Acute bronchitis
Differentials
Coronavirus disease 2019 (COVID-19)
SIGNS / SYMPTOMS
Residence in/travel to a country/area or territory with local transmission, or close contact with a confirmed or probable case of COVID-19, in the 14 days prior to symptom onset.
The situation is evolving rapidly; see our COVID-19 topic for further information.
INVESTIGATIONS
Real-time reverse transcription polymerase chain reaction (RT-PCR): positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA.
Pneumonia
SIGNS / SYMPTOMS
Patients with pneumonia often have a higher fever than patients with acute bronchitis, may appear more ill, and have rales on lung examination.
INVESTIGATIONS
CXR will detect an infiltrate from pneumonia that will not be present in acute bronchitis.
Allergic rhinitis
SIGNS / SYMPTOMS
Patients with allergic rhinitis often have postnasal drip causing a cough. On examination, acute rhinitis should be evident on nasal examination and from posterior pharyngeal drainage.
INVESTIGATIONS
None.
Asthma
SIGNS / SYMPTOMS
Patients with asthma have bilateral wheezing; the main difference between asthma and acute bronchitis is the chronicity of bronchospasm. In asthma, bronchospasm is recurrent and progressive.
INVESTIGATIONS
Pulmonary function test may be useful between bouts of acute bronchitis to diagnose asthma in patients who have residual obstructive findings.
Pertussis infection
SIGNS / SYMPTOMS
Cough has characteristic whoop in children with pertussis, although this is usually not present in adolescents and adults with the infection.
INVESTIGATIONS
Cultures, polymerase chain reaction, or direct fluorescent antibody testing for Bordetella pertussis will be positive.
Congestive heart failure (CHF)
SIGNS / SYMPTOMS
Patients with CHF may cough but also have other symptoms and signs such as dyspnoea on exertion, orthopnoea, rales on lung examination, peripheral oedema, raised jugular venous pressure, and a history of cardiac problems.
INVESTIGATIONS
CXR shows pulmonary vascular congestion and may show cardiomegaly in CHF.
Reflux oesophagitis
SIGNS / SYMPTOMS
Aspiration from reflux oesophagitis may cause a non-productive cough that is usually chronic in nature. Burning and chest pain characteristic of reflux may be helpful in differentiating this from acute bronchitis. If wheezing is present, often it is only on the right, where aspiration is most common.
INVESTIGATIONS
Upper gastrointestinal endoscopy may show oesophageal inflammation or erosions with reflux. pH monitoring also can be helpful for detecting acid in the distal oesophagus.
Upper respiratory infection/common cold
SIGNS / SYMPTOMS
Viral upper respiratory infections and acute bronchitis may be indistinguishable. Indeed, many advocate calling acute bronchitis a 'chest cold' to denote that viral bronchitis is often simply an extension from an upper respiratory illness. The productive cough from a common cold can be from inflammation of the trachea or bronchial tree or can result from postnasal drainage from an upper respiratory infection.
INVESTIGATIONS
None.
Upper airway cough syndrome
SIGNS / SYMPTOMS
Cough ≥8 weeks (usually dry).
Unpleasant sensation in the throat is a key diagnostic feature.
Postnasal drip.
Oropharyngeal examination reveals a cobblestone appearance to the posterior oropharyngeal wall and local upper airway structures.
INVESTIGATIONS
Response to trial of empirical therapy with a first-generation antihistamine plus a decongestant within 2 weeks.
Medication/environmental exposures
SIGNS / SYMPTOMS
Several medication or environmental exposures can also cause an acute cough. These include the use of ACE inhibitors or occupational exposures to dusts or chemicals. In many of these cases, such as ACE inhibitor use, the cough is non-productive. In occupational exposures, generally symptoms are restricted to the cough without any other systemic symptoms such as fever, headaches, or lethargy.
INVESTIGATIONS
None; the diagnosis should be made based on history of exposure to agents that can cause a cough.
Lung cancer
SIGNS / SYMPTOMS
Symptoms persist beyond 30 days. May see haemoptysis and/or systemic signs such as weight loss or poor appetite.
INVESTIGATIONS
CT of chest or chest radiograph may detect lesion.
Bronchoscopy may find bronchial lesion.
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