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diagnostic tools for croup. Radiographs are not necessary, in the evaluation of
routine clinically diagnosed croup. However, anteroposterior and lateral neck
radiographs should be obtained if the diagnosis of croup is in question or if the
child does not respond to therapy as expected. If supraglottitis is strongly
suspected, a lateral neck radiograph should only be obtained in stable and
cooperative patients. Otherwise the child should have their airway secured by the
most senior or skilled clinician prior to other interventions, in the controlled
setting of the operating room whenever possible.
Airway radiographs must be interpreted with care because they are affected by
positioning, crying, swallowing, and the phase of respiration. To properly
interpret the prevertebral space, the lateral neck radiograph must be taken with
the patient’s head extended and during inspiration. Normal tracheal buckling,
which is seen during expiration in a young child, may be misinterpreted as
tracheal mass lesion or deviation from an extrinsic mass ( Fig. 75.2 ). Abnormal
findings on a lateral neck radiograph include a swollen epiglottis or aryepiglottic
folds (supraglottis), irregular tracheal borders or stranding across the trachea
(bacterial tracheitis), and increased prevertebral width (retropharyngeal abscess) (
e-Figs. 75.1 and 75.2 ). In children, the prevertebral space should be less than
the width of the adjacent cervical vertebral body. Radiographic findings
consistent with croup are a narrowed subglottic area on anteroposterior view (the
“steeple sign”) and possibly ballooning of the hypopharynx best appreciated on
the lateral view.

Afebrile Child
In the afebrile child with acute onset of stridor, the child’s age, the duration of
symptoms, and the likelihood of foreign-body aspiration are all key elements to
consider. Emergent otolaryngologic or surgical consultation should be obtained in
a child with an evidence of airway obstruction if either aspirated foreign body or
trauma is a likely cause of stridor. Stridor from anaphylaxis follows exposure to
an allergen, and may be associated with vomiting, wheezing, facial or oral edema,
urticaria, or hypotension. Angioneurotic edema, an autosomal-dominant trait, is

characterized by rapid onset of swelling without discoloration, urticaria, or pain.
Symptoms may occur in affected patients as young as 2 years of age but usually
are not severe until adolescence. Symptoms may be precipitated by trauma,
emotional stress, or menses. Determination of the C1 -esterase inhibitor level
should be considered if angioneurotic edema is suspected. (See Chapter 85
Allergic Emergencies .)