croup- clinical features, evaluation, and diagnosis

7/21/2019 Croup- Clinical Features, Evaluation, And Diagnosis

http://slidepdf.com/reader/full/croup-clinical-features-evaluation-and-diagnosis 1/22

25/11/2015 Croup: Clinical features, evaluation, and diagnosis

http://www.uptodate.com/contents/croup-clinical-features-evaluation-and-diagnosis?topicKey=PEDS%2F6002&elapsedTimeMs=0&source=search_result&sea… 1/22

Official reprint from UpToDatewww.uptodate.com ©2015 UpToDate

Author Charles R Woods, MD, MS

Section EditorsSheldon L Kaplan, MDGregory Redding, MD

Deputy Editor Carrie Armsby, MD, MPH

Croup: Clinical features, evaluation, and diagnosis

All topics are updated as new evidence becomes available and our peer review process is complete.Literature review current through: Oct 2015. | This topic last updated: Feb 18, 2015.

INTRODUCTION — Croup is a respiratory illness characterized by inspiratory stridor, cough, and

hoarseness. These symptoms result from inflammation in the larynx and subglottic airway. A barking cough

is the hallmark of croup among infants and young children, whereas hoarseness predominates in older

children and adults. Although croup usually is a mild and self-limited illness, significant upper airway

obstruction, respiratory distress, and, rarely, death, can occur.

The clinical features, evaluation, and diagnosis of croup will be discussed here. The management of croup is

discussed separately. (See "Croup: Approach to management" and "Croup: Pharmacologic and supportive

interventions".)

DEFINITIONS — The term croup has been used to describe a variety of upper respiratory conditions in

children, including laryngitis, laryngotracheitis, laryngotracheobronchitis, bacterial tracheitis, or spasmodic

croup [1]. These terms are defined below. In the past, the term croup also has been applied to laryngeal

diphtheria (diphtheritic or membranous croup), which is discussed separately. (See "Epidemiology and

pathophysiology of diphtheria" and "Clinical manifestations, diagnosis and treatment of diphtheria".)

Throughout this review, the term croup will be used to refer to laryngotracheitis. Laryngotracheobronchitis,

laryngotracheobronchopneumonitis, bacterial tracheitis, and spasmodic croup are designated specifically as

such.

®

®

Laryngitis refers to inflammation limited to the larynx and manifests itself as hoarseness [ 2]. It usuallyoccurs in older children and adults and, similar to croup, is frequently caused by a viral infection. The

etiology, management, and evaluation of other causes of hoarseness are discussed in detail

separately. (See "Hoarseness in children: Etiology and management" and "Hoarseness in children:

Evaluation".)

Laryngotracheitis (croup) refers to inflammation of the larynx and trachea [2]. Although lower airway

signs are absent, the typical barking cough will be present.

Laryngotracheobronchitis (LTB) occurs when inflammation extends into the bronchi, resulting in lower

airway signs (eg, wheezing, crackles, air trapping, increased tachypnea) and sometimes more severe

illness than laryngotracheitis alone [2]. This term commonly is used interchangeably withlaryngotracheitis, and the entities are often indistinct clinically. Further extension of inflammation into

the lower airways results in laryngotracheobronchopneumonitis, which sometimes can be complicated

by bacterial superinfection. Bacterial superinfection can be manifest as pneumonia,

bronchopneumonia, or bacterial tracheitis.

Bacterial tracheitis (also called bacterial croup) describes bacterial infection of the subglottic trachea,

resulting in a thick, purulent exudate, which causes symptoms of upper airway obstruction (picture 1).

The bronchi and lungs are typically involved, as well (ie, bacterial tracheobronchitis). Bacterial tracheitis

may occur as a complication of viral respiratory infections (usually those which manifest themselves as

LTB or laryngotracheobronchopneumonitis) or as a primary bacterial infection. (See "Bacterial

tracheitis in children: Clinical features and diagnosis".)

Spasmodic croup is characterized by the sudden onset of inspiratory stridor at night, short duration





ETIOLOGY — Croup is usually caused by viruses. Bacterial infection may occur secondarily, as described

above.

Parainfluenza virus type 1 is the most common cause of acute laryngotracheitis, especially the fall and

winter epidemics [4-6]. Parainfluenza type 2 sometimes causes croup outbreaks, but usually with milder

disease than type 1. Parainfluenza type 3 causes sporadic cases of croup that often are more severe than

those due to types 1 and 2. In multicenter surveillance of children <5 years who were hospitalized with

febrile or acute respiratory illnesses, 43 percent of children with confirmed parainfluenza infection were

diagnosed with croup [7]. Croup was the most common discharge diagnosis for children with confirmed

parainfluenza 1 (42 percent) and parainfluenza 2 (48 percent) infections but was only diagnosed in 11

percent of children with confirmed parainfluenza 3 infections.

The microbiology, pathogenesis, and epidemiology of parainfluenza infections are discussed separately.

(See "Parainfluenza viruses in children".)

A number of other viruses that typically cause lower respiratory tract disease also can cause upper

respiratory tract symptoms, including croup, as described below [6].

Croup also may be caused by bacteria. Mycoplasma pneumoniae has been associated with mild cases of

croup. In addition, secondary bacterial infection may occur in children with laryngotracheitis,

laryngotracheobronchitis, or laryngotracheobronchopneumonitis. The most common secondary bacterial

(several hours), and sudden cessation [2]. This is often in the setting of a mild upper respiratory

infection, but without fever or inflammation. A striking feature of spasmodic croup is its recurrent nature,

hence the alternate descriptive term, "frequently recurrent croup". Because of some clinical overlap

with atopic diseases, it is sometimes referred to as "allergic croup".

We consider "spasmodic croup" to be distinct from "atypical croup," although the terms are sometimes

used interchangeably. Atypical croup may be defined as recurrent episodes of croup-like symptoms

occurring beyond the typical age range of six months to three years for "viral croup" or recurrent

episodes that do not appear to be simple "spasmodic croup" [3].

Respiratory syncytial virus (RSV) and adenoviruses are relatively frequent causes of croup. The

laryngotracheal component of disease is usually less significant than that of the lower airways. (See

"Respiratory syncytial virus infection: Clinical features and diagnosis", section on 'Clinical

manifestations' and "Epidemiology and clinical manifestations of adenovirus infection", section on'Clinical presentation'.)

Human coronavirus NL63 (HCoV-NL63), first identified in 2004, has been implicated in croup and other

respiratory illnesses [8-10]. The prevalence of HCoV-NL63 varies geographically. (See

"Coronaviruses", section on 'Respiratory'.)

Measles is an important cause of croup in areas where measles remains prevalent. (See "Clinical

manifestations and diagnosis of measles".)

Influenza virus is a relatively uncommon cause of croup. However, children hospitalized with influenzal

croup tend to have longer hospitalization and greater risk of readmission for relapse of laryngeal

symptoms than those with parainfluenzal croup. (See "Seasonal influenza in children: Clinical features

and diagnosis".)

Rhinoviruses, enteroviruses (especially Coxsackie types A9, B4, and B5, and echovirus types 4, 11,

and 21), and herpes simplex virus are occasional causes of sporadic cases of croup that are usually

mild. (See appropriate topic reviews).

Metapneumoviruses cause primarily lower respiratory tract disease similar to RSV, but upper

respiratory tract symptoms have been described in some patients [11]. (See "Human metapneumovirus

infections".)





pathogens include Staphylococcus aureus, Streptococcus pyogenes, and S. pneumoniae [1].

EPIDEMIOLOGY — Croup most commonly occurs in children 6 to 36 months of age. It is seen in younger

infants (as young as three months) and in preschool children, but it is rare beyond age six years [ 1,12]. It is

more common in boys, with a male:female ratio of about 1.4:1 [ 1,12-14].

Family history of croup is a risk factor for croup and recurrent croup. In a case-control study, children whose

parents had a history of croup were 3.2 times as likely to have an episode of croup and 4.1 times as likely to

have recurrent croup as children with no parental history of croup [ 15]. Parental smoking, a well-recognized

risk factor for respiratory tract infections in children, does not appear to increase the risk of croup [ 15,16].

(See "Secondhand smoke exposure: Effects in children", section on 'Respiratory symptoms and illness' .)

Most cases of croup occur in the fall or early winter, with the major incidence peaks coinciding with

parainfluenza type 1 activity (often in October) and minor peaks occurring during periods of respiratory

syncytial virus or influenza virus activity. (See "Respiratory syncytial virus infection: Clinical features and

diagnosis", section on 'Seasonality' and "Seasonal influenza in children: Clinical features and diagnosis",

section on 'Influenza activity'.)

Emergency department (ED) visits for croup are most frequent between 10:00 PM and 4:00 AM. However,

children seen for croup between noon and 6:00 PM are more likely to be admitted to the hospital [ 4,17]. A

morning peak between 7:00 AM and 11:00 AM in ED visits for croup also has been noted [ 14].

Hospital admissions for croup have declined steadily since the late 1970s. In an analysis of data from the

National Hospital Discharge Surveys from 1979 through 1997, the estimated number of annual

hospitalizations for croup decreased from 48,900 to 33,500 [5]. Estimates of annual hospitalization rates for

croup caused by parainfluenza virus types 1 to 3 from 1994 to 1997 were 0.4 to 1.1 per 1000 children for

children younger than one year and 0.24 to 0.61 per 1000 children for children between one and four years.

Approximately one-half of these hospitalizations were attributed to parainfluenza type 1.

In a six-year (1999 to 2005) population-based study, 5.6 percent of children with a diagnosis of croup in the

ED required hospital admission. Among those discharged home, 4.4 percent had a repeat ED visit within 48

hours [14].

PATHOGENESIS — The viruses that cause croup typically infect the nasal and pharyngeal mucosal

epithelia initially and then spread locally along the respiratory epithelium to the larynx and trachea.

The anatomic hallmark of croup is narrowing of the trachea in the subglottic region. This portion of the

trachea is surrounded by a firm cartilaginous ring such that any inflammation results in narrowing of the

airway. In addition to this "fixed" obstruction, dynamic obstruction of the extrathoracic trachea below the

cartilaginous ring may occur when the child struggles, cries, or becomes agitated. The dynamic obstruction

occurs as a result of the combination of high negative pressure in the distal extrathoracic trachea and the

floppiness of the tracheal wall in children.

Laryngoscopic evaluation of patients during acute laryngotracheitis shows redness and swelling of the lateral

walls of the trachea. In severe cases, the subglottic airway may be reduced to a diameter of 1 to 2 mm. In

addition to mucosal edema and swelling, fibrinous exudates and, occasionally, pseudomembranes can build

up on the tracheal surfaces and contribute to airway narrowing. The vocal cords and laryngeal tissues also

can become swollen, and cord mobility may be impaired [ 2,18-20]. Autopsy studies in children with

laryngotracheitis show infiltration of histiocytes, lymphocytes, plasma cells, and neutrophils into edematous

lamina propria, submucosa, and adventitia of the larynx and trachea [21-23].

In spasmodic croup, findings on direct laryngoscopy demonstrate noninflammatory edema [18]. This

suggests that there is no direct viral involvement of the tracheal epithelium.

Patients with bacterial tracheitis have a bacterial superinfection that causes thick pus to develop within thelumen of the subglottic trachea (picture 1). Ulcerations, pseudomembranes, and microabscesses of the

mucosal surface occur. The supraglottic tissues usually are normal. (See "Bacterial tracheitis in children:





Clinical features and diagnosis", section on 'Pathogenesis and pathology'.)

Host factors — Only a small fraction of children with parainfluenza virus infections develop overt croup.

This suggests that host (or genetic) factors play a role in the pathogenesis. Host factors that may contribute

to the development of croup include functional or anatomic susceptibility to upper airway narrowing,

variations in immune response, and predisposition to atopy [14].

Underlying host factors that predispose to clinically significant narrowing of the upper airway include:

The potential role of the immune response was demonstrated in studies that demonstrated increased

production of parainfluenza virus-specific IgE and increased lymphoproliferative response to parainfluenza

virus antigen, and diminished histamine-induced suppression of lymphocyte transformation responses to

parainfluenza virus in children with parainfluenza virus and croup compared with those with parainfluenza

virus without croup [27,28].

CLINICAL PRESENTATION — The clinical presentation of croup depends upon the specific croup

syndrome and the degree of upper airway obstruction. Although croup usually is a mild and self-limited

illness, specific features of the history and physical examination identify children who are seriously ill or at

risk for rapid progression of disease. (See 'Evaluation' below.)

Laryngotracheitis — Laryngotracheitis typically occurs in children three months to three years of age [2].

The onset of symptoms is usually gradual, beginning with nasal irritation, congestion, and coryza. Symptoms

generally progress over 12 to 48 hours to include fever, hoarseness, barking cough, and stridor. Respiratory

distress increases as upper airway obstruction becomes more severe. Rapid progression or signs of lower airway involvement suggests a more serious illness. Cough usually resolves within three days [29]; other

symptoms may persist for seven days with a gradual return to normal [2]. Deviations from this expected

course should prompt consideration of diagnoses other than laryngotracheitis. (See 'Differential diagnosis'

below.)

The degree of upper airway obstruction is evident on physical examination, as described below. In mild

cases, the child is hoarse and has nasal congestion. There is minimal, if any, pharyngitis. As airway

obstruction progresses, stridor develops, and there may be mild tachypnea with a prolonged inspiratory

phase. The presence of stridor is a key element in the assessment of severity. Stridor at rest is a sign of

significant upper airway obstruction. As upper airway obstruction progresses, the child may become restless

or anxious. (See 'Severity assessment' below.)

When airway obstruction becomes severe, suprasternal, subcostal, and intercostal retractions may be seen.

Breath sounds can be diminished. Agitation, which generally is accompanied by increased inspiratory effort,

exacerbates the subglottic narrowing by creating negative pressure in the airway. This can lead to further

respiratory distress and agitation.

Hypoxia and cyanosis can develop, as can respiratory fatigue from sustained increased respiratory effort.

High respiratory rates also tend to correlate with the presence of hypoxia. Without intervention, the hypoxia

or fatigue can sometimes lead to death.

Spasmodic croup — Spasmodic croup also occurs in children three months to three years of age [2]. In

contrast to laryngotracheitis, spasmodic croup always occurs at night; the duration of symptoms is short,

often with symptoms subsiding by the time of presentation for medical attention; and the onset and cessation

Anatomic narrowing of the airway, from etiologies such as subglottic stenosis, laryngeal webs,tracheomalacia, laryngomalacia, laryngeal clefts, or subglottic hemangiomas [3]

Hyperactive airways, perhaps aggravated by atopy or gastroesophageal reflux, as suggested in some

children with spasmodic croup or recurrent croup [24-26]

Acquired airway narrowing from respiratory tract papillomas (human papillomavirus), post-intubation

scarring, or irritation from aspirations associated with gastroesophageal reflux





of symptoms are abrupt. Fever is typically absent, but mild upper respiratory tract symptoms (eg, coryza)

may be present. Episodes can recur within the same night and for two to four successive evenings [ 30]. A

striking feature of spasmodic croup is its recurrent nature, hence the alternate descriptive term, "frequently

recurrent croup". There may be a familial predisposition to spasmodic croup, and it may be more common in

children with a family history of allergies [24].

Early in the clinical course, spasmodic croup may be difficult to distinguish from laryngotracheitis. As the

course progresses, the episodic nature of spasmodic croup and relative wellness of the child between

attacks differentiate it from classic croup, in which the symptoms are continuous.

Although the initial presentation can be dramatic, the clinical course is usually benign. Symptoms are almost

always relieved by comforting the anxious child and administering humidified air. Rarely, children may

benefit from treatment with corticosteroids and/or nebulized epinephrine [31]. Other therapies generally are

not indicated. (See "Croup: Approach to management".)

Bacterial tracheitis — Bacterial tracheitis may present as a primary or secondary infection [32]. In primary

infection, there is acute onset of symptoms of upper airway obstruction with fever and toxic appearance. In

secondary infection, there is marked worsening during the clinical course of viral laryngotracheitis, with high

fever, toxic appearance, and increasing respiratory distress secondary to tracheal obstruction from purulent

secretions. In both of these presentations, signs of lower airway disease, such as crackles and wheezes,

may be present. However, the upper airway obstruction is the more clinically significant manifestation [2,33].

(See "Bacterial tracheitis in children: Clinical features and diagnosis", section on 'Clinical features'.)

Recurrent croup — A child who has had recurrent episodes of classic viral croup may have an underlying

condition that predisposes him or her to develop clinically significant narrowing of the upper airway.

Recurrent episodes of croup-like symptoms occurring outside the typical age range for "viral croup" (ie, six

months to three years) and recurrent episodes that do not appear to be simple "spasmodic croup" should

raise suspicion for large airway lesions, gastroesophageal reflux or eosinophilic esophagitis, or atopic

conditions [3,34-38].

Children with recurrent croup may require radiographic evaluation or bronchoscopy. (See 'Host factors'

above and 'Imaging' below.)

EVALUATION

Overview — The evaluation of children with suspected croup has several objectives, including prompt

identification of patients with significant upper airway obstruction or at risk for rapid progression of upper

airway obstruction. In addition, there are some conditions with presentations similar to that of croup that

require specific evaluations and/or interventions; these too must be promptly identified. (See 'Differential

diagnosis' below.)

During the evaluation, efforts should be made to make the child as comfortable as possible. The increased

inspiratory effort that accompanies anxiety and fear in young children can exacerbate subglottic narrowing,further diminishing air exchange and oxygenation. (See 'Pathogenesis' above.)

Rapid assessment and initial management — Rapid assessment of general appearance (including the

presence of stridor at rest), vital signs, pulse oximetry, airway stability, and mental status is necessary to

identify children with severe respiratory distress and/or impending respiratory failure. (See "Croup: Approach

to management", section on 'Respiratory care'.)

Endotracheal intubation is required in less than 1 percent of children with croup who are seen in the

emergency department. However, the need for endotracheal intubation should be anticipated in children with

progressive respiratory failure so that it can be performed in as controlled a setting as possible. Respiratory

failure is heralded by the following signs [1,39,40]:

Fatigue and listlessness

Marked retractions (although retractions may decrease with increased obstruction and decreased air





A tracheal tube that is 0.5 to 1 mm smaller than would typically be used may be required. (See "Emergency

endotracheal intubation in children", section on 'Endotracheal tube'.)

In addition to establishment of an airway, children who have severe respiratory distress require immediate

pharmacologic treatment, including administration of nebulized epinephrine and systemic or nebulized

corticosteroids. (See "Croup: Approach to management", section on 'Moderate to severe croup'.)

Once control of the airway is established and pharmacologic treatment, if necessary, is under way, the

remainder of the evaluation can proceed.

History — The history should include a description of the onset, duration, and progression of symptoms.

Factors that are associated with increased severity of illness include:

Aspects of the history that are helpful in distinguishing croup from other causes of acute upper airway

obstruction include [1,41]:

The differential diagnosis of croup is discussed in greater detail below. (See 'Differential diagnosis' below.)

Examination — The objectives of the examination of the child with croup include assessment of severity of

upper airway obstruction and exclusion of other infectious and non-infectious causes of acute upper airway

obstruction, both of which are necessary in making management decisions.

The initial examination often can be accomplished by observing the child in a comfortable position with the

caretaker. Every effort should be made to measure the child's weight and vital signs.

Aspects of the examination that are helpful in assessing the degree of upper airway obstruction and severity

of illness include:

entry)

Decreased or absent breath sounds

Depressed level of consciousness

Tachycardia out of proportion to fever

Cyanosis or pallor

Sudden onset of symptoms

Rapidly progressing symptoms (ie, symptoms of upper airway obstruction after fewer than 12 hours of

illness)

Previous episodes of croup

Underlying abnormality of the upper airway

Medical conditions that predispose to respiratory failure (eg, neuromuscular disorders)

Fever – The absence of fever from onset of symptoms to the time of presentation is suggestive of

spasmodic croup or a noninfectious etiology (eg, foreign body aspiration or ingestion, acute

angioneurotic edema).

Hoarseness and barking cough – Hoarseness and barking cough, characteristic findings in croup, are

typically absent in children with acute epiglottitis, foreign body aspiration, and angioneurotic edema.

Difficulty swallowing – Difficulty swallowing may occur in acute epiglottitis and foreign body aspiration.

A large ingested foreign body may lodge in the upper esophagus, where it distorts and narrows the

upper trachea, thus mimicking the croup syndrome (including barking cough and inspiratory stridor).

Drooling – Drooling may occur in children with peritonsillar or retropharyngeal abscesses,

retropharyngeal cellulitis, and epiglottitis. In an observational study, drooling was present in

approximately 80 percent of children with epiglottitis, but only 10 percent of those with croup [ 41].

Throat pain – Complaints of dysphagia and sore throat are more common in children with epiglottitis

than croup (approximately 60 to 70 percent versus <10 percent) [41].





These aspects of the examination are often used in clinical scoring systems to evaluate the severity of

illness and/or in making decisions regarding the need for hospital admission. (See 'Severity assessment'

below and "Croup: Approach to management", section on 'Observation and disposition'.)

Components of the examination that are useful in distinguishing croup from other causes of acute upper

airway obstruction include [39,41]:

Overall appearance – Is the child comfortable and interactive, anxious and quiet, or obtunded? Is there

stridor at rest? Stridor at rest is a sign of significant upper airway obstruction. Children with significant

upper airway obstruction may prefer to sit up and lean forward in a "sniffing" position (neck is mildly

flexed, and head is mildly extended). This position tends to improve the patency of the upper airway.

Quality of the voice – Does the child have a hoarse or diminished cry? Is the voice muffled? A muffled

"hot potato" voice is suggestive of epiglottitis, retropharyngeal abscess, or peritonsillar abscess.

Degree of respiratory distress – Signs of respiratory distress include tachypnea, hypoxemia, and

increased work of breathing (intercostal, subcostal, or suprasternal retractions; nasal flaring; grunting;

use of accessory muscles)

Tidal volume – Does there appear to be good chest expansion with inspiration, indicating adequate air

entry?

Lung examination – Are there abnormal respiratory sounds during inspiration or expiration? Inspiratory

stridor indicates upper airway obstruction, whereas expiratory wheezing is a sign of lower airway

obstruction. If there is stridor, is it present at rest or only with agitation? As discussed above, stridor at

rest is a sign of significant upper airway obstruction. Stridor will be more obvious on auscultation, since

the inspiratory noise is transmitted through the chest. The presence of crackles (rales) also suggests

lower respiratory tract involvement (eg, laryngotracheobronchitis, laryngotracheobronchopneumonitis,or bacterial tracheitis).

Assessment of hydration status – Decreased oral intake and increased insensible losses from fever

and tachypnea may result in dehydration. (See "Clinical assessment and diagnosis of hypovolemia

(dehydration) in children".)

Preferred posture – Children with epiglottitis usually prefer to sit up in the "tripod" or "sniffing position"

(picture 2A-B).

Examination of the oropharynx for the following signs:

Cherry red, swollen epiglottis, suggestive of epiglottitis•

Pharyngitis, typically minimal in laryngotracheitis, may be more pronounced in epiglottitis or

laryngitis

•

Excessive salivation, suggestive of acute epiglottitis, peritonsillar abscess, or retropharyngealabscess

•

Diphtheritic membrane•

Tonsillar asymmetry or deviation of the uvula suggestive of peritonsillar abscess•

Midline or unilateral swelling of the posterior pharyngeal wall suggestive of retropharyngeal

abscess

•

Concerns have been raised about safety of examining the pharynx in children with upper airway

obstruction and possible epiglottitis since such efforts have been reported to precipitate

cardiorespiratory arrest. However, in two series, each including more than 200 patients withepiglottitis or viral croup, direct examination of the oropharynx was not associated with sudden

clinical deterioration [32,42].





The differential diagnosis of croup is discussed in greater detail below. (See 'Differential diagnosis' below.)

Severity assessment — The severity of croup is often determined by the clinical scoring systems.

Although there are a number of validated croup scoring systems, the Westley croup score [43] has been the

most extensively studied; it is described below. No matter which system is used to assess severity, the

presence of chest wall retractions and stridor at rest are the two critical clinical features.

The elements of the Westley croup score describe key features of the physical examination [ 43]. Each

element is assigned a score, as illustrated below:

Mild croup is defined by a Westley croup score of ≤2. Typically, these children have a barking cough and

hoarse cry, but no stridor at rest. Children with mild croup may have stridor when upset or crying (ie,

agitated) and either no, or only mild, chest wall/subcostal retractions [1,39].

Moderate croup is defined by a Westley croup score of 3 to 7. Children with moderate croup have stridor at

rest, at least mild retractions, and may have other symptoms or signs of respiratory distress, but little or no

agitation [1,39].

Severe croup is defined by a Westley croup score of ≥8. Children with severe croup have significant stridor at rest, although stridor may decrease with worsening upper airway obstruction and decreased air entry

[1,39]. Retractions are severe (including indrawing of the sternum) and the child may appear anxious,

agitated, or fatigued. Prompt recognition and treatment of children with severe croup are paramount.

Imaging

Indications — Radiographic confirmation of acute laryngotracheitis is not required in the vast majority of

children with croup. Radiographic evaluation of the chest and/or upper trachea is indicated if the diagnosis is

in question, the course is atypical, an inhaled or swallowed foreign body is suspected (although the majority

are not radio-opaque), croup is recurrent, and/or there is a failure to respond as expected to therapeutic

interventions. (See 'Differential diagnosis' below and "Croup: Approach to management".)

Findings — In children with croup, a posterior-anterior chest radiograph demonstrates subglottic

narrowing, commonly called the "steeple sign" (image 1). The lateral view may demonstrate overdistention of

the hypopharynx during inspiration [44] and subglottic haziness (image 2). The epiglottis should have a

normal appearance.

In contrast, the lateral radiograph in virtually all children with epiglottitis demonstrates swelling of the

epiglottis, sometimes called the "thumb sign" (image 3). (See "Epiglottitis (supraglottitis): Clinical features

and diagnosis", section on 'Radiographic features'.)

The lateral radiograph in children with bacterial tracheitis may demonstrate only nonspecific edema or

intraluminal membranes and irregularities of the tracheal wall (image 4) [45].

Laboratory studies — Laboratory studies, which are rarely indicated in children with croup, are of limited

Examination of the cervical lymph nodes, which can be enlarged in patients with retropharyngeal or

peritonsillar abscesses.

Other physical findings may be present, depending on the particular inciting virus. As an example, rash,

conjunctivitis, exudative pharyngitis, and adenopathy are suggestive of adenovirus infection.

Otitis media (acute or with effusion) may be present as a primary viral or secondary bacterial process.

Level of consciousness: Normal, including sleep = 0; disoriented = 5

Cyanosis: None = 0; with agitation = 4; at rest = 5

Stridor: None = 0; with agitation = 1; at rest = 2

Air entry: Normal = 0; decreased = 1; markedly decreased = 2

Retractions: None = 0; mild = 1; moderate = 2; severe = 3





diagnostic utility but may help guide management in more severe cases.

Blood tests — The white blood cell (WBC) count can be low, normal, or elevated; WBC counts >10,000

cells/microL are common. Neutrophil or lymphocyte predominance may be present on the differential

[46,47]. The presence of a large number of band-form neutrophils is suggestive of primary or secondary

bacterial infection. Croup is not associated with any specific alterations in serum chemistries.

Microbiology — Confirmation of etiologic diagnosis is not necessary for most children with croup, since

croup is a self-limited illness that usually requires only symptomatic therapy. When an etiologic diagnosis is

necessary, viral culture and/or rapid diagnostic tests that detect viral antigens are performed on secretions

from the nasopharynx or throat. (See 'Etiologic diagnosis' below.)

DIAGNOSIS

Clinical diagnosis — The diagnosis of croup is clinical, based on the presence of a barking cough and

stridor, especially during a typical community epidemic of one of the causative viruses. (See 'Etiology'

above.)

Neither radiographs nor laboratory tests are necessary to make the diagnosis. However, radiographs may

be helpful in excluding other causes if the diagnosis is in question. (See 'Differential diagnosis' below.)

Etiologic diagnosis — Although not typically required in most cases of croup, identification of a specific

viral etiology may be necessary to make decisions regarding isolation for patients requiring hospitalization or

for public health/epidemiologic monitoring purposes. Testing for influenza is indicated if the results will

influence decisions regarding treatment, prophylaxis of contacts, or performance of other diagnostic tests;

laboratory confirmation should not delay the initiation of antiviral therapy for influenza when clinical and

seasonal considerations are compatible with influenza as the potential etiology of croup. (See "Seasonal

influenza in children: Clinical features and diagnosis", section on 'Laboratory diagnosis' and "Seasonal

influenza in children: Prevention and treatment with antiviral drugs", section on 'Timing of treatment'.)

Diagnosis of a specific viral etiology can be made by viral culture of secretions from the nasopharynx or

throat. Rapid tests that detect viral antigens in these secretions are commercially available for many

respiratory viruses. The diagnosis of specific viral infections is discussed in detail in individual topic reviews:

In addition, multiplex tests, which assess the presence of multiple agents at the same time, and PCR-based

tests are becoming more widely available [48].

DIFFERENTIAL DIAGNOSIS — The differential diagnosis of croup includes other causes of stridor and/or

respiratory distress. The primary considerations are those with acute onset, particularly those that may

rapidly progress to complete upper airway obstruction, and those that require specific therapy. Underlying

anatomic anomalies of the upper airway also must be considered, since they may contribute to more severe

Parainfluenza (see "Parainfluenza viruses in children", section on 'Diagnosis')

Influenza (see "Seasonal influenza in children: Clinical features and diagnosis", section on 'Diagnosis' )

Respiratory syncytial virus (see "Respiratory syncytial virus infection: Clinical features and diagnosis",

section on 'Laboratory diagnosis')

Adenovirus (see "Diagnosis, treatment, and prevention of adenovirus infection", section on 'Diagnostic

tests of choice for different adenovirus syndromes')

Measles (see "Clinical manifestations and diagnosis of measles", section on 'Diagnosis')

Enteroviruses (see "Clinical manifestations and diagnosis of enterovirus and parechovirus infections",

section on 'Laboratory diagnosis')

Metapneumovirus (see "Human metapneumovirus infections", section on 'Diagnosis')

Coronavirus (see "Coronaviruses", section on 'Diagnosis')




http://www.uptodate.com/contents/croup-clinical-features-evaluation-and-diagnosis?topicKey=PEDS%2F6002&elapsedTimeMs=0&source=search_result&se… 11/22

cause vocal cord paralysis) [49,50]. (See "Congenital anomalies of the intrathoracic airways and

tracheoesophageal fistula", section on 'Bronchogenic cyst' and "Epidemiology, clinical features, and

diagnosis of Guillain-Barré syndrome in children", section on 'Clinical features' and "Hoarseness in children:

Etiology and management", section on 'Vocal fold paralysis'.)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics"

and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5 to 6

grade reading level, and they answer the four or five key questions a patient might have about a given

condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more

detailed. These articles are written at the 10 to 12 grade reading level and are best for patients who want

in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail

these topics to your patients. (You can also locate patient education articles on a variety of subjects by

searching on "patient info" and the keyword(s) of interest.)

SUMMARY AND RECOMMENDATIONS

th th

th th

Basics topic (see "Patient information: Croup (The Basics)")

Beyond the Basics topic (see "Patient information: Croup in infants and children (Beyond the Basics)")

The term croup has been used to describe a variety of upper respiratory conditions in children,

including laryngitis, laryngotracheitis, laryngotracheobronchitis, bacterial tracheitis, or spasmodic croup.

(See 'Definitions' above.)

Croup is usually caused by viruses. Bacterial infection may occur secondarily. Parainfluenza virus type

1 is the most common cause of croup; other causes include respiratory syncytial virus and influenza

virus. (See 'Etiology' above.)

Croup most commonly occurs in children 6 to 36 months of age. Most cases occur in the fall or early

winter. (See 'Epidemiology' above.)

Host factors that may contribute to the development of croup include functional or anatomic

susceptibility to upper airway narrowing. (See 'Pathogenesis' above.)

The clinical presentation of croup depends upon the specific croup syndrome and the degree of upper

airway obstruction. (See 'Clinical presentation' above.)

The onset of symptoms in laryngotracheitis is gradual, beginning with nasal irritation, congestion, and

coryza. Fever, hoarseness, barking cough, and stridor usually develop during the next 12 to 48 hours.

Rapid progression or signs of lower airway involvement suggest a more serious illness. (See

'Laryngotracheitis' above.)

The onset of symptoms in spasmodic croup is sudden and always occurs at night. Fever is typically

absent, but mild upper respiratory tract symptoms may be present. (See 'Spasmodic croup' above.)

Bacterial tracheitis (picture 1 and image 4) may present acutely or as marked worsening during the

course of an antecedent viral upper respiratory infection. Clinical manifestations of bacterial tracheitis

include fever, toxic appearance, and severe respiratory distress. (See 'Bacterial tracheitis' above and

"Bacterial tracheitis in children: Clinical features and diagnosis".)

The objectives of the evaluation of the child with croup include assessment of severity and exclusion of

other causes of upper airway obstruction. (See 'Overview' above.)

Rapid assessment of general appearance, vital signs, pulse oximetry, airway stability, and mental

status are necessary to identify children with severe respiratory distress and/or impending respiratory

failure. (See 'Rapid assessment and initial management' above.)





Use of UpToDate is subject to the Subscription and License Agreement.

REFERENCES

1. Cherry JD. Clinical practice. Croup. N Engl J Med 2008; 358:384.

2. Cherry JD. Croup (laryngitis, laryngotracheitis, spasmodic croup, laryngotracheobronchitis, bacterialtracheitis, and laryngotracheobronchopneumonitis) and epiglottitis (supraglottitis). In: Feigin andCherry’s Textbook of Pediatric Infectious Diseases, 7th ed, Cherry JD, Harrison GJ, Kaplan SL, et al(Eds), Elsevier Saunders, Philadelphia 2014. p.241.

3. Cooper T, Kuruvilla G, Persad R, El-Hakim H. Atypical croup: association with airway lesions, atopy,and esophagitis. Otolaryngol Head Neck Surg 2012; 147:209.

4. Peltola V, Heikkinen T, Ruuskanen O. Clinical courses of croup caused by influenza and parainfluenzaviruses. Pediatr Infect Dis J 2002; 21:76.

5. Counihan ME, Shay DK, Holman RC, et al. Human parainfluenza virus-associated hospitalizationsamong children less than five years of age in the United States. Pediatr Infect Dis J 2001; 20:646.

6. Rihkanen H, Rönkkö E, Nieminen T, et al. Respiratory viruses in laryngeal croup of young children. JPediatr 2008; 152:661.

7. Weinberg GA, Hall CB, Iwane MK, et al. Parainfluenza virus infection of young children: estimates of the population-based burden of hospitalization. J Pediatr 2009; 154:694.

8. Kuypers J, Martin ET, Heugel J, et al. Clinical disease in children associated with newly described

coronavirus subtypes. Pediatrics 2007; 119:e70.

9. Sung JY, Lee HJ, Eun BW, et al. Role of human coronavirus NL63 in hospitalized children with croup.Pediatr Infect Dis J 2010; 29:822.

10. van der Hoek L, Sure K, Ihorst G, et al. Croup is associated with the novel coronavirus NL63. PLoSMed 2005; 2:e240.

11. Døllner H, Risnes K, Radtke A, Nordbø SA. Outbreak of human metapneumovirus infection innorwegian children. Pediatr Infect Dis J 2004; 23:436.

12. Bjornson CL, Johnson DW. Croup. Lancet 2008; 371:329.

13. Segal AO, Crighton EJ, Moineddin R, et al. Croup hospitalizations in Ontario: a 14-year time-seriesanalysis. Pediatrics 2005; 116:51.

14. Rosychuk RJ, Klassen TP, Metes D, et al. Croup presentations to emergency departments in Alberta,Canada: a large population-based study. Pediatr Pulmonol 2010; 45:83.

15. Pruikkonen H, Dunder T, Renko M, et al. Risk factors for croup in children with recurrent respiratory

The history should include a description of the onset, duration and progression of symptoms, and

ascertain whether there are any underlying conditions that predispose to a more severe course. (See

'History' above.)

Aspects of the examination that are useful in assessing the severity of upper airway obstruction include

overall appearance (including the presence of stridor at rest or only with agitation), quality of voice,

work of breathing, tidal volume and air entry, and the presence of wheezing. (See 'Examination'

above.)

The diagnosis of croup is clinical, based upon the presence of a barking cough and stridor. Neither

radiographs nor laboratory tests are necessary to make the diagnosis. However, radiographs may be

helpful in excluding other causes if the diagnosis is in question. (See 'Diagnosis' above.)

The differential diagnosis of croup includes other causes of stridor and/or respiratory distress. The

primary considerations are those with acute onset, particularly those that may rapidly progress to

complete upper airway obstruction, and those that require specific therapy. Important considerations

include acute epiglottitis, peritonsillar and retropharyngeal abscesses, foreign body aspiration, acute

angioneurotic edema, upper airway injury, and congenital anomalies of the upper airway. (See

'Differential diagnosis' above.)





43. Westley CR, Cotton EK, Brooks JG. Nebulized racemic epinephrine by IPPB for the treatment of croup: a double-blind study. Am J Dis Child 1978; 132:484.

44. Mills JL, Spackman TJ, Borns P, et al. The usefulness of lateral neck roentgenograms inlaryngotracheobronchitis. Am J Dis Child 1979; 133:1140.

45. Bernstein T, Brilli R, Jacobs B. Is bacterial tracheitis changing? A 14-month experience in a pediatricintensive care unit. Clin Infect Dis 1998; 27:458.

46. Cherry JD. Newer respiratory viruses: their role in respiratory illnesses of children. In: Advances inPediatrics, Vol 20, Schulman I (Ed), Mosby Year Book, Chicago 1973. p.225.

47. Denny FW, Clyde WA Jr. Acute lower respiratory tract infections in nonhospitalized children. J Pediatr 1986; 108:635.

48. Henrickson KJ, Hoover S, Kehl KS, Hua W. National disease burden of respiratory viruses detected inchildren by polymerase chain reaction. Pediatr Infect Dis J 2004; 23:S11.

49. Lin CY, Chi H, Shih SL, et al. A 4-year-old boy presenting with recurrent croup. Eur J Pediatr 2010;169:249.

50. Hsia SH, Lin JJ, Wu CT, et al. Guillain-Barré syndrome presenting as mimicking croup. Am J EmergMed 2010; 28:749.e1.

Topic 6002 Version 20.0





GRAPHICS

Bacterial tracheitis: Endoscopy

Note the adherent mucopurulent membranes within the trachea.

Courtesy of Glenn C Isaacson, MD, FAAP, FACS.

Graphic 55364 Version 3.0





Epiglottitis: Tripod posture

This child's "tripod" positioning (trunk leaning forward, neck

hyperextended, chin thrust forward) is indicative of epiglottitis. Note the

child's toxic appearance.

Reproduced with permission from: M Douglas Baker, MD.






Child with classic presentation of acute epiglottitis

This four-year-old girl has epiglottitis caused by Haemophilus influenzae

type b.

(A) She prefers to sit and appears anxious.

(B) The child assumes the characteristic sniffing position to maximize the

patency of her airway.

Reproduced with permission from: Fleisher GR, Ludwig W, Baskin MN. Atlas of

Pediatric Emergency Medicine. Philadelphia: Lippincott Williams & Wilkins,

2004. Copyright © 2004 Lippincott Williams & Wilkins.






Lateral neck radiograph of a child with croup

Lateral neck radiograph showing subglottic narrowing (arrow) and

distended hypopharynx (arrowheads) consistent with acute

laryngotracheitis.

Courtesy of Joe Black, Diagnostic Imaging, Texas Children's Hospital.






Epiglottitis: Lateral radiograph

Lateral neck radiograph demonstrating swollen epiglottis (arrow) and

aryepiglottic folds in a child with epiglottitis due to Haemophilus

influenzae type b. The swollen epiglottis is often called a "thumb sign."

Courtesy of Evelyn Y Anthony, MD, Wake Forest University School of

Medicine.






Bacterial tracheitis: Lateral neck radiograph

Lateral neck radiograph showing intraluminal membranes and tracheal

wall irregularity consistent with bacterial tracheitis.

Courtesy of R. Paul Guillerman, MD, Department of Radiology, Baylor College

of Medicine.





Disclosures: Charles R Woods, MD, MS Other Financial Interest: Cerexa [Epiglottitis (Data Safety Monitoring Board for pediatrictrials of the antibiotic agent ceftaroline)]. Sheldon L Kaplan, MD Grant/Research/Clinical Trial Support: Pfizer [vaccine (PCV13)];

Forest Lab [antibiotic (Ceftaroline)]; Optimer [antibiotic (fidaxomicin)]. Consultant/Advisory Boards: Pfizer [vaccine (PCV13)].

Gregory Redding, MD Nothing to disclose. Carrie Armsby, MD, MPH Nothing to disclose.

Contributor disclosures are reviewed for conflicts of interest by the editorial group. When found, these are addressed by vetting

through a multi-level review process, and through requirements for references to be provided to support the content. Appropriately

referenced content is required of all authors and must conform to UpToDate standards of evidence.

Conflict of interest policy

Disclosures

croup- clinical features, evaluation, and diagnosis

Documents