Which symptom is most indicative of croup rather than bronchiolitis?

• A. Inspiratory stridor
• B. Expiratory wheezing
• C. Crackles on auscultation
• D. Productive cough

Answer: (A)

Inspiratory stridor reflects upper airway narrowing, typically from subglottic edema seen in croup. This occurs as air is drawn through an inflamed, constricted segment high in the airway, producing a harsh, audible sound on inhalation. Bronchiolitis, by contrast, involves the lower airways and usually presents with expiratory wheezing and diffuse crackles from mucus and inflammation in the small bronchioles. A productive cough is less characteristic of croup and more common with lower airway infections. So the presence of inspiratory stridor best points to croup.