress syndrome of the newborn results from inadequate surfactant synthesis by immature type II pneumocytes before 34 weeks of gestation. Surfactant reduces surface tension at the air-fluid interface, so its absence causes widespread alveolar collapse, atelectasis, and formation of hyaline membranes from leaked plasma proteins. Corticosteroids given to mothers prenatally accelerate surfactant production and reduce disease incidence.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.