Croup is mega high-yield for your pediatric shelf exam and for Step 1 and Step 2, as it integrates microbiology, immunology, and clinical skills. This is a common fall-and-winter viral infection in kids ages 6 months to 3 years and is usually caused by PARAINFLUENZA. It starts with mild-cold symptoms before progressing to the classic seal-bark cough, hoarse voice, and INSPIRATORY stridor. Severe cases show stridor at rest, retractions, and hypoxemia. Diagnosis is clinical, but X-Ray will show a