ZyraDoc #57 - September 27, 2026

A 14-month-old male infant is brought to the emergency department with a 2-day history of low-grade fever, nasal congestion, hoarseness, and a harsh, seal-like barking cough that acutely worsened during the night.

On physical examination, he is distressed and agitated, exhibiting inspiratory stridor at rest, suprasternal and intercostal retractions, and an oxygen saturation of 93% on room air.

An anteroposterior neck radiograph demonstrates subglottic tracheal narrowing (the classic 'steeple sign'), establishing a diagnosis of Croup (Acute Laryngotracheobronchitis).

Case Summary

Clinical Focus:

The diagnosis is Croup (Acute Laryngotracheobronchitis) with moderate-to-severe upper airway obstruction.

Aetiology/Cause:

Viral infection of the upper respiratory tract, most commonly caused by Human Parainfluenza Virus (Type 1 and Type 2).
Other viral causes include Respiratory Syncytial Virus (RSV), Influenza, Adenovirus, and Enterovirus.
Infection leads to inflammatory edema and swelling of the subglottic mucosa, narrowing the larynx and trachea.

Clinical Features:

Classic triad: harsh barking seal-like cough, hoarse voice/cry, and inspiratory stridor.
Subcostal, intercostal, and suprasternal retractions indicating respiratory distress.
Symptoms typically worsen at night and increase with agitation or crying.

Diagnosis and Investigations:

You've already played this ZyraDoc! Try out others from the Archives, or come back tomorrow for a new one!

Incorrect!

Correct!

Please pick from the selection list or skip

1/3.

✗

2/3.

✗

3/3.

✗

What's the Best Next Step?

Case Summary

Reset Password

Verify Your Account

Verify Your Account