Diagnosis of Bronchitis
Distinguish Between Acute Bronchitis and Bronchiolitis First
The diagnosis of bronchitis depends entirely on patient age: bronchiolitis affects children under 2 years, while acute bronchitis occurs in older children and adults. 1, 2
For Children Under 2 Years: Bronchiolitis
Clinical Diagnosis Without Testing
Diagnose bronchiolitis based on history and physical examination alone—do not routinely order chest radiographs, laboratory studies, or RSV testing. 1, 2
Required Clinical Features
- Viral upper respiratory prodrome (rhinorrhea, congestion) followed by lower respiratory signs 2
- Lower respiratory signs: tachypnea, wheezing, rales, and cough 2
- Increased respiratory effort: grunting, nasal flaring, intercostal/subcostal retractions 2
Critical History Elements
- Age under 2 years (most commonly under 12 months) 1
- Effects on feeding and hydration status 2
- Mental status changes (lethargy or irritability) 2
Physical Examination Specifics
- Count respiratory rate for full 60 seconds 2
- Tachypnea ≥70 breaths/minute indicates increased risk for severe disease 1, 2
- Perform serial observations over time rather than relying on a single examination, as findings vary substantially 1, 2
Risk Factors for Severe Disease
Assess these factors to guide management decisions 1, 2:
- Age <12 weeks
- Prematurity (gestational age <37 weeks)
- Hemodynamically significant congenital heart disease
- Chronic lung disease/bronchopulmonary dysplasia
- Immunodeficiency
- In utero smoke exposure
When Testing May Be Indicated
Chest radiography is useful only when: 1
- The hospitalized child does not improve at the expected rate
- Disease severity requires further evaluation
- Another diagnosis (such as pneumonia) is suspected
Routine testing increases costs without improving outcomes and may lead to inappropriate antibiotic prescribing. 2
For Older Children and Adults: Acute Bronchitis
Clinical Diagnosis
Acute bronchitis is a clinical diagnosis characterized by acute cough due to inflammation of the trachea and large airways without evidence of pneumonia. 3, 4
Exclude Pneumonia First
Do not diagnose acute bronchitis if any of these findings are present—obtain chest radiograph to rule out pneumonia: 1
- Heart rate >100 beats/min
- Respiratory rate >24 breaths/min
- Oral temperature >38°C
- Chest examination findings of focal consolidation, egophony, or fremitus
The absence of all four findings reduces the likelihood of pneumonia sufficiently to eliminate the need for chest radiography. 1
Consider Pertussis
- Cough persists >2 weeks
- Paroxysmal cough, whooping sound, or post-tussive vomiting present
- Recent pertussis exposure documented
Key Clinical Features
- Acute cough (with or without sputum production) lasting typically 2-3 weeks 3, 5, 4
- Purulent sputum does not distinguish bacterial from viral infection 1, 5
- Viruses cause >90% of cases 5
No Routine Testing Required
Diagnostic testing is not indicated unless there is concern for pneumonia, influenza, COVID-19, or pertussis. 4
Common Pitfalls to Avoid
- Do not order chest radiographs for typical bronchiolitis—this leads to unnecessary antibiotic prescribing without improving outcomes 1, 2
- Do not assume green or purulent sputum indicates bacterial infection—this finding does not reliably differentiate viral from bacterial causes 1, 5
- Do not diagnose acute bronchitis in patients with vital sign abnormalities—these patients require pneumonia evaluation 1
- Do not rely on single physical examination in bronchiolitis—serial observations provide more accurate assessment 1, 2