Differentials

SIGNS / SYMPTOMS
INVESTIGATIONS
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.

SIGNS / SYMPTOMS
INVESTIGATIONS
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.

SIGNS / SYMPTOMS
INVESTIGATIONS
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.

SIGNS / SYMPTOMS
INVESTIGATIONS
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.

SIGNS / SYMPTOMS
INVESTIGATIONS
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.

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

Patients with CHF may cough but also have other symptoms and signs such as dyspnea on exertion, orthopnea, rales on lung examination, peripheral edema, raised jugular venous pressure, and a history of cardiac problems.

INVESTIGATIONS

CXR shows pulmonary vascular congestion and may show cardiomegaly in CHF.

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

Aspiration from reflux esophagitis may cause a nonproductive 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 esophageal inflammation or erosions with reflux. pH monitoring also can be helpful for detecting acid in the distal esophagus.

SIGNS / SYMPTOMS
INVESTIGATIONS
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.

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

Cough ≥8 weeks (usually dry).

Unpleasant sensation in the throat is a key diagnostic feature.

Postnasal drip.

Oropharyngeal exam reveals a cobblestone appearance to the posterior oropharyngeal wall and local upper airway structures.

INVESTIGATIONS

Response to trial of empiric therapy with a first-generation antihistamine plus a decongestant within 2 weeks.

SIGNS / SYMPTOMS
INVESTIGATIONS
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 nonproductive. In occupational exposures, generally symptoms are restricted to the cough, without any other systemic symptoms such as fever, headaches, or lethargy.

INVESTIGATIONS

None; diagnosis should be made based on history of exposure to agents that can cause a cough.

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

Symptoms persist beyond 30 days. May see hemoptysis 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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