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    Acute Bronchitis – Diagnosis

    Cardinal Presentations / Presenting Problems, Respiratory

    Last Updated Jan 02, 2023
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    By Kevin Shi, Mark Kang

    First 5 Minutes

    • Rule out respiratory failure or pneumosepsis.
    • Rule in/out COPD/asthma.


    • Lower respiratory tract infection characterized by inflammation of the large airways, typically self-limiting with cough lasting 1-3 weeks with or without sputum production in those who do not have COPD.
    • Characterized by hyperemic and edematous mucous membrane lining of the bronchi, reducing mucociliary function.
    • Respiratory viruses are most common cause leading to the incidence being highest in late fall/winter, with bacteria being an uncommon cause of acute bronchitis.
    • Other triggers include noninfectious agents such as inhalation of dust, chemical pollutants or smoking.

    Diagnostic Process

    Signs and Symptoms

    • Cough persisting for 1 to 3 weeks with or without sputum production.
    • Headache.
    • Nasal congestion.
    • Sore throat.
    • Wheezing.
    • Mild dyspnea.
    • General malaise.
    • Muscle aches.

    Physical Exam

    • Wheezing and rhonchi may be auscultated.
    • Reduced air intake in lower lobes.


    • Acute bronchitis is a clinical diagnosis of exclusion made on history and physical exam.
    • It should be suspected in patients with persistent cough that had an acute onset lasting 1-3 weeks without clinical findings of pneumonia (such as fever, rales on auscultation, tachypnea, consolidation on chest x-ray).
    • Testing for pathogens will not change management and therefore is not recommended unless there is suspicion for COVID-19 or influenza in high-risk patients.
    • Chest x-ray may be useful to exclude other diagnoses especially when pneumonia can not be excluded. It may show thickening of bronchial walls in lower lobes but are commonly either normal or have nonspecific findings in the setting of acute bronchitis (31 up to date).
    • Other studies that may be considered in the correct clinical context to rule out other diagnoses include:
      • CBC with differential.
      • Procalcitonin levels (to identify bacterial vs nonbacterial infections).
      • Blood cultures (if bacteremia suspected).
      • Bronchoscopy (to rule out tuberculosis, tumours, other chronic diseases).
      • Spirometry (for new presentation asthma or COPD).
      • Gram stain and sputum culture (if pneumonia suspected).

    Differential Diagnoses

    • Pneumonia.
    • COVID-19.
    • Asthma.
    • Gastroesophageal reflux.
    • Postnasal drip syndrome.
    • ACE inhibitor use.
    • Heart failure.
    • Pulmonary embolism.

    Quality Of Evidence?


    Diagnosis of acute bronchitis is one of exclusion and made on history and physical with additional tests to rule out other causes.


    Related Information

    Reference List

    1. File TM. Acute Bronchitis. In: UpToDate. Waltham, MA. Accessed December 12, 2022. Available from: https://www.uptodate.com/contents/acute-bronchitis-in-adults?search=acute%20bronchitis&source=search_result&selectedTitle=2~111&usage_type=default&display_rank=2#H26

    2. Singh A, Avula A, Zahn E. Acute Bronchitis. [Updated 2022 Aug 15]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK448067/

    3. Wenzel RP, Fowler AA. Clinical practice. Acute bronchitis. N Engl J Med. 2006 Nov 16;355(20):2125-30. [PubMed]


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