Steeple sign

Overview
In radiology, the steeple sign is a sign on a frontal X-ray of tracheal narrowing and suggestive of the diagnosis of croup.

Plain film

 * Steeple sign is seen on anteroposterior radiographs of the soft tissues of the neck.
 * Normal lateral convexities of the subglottic trachea are lost, and narrowing of the subglottic lumen produces an inverted V configuration in this area.
 * Point of the inverted V is at the level of the inferior margin of the true vocal cords.
 * Narrowing of the subglottic lumen alters the radiographic appearance of the tracheal air column, which resembles a steeply pitched roof or a church steeple.
 * The lateral radiograph of the upper airway will show a normal epiglottis and narrowing of the subglottic region.