"USMLE STEP 1 Reality" by Dr Brian Bolante

Croup (acute laryngotracheobronchitis) on X-ray with steeple sign

Croup, also called acute laryngotracheobronchitis is caused by viral infection of the upper airway usually parainfluenza virus or respiratory syncytial virus (RSV). It is common and has a peak incidence before the age of 1 year (typically between 3 and 6 months of age).

It is presented Clinically by protracted barking cough and inspiratory stridor due to tracheal narrowing that is caused by mucosal oedema .

X-ray finding :
On Plain film
The diagnosis of acute laryngotracheobronchitis or Croup is usually made clinically
and no need for doing x-ray.you may do it just for excluding other causes of same presentation like:
- foreign body aspiration.........tracheal or oesophageal.
- angioneurotic edema
- epiglottitis and epiglottic-cysts
- congenital subglottic stenosis

However there are some typical radiographic findings :


1- steeple sign (the image above): seen on AP radiographs of the neck or chest and neck demonstrates uniform narrowing of the subglottic airway

But What is steeple sign ??
The steeple sign refers to superior tapering of the trachea on a frontal chest radiograph. It is remaniscient of a church steeple and is suggestive of croup.


2- distension of the hypopharynx is also seen due to the patient's attempt at decreasing airway resistance (the image below)

What is the USMLE?

USMLE represents The United States Medical Licensing Examination,it is a three-part licensing examination that is required in order to receive a license to practice medicine within the United States.
This exam is designed by the Federation of State Medical Boards and the National Board of Medical Examiners to determine whether or not an individual understands and can apply the knowledge necessary to practice medicine safely and intelligently. The USMLE is actually comprised of 3 different exams that are referred to as steps, which examine the individual's knowledge of specific topics related to the field of medicine like basic science, medical knowledge, medical skills, clinical science, and the application of all of these skills and areas of knowledge in the medical field.

All three steps of the USMLE include a series of computerized multiple-choice questions (MCQs), but the format of the exam and the information covered in each multiple-choice section is different for each step of the USMLE. The USMLE Step II also has a clinical skills portion that examines an individual's ability to work with real patients and the USMLE Step III has a computerized patient simulation portion in addition to the multiple-choice section of the exam. In order for an individual to receive a license to practice medicine, the individual must pass all three steps of the USMLE.

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