Westley croup score (also searched with possessive/alternate eponym spelling where applicable, ICD-10: J05.0) is a standardized clinical scoring instrument utilized to objectively quantify the severity of acute laryngotracheobronchitis (croup) in pediatric patients1. By evaluating five distinct physiological parameters—level of consciousness, cyanosis, stridor, air entry, and chest retractions—the scoring system categorizes disease severity to guide timely therapeutic interventions, outpatient discharge planning, or pediatric intensive care unit admission1.

Etiology & Risk Factors

  • Viral Pathogens: Parainfluenza virus type 1 is the predominant causative agent, accounting for approximately 75% of viral croup cases; parainfluenza types 2 and 3, influenza A and B, respiratory syncytial virus (RSV), adenovirus, and human metapneumovirus represent secondary infectious triggers1.
  • Anatomical Predisposition: Infants and toddlers aged 6 months to 3 years possess inherently narrow, compliant upper airways, rendering them uniquely susceptible to significant airway compromise from minimal subglottic mucosal oedema1.
  • Anatomical Locus: Inflammation predominantly localizes to the subglottic region, bounded by the rigid cricoid cartilage, which prevents outward expansion and accelerates turbulent airflow.
  • Epidemiological Demographics: Peak incidence occurs during the second year of life, with a higher prevalence in autumn and early winter months, demonstrating a clear male predilection (approximately 3:2 ratio).
  • Family History & Atopy: Recurrent spasmodic croup is frequently associated with a positive family history of atopic disease, allergic rhinitis, or bronchial hyper-reactivity, though classic viral croup involves acute infectious inflammation.

Pathophysiology

The pathophysiological cascade of croup initiates with viral droplet inoculation of the nasopharyngeal mucosa, followed by caudal viral spread along the respiratory epithelium toward the larynx and trachea1. Direct viral cytopathic effect and the subsequent host cell-mediated immune response induce intense mucosal hyperaemia, capillary dilation, leukocyte infiltration, and subglottic lymphatic oedema1. Because the subglottic space is encircled by the rigid, non-expansile cricoid cartilage—the narrowest segment of the pediatric upper airway—even a 1-millimetre circumferential mucosal swelling reduces cross-sectional tracheal area by nearly 50%, exponentially increasing resistance to airflow according to Poiseuille's law. This critical mechanical narrowing generates turbulent inspiratory airflow, producing the characteristic high-pitched inspiratory stridor, while compensatory increased respiratory effort results in suprasternal, intercostal, and subcostal retractions. As work of breathing escalates, muscular fatigue can ensue, leading to alveolar hypoventilation, hypercapnia, hypoxia, and potential respiratory arrest if anti-inflammatory therapy is withheld.

Westley croup score — Pathophysiological Cascade & Clinical Flowchart 1 Viral Upper Respiratory Infection Parainfluenza virus or other respiratory pathogens infect the upper airway mucosa. 2 Subglottic Oedema & Inflammation Local immune response triggers mucosal hyperaemia, cellular infiltration, and subglottic swelling. 3 Rigid Cricoid Constriction The fixed ring of the cricoid cartilage prevents outward expansion, severely restricting luminal airflow. 4 Clinical Manifestation Emergence of barking cough, inspiratory stridor, and chest wall retractions quantified by the Westley score. 5 Therapeutic Intervention Administration of corticosteroids reduces mucosal oedema, restoring airway patency and preventing respiratory failure.

Clinical Presentation & Classic Clinical Signs

  • History & Cardinal Symptoms: Prodromal symptoms typically include low-grade fever, rhinorrhoea, and mild pharyngitis lasting 1 to 3 days, which abruptly progress over hours to a characteristic "seal-bark" or brassy cough, inspiratory stridor, hoarseness, and varying degrees of respiratory distress that classically worsen at night.
  • Physical Examination & Named Clinical Signs: Inspection reveals inspiratory stridor (initially present only with agitation, later occurring at rest), suprasternal, intercostal, and subcostal retractions, and normal or diminished breath sounds. Assessment of mental status is critical; agitation or anxiety reflects hypoxia, whereas lethargy or altered consciousness signifies severe hypercapnia and impending respiratory arrest. Absence of drooling, absence of toxic appearance, and the presence of a barking cough differentiate croup from acute epiglottitis.

Diagnostic Workup & Interpretation (Laboratory, Imaging & ECG/Pathology)

Diagnostic Modality / Test Expected Clinical & Radiological / Laboratory Finding
Gold-Standard InvestigationClinical assessment using the Westley croup score combined with exclusion of alternative upper airway emergencies (e.g., foreign body aspiration, bacterial tracheitis, epiglottitis).
Laboratory PanelComplete blood count (CBC) and inflammatory markers are generally unnecessary for routine viral croup; white blood cell counts may show normal or lymphocytic predominance, while marked leukocytosis with a left shift suggests secondary bacterial tracheitis.
Imaging / Radiology (X-ray, US, CT, MRI)Soft tissue neck radiograph (anteroposterior view) classically demonstrates the "steeple sign" (subglottic tracheal narrowing tapering toward the larynx); lateral view may show subglottic haziness and normal epiglottis, though imaging is reserved for atypical presentations.
ECG / Histopathology / ProceduralPulse oximetry is essential in moderate-to-severe disease; arterial blood gas analysis is rarely indicated unless acute respiratory failure is suspected and non-invasive monitoring is inconclusive.

Staging, Classification & Clinical Scoring Systems

Criterion / Stage / Score Component Clinical Threshold, Points & Management Implication
Level of ConsciousnessNormal, including sleep = 0 points; Disoriented, lethargic, or altered = 5 points.
CyanosisNone = 0 points; With agitation = 4 points; At rest = 5 points.
StridorNone = 0 points; With agitation = 1 point; At rest = 2 points.
Air EntryNormal = 0 points; Decreased = 1 point; Markedly decreased = 2 points.
RetractionsNone = 0 points; Mild = 1 point; Moderate = 2 points; Severe = 3 points. Total score range: 0 to 17.
Severity ClassificationMild (Score 0–2): Outpatient supportive care, oral dexamethasone. Moderate (Score 3–7): Observation, oral/IM corticosteroids, nebulized epinephrine if needed. Severe (Score 8–11): Hospital admission, nebulized epinephrine, continuous monitoring. Impending Respiratory Failure (Score ≥ 12): Urgent PICU evaluation, preparations for intubation.

Differential Diagnosis

Differential Condition Distinguishing Clinical, Biochemical & Imaging Features
Acute EpiglottitisCaused by Haemophilus influenzae type b (in unimmunized children); presents with rapid onset, high fever, drooling, dysphagia, muffled voice, and "thumbprint sign" on lateral neck radiograph; patient sits in tripod position.
Bacterial TracheitisSevere, life-threatening bacterial superinfection (Staphylococcus aureus); high fever, toxic appearance, thick purulent tracheal secretions, and lack of response to standard croup therapy; requires airway management and broad-spectrum antibiotics.
Foreign Body AspirationSudden onset of respiratory distress or choking episode without preceding viral prodrome; asymmetric breath sounds on auscultation; inspiratory chest radiograph may reveal radiopaque foreign body or air trapping.
Retropharyngeal / Peritonsillar AbscessTrismus, refusal to feed, neck swelling, posterior pharyngeal wall bulging, asymmetric tonsillar displacement, and fever; computed tomography (CT) of the neck confirms fluid collection.

Management & Treatment Protocol

  • Initial Stabilization & Resuscitation: Maintain a calm environment to minimize agitation and crying, which exacerbate upper airway obstruction; administer supplemental humidified oxygen if oxygen saturation drops below 92%, and ensure immediate availability of pediatric airway equipment.
  • First-Line Medical / Pharmacological Therapy (with exact adult dosing):
    • Corticosteroids: Single-dose oral dexamethasone at 0.6 mg/kg (maximum 16 mg) is the gold standard for all severity grades, reducing mucosal oedema and need for hospitalization. Alternative: prednisolone 1 mg/kg.
    • Nebulized Epinephrine: Indicated for moderate-to-severe croup (Westley score ≥ 3) or stridor at rest. Administer 0.5 mL of 2.25% racemic epinephrine (or weight-based L-epinephrine equivalent, e.g., 3 to 5 mL of 1:1,000 solution) via nebulizer. Patients must be monitored for at least 3 to 4 hours post-administration to observe for potential rebound stridor.
  • Surgical / Interventional Indications: Endotracheal intubation is indicated for progressive exhaustion, severe hypercapnia, recurrent cyanosis, or impending respiratory arrest refractory to medical therapy; an endotracheal tube one to two sizes smaller than age-predicted is typically required due to subglottic narrowing.

Complications & Prognosis

  • Key acute complications include upper airway obstruction, severe hypoxia, hypercapnic respiratory failure, exhaustion, and secondary bacterial infections (such as bacterial tracheitis or pneumonia).
  • Recurrent croup may occur in children with underlying airway anomalies, subglottic stenosis, or strong atopic tendencies.
  • Prognosis is exceptionally favorable for standard viral croup, with symptoms typically resolving spontaneously within 48 to 72 hours and complete recovery following corticosteroid administration. Mortality is exceedingly rare in developed healthcare settings.