Acquired subglottic stenosis is most often caused by:

• A. Prolonged endotracheal intubation
• B. Frequent suctioning
• C. Oxygen therapy
• D. Tracheostomy

Answer: (A)

Subglottic stenosis develops when the mucosa in the subglottic region is injured and healing scar tissue narrows the airway. In newborns, this area is already the narrowest part of the airway, so injury there is particularly impactful. The most common trigger for this injury is prolonged endotracheal intubation. The continuous pressure of the tube and its cuff against the subglottic mucosa causes ischemia, inflammation, and granulation tissue, which matures into scar formation that reduces the airway diameter.

Frequent suctioning can irritate mucosa but does not typically produce the fixing, scar-based narrowing seen with long-term tube contact. Oxygen therapy alone does not cause structural subglottic injury. Tracheostomy can be associated with airway changes, but the pattern and frequency of acquired subglottic stenosis are most strongly linked to prolonged endotracheal intubation in neonates.