On the anteroposterior or AP view there is distention of the hypopharynx with symmetric subglottic narrowing in the first 1-2 cm of the trachea. This is also known as the steeple sign because it resembles a church spire. The lateral view may show subglottic narrowing or loss of the air shadow. The complete blood count or CBC is generally unremarkable except for a lymphocytosis. Bronchoscopy would show mild subglottic edema.
Treatment depends on the severity of the disease.
Either way, the first principle is to provide humidification by a cool-mist humidifier or other means. In cooler weather or at night, taking the child outside may break the acute episode alone. The child should also receive adequate fluid either orally or intravenously. If hospitalized, monitoring for hypoxia is important. Pulse oximetry or arterial blood gas analysis also known as ABG can be used.