What are the primary differential diagnoses for a child presenting with symptoms of croup?

Differential Diagnoses for Croup

The primary differential diagnoses for a child presenting with croup-like symptoms include bacterial tracheitis, epiglottitis, foreign body aspiration, peritonsillar abscess, retropharyngeal abscess, and angioedema. 1, 2

Key Clinical Differentiators

Bacterial Tracheitis

• Consider when: Child appears toxic with high fever, progressive respiratory distress despite standard croup treatment, and purulent secretions 1, 3
• More likely complication when croup is caused by influenza virus rather than parainfluenza 3
• Requires immediate recognition as it represents a life-threatening bacterial superinfection 1

Epiglottitis

• Consider when: Sudden onset of respiratory distress with drooling, inability to swallow, toxic appearance, and preference for sitting upright (tripod position) 2, 4, 5
• Typically presents WITHOUT the barking cough characteristic of croup 4
• Critical pitfall: Do not attempt to visualize the airway or perform blind finger sweeps, as this may precipitate complete airway obstruction 1

Foreign Body Aspiration

• Consider when: Sudden onset of respiratory distress with coughing, gagging, stridor, or wheezing WITHOUT fever or antecedent upper respiratory symptoms 1
• History may reveal choking episode or witnessed aspiration 2, 6
• Critical pitfall: Blind finger sweeps should never be performed as they may push the object further into the pharynx 1
• Lateral neck radiographs are often unreliable; clinical assessment takes priority 1

Peritonsillar and Retropharyngeal Abscess

• Consider when: Severe throat pain, dysphagia, drooling, muffled voice, and neck stiffness or swelling 2, 4
• Fever typically higher than in viral croup 4
• May present with unilateral tonsillar swelling or neck mass 2

Angioedema

• Consider when: Rapid onset of airway swelling without infectious prodrome 2
• History of allergic triggers, medication exposure (ACE inhibitors), or hereditary angioedema 2
• Absence of fever and barking cough 2

Distinguishing Features of Viral Croup

To differentiate true viral croup from these conditions, look for:

• Typical presentation: Low-grade fever, barking/seal-like cough, inspiratory stridor, and preceding upper respiratory symptoms for 1-2 days 2, 4, 5
• Viral etiology: Most commonly parainfluenza viruses (types 1-3), but also RSV, rhinoviruses, coronaviruses, adenoviruses, influenza, and human metapneumovirus 7, 3
• Age range: Most common in children 6 months to 6 years of age 4, 5
• Seasonal pattern: Typically late fall or early winter 4

When to Pursue Alternative Diagnoses

Red flags requiring immediate consideration of alternative diagnoses:

• Toxic appearance or high fever (>39°C) 1, 4
• Drooling or inability to swallow 2, 4
• Rapid progression despite appropriate croup treatment 1
• Absence of barking cough 4
• Sudden onset without viral prodrome (except spasmodic croup) 8
• Oxygen saturation <92-94% despite oxygen therapy 1
• Stridor at rest with severe respiratory distress requiring >3 doses of racemic epinephrine 1

Radiographic studies should be avoided unless there is concern for an alternative diagnosis, as they are generally unnecessary for typical croup. 1