Bronchiolitis vs Croup
How to tell Bronchiolitis and Croup apart when a board question makes them look alike.
Step 2 CK pairs are in open beta while clinical review finishes. Spot an issue? Tell us.
Inspiratory stridor with a barky cough identifies croup rather than bronchiolitis.
Side by side
Infant younger than 2 years with viral prodrome followed by diffuse wheeze, crackles, tachypnea, and retractions from lower airway inflammation.
Toddler with barky cough and inspiratory stridor from subglottic upper airway edema, often worse at night.
RSV and similar viruses cause edema and mucus plugging of small bronchioles, raising lower airway resistance.
Parainfluenza and related viruses inflame the larynx and subglottic trachea, narrowing upper airway lumen.
Diagnosis is clinical; oxygen saturation below 90% to 92% or significant work of breathing guides admission, and chest x-ray is usually unnecessary unless atypical course.
Diagnosis is clinical; moderate to severe croup with stridor at rest warrants dexamethasone 0.6 mg/kg and nebulized racemic epinephrine, with observation for rebound symptoms.
The trap
Both illnesses follow upper respiratory symptoms, so wheezy infants are sometimes treated like croup with upper-airway-only therapy or given unnecessary bronchodilators repeatedly. The resolving clue is noise location: stridor localizes to upper airway croup, while diffuse wheeze and crackles with feeding difficulty localize to bronchiolitis where supportive care and oxygen are primary.
The repair move
Next best step: give dexamethasone 0.6 mg/kg orally or intramuscularly for croup of any severity, and add nebulized racemic epinephrine for stridor at rest with close observation for at least 2 to 3 hours. For bronchiolitis, prioritize suctioning, hydration, and supplemental oxygen when saturation drops below target rather than routine steroid or antibiotic therapy.
Try a free question
CoreA 22-month-old girl has barky cough and inspiratory stridor at rest. BP 92/56 mm Hg, HR 146/min, temp 37.9 C, oxygen saturation 94%. What is the next best step in management?
Show answer and explanation
Answer: A. Nebulized racemic epinephrine plus dexamethasone. Stridor at rest indicates at least moderate croup, so dexamethasone with racemic epinephrine is indicated.
Why the other choices are tempting
- B. Wrong. Typical croup is viral and not treated with routine antibiotics.
- C. Wrong. Albuterol does not reliably relieve subglottic edema.
- D. Wrong. Imaging is unnecessary in classic croup without red flags for alternative diagnosis.
- E. Wrong. Symptomatic stridor at rest warrants active treatment.
Flashcards
Tap a card to flip it.
Which breath sound most strongly favors croup over bronchiolitis?
Inspiratory stridor, especially with barky cough, favors croup.
What exam pattern is classic for bronchiolitis in infants?
Diffuse wheeze and crackles with tachypnea and retractions after viral prodrome is classic bronchiolitis.
Quick answers
What is the fastest way to tell Bronchiolitis from Croup?
Inspiratory stridor with a barky cough identifies croup rather than bronchiolitis.
What is the key clue for Bronchiolitis?
Infant younger than 2 years with viral prodrome followed by diffuse wheeze, crackles, tachypnea, and retractions from lower airway inflammation.
What is the key clue for Croup?
Toddler with barky cough and inspiratory stridor from subglottic upper airway edema, often worse at night.
What is the common trap with Bronchiolitis vs Croup?
Both illnesses follow upper respiratory symptoms, so wheezy infants are sometimes treated like croup with upper-airway-only therapy or given unnecessary bronchodilators repeatedly. The resolving clue is noise location: stridor localizes to upper airway croup, while diffuse wheeze and crackles with feeding difficulty localize to bronchiolitis where supportive care and oxygen are primary.