Bronchiectasis Workup

Updated: Oct 12, 2017
  • Author: Ethan E Emmons, MD; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Workup

Approach Considerations

In a typical patient, bronchiectasis is suspected on the basis of the clinical presentation, especially if purulent sputum is present and other conditions (eg, pneumonia, lung abscess) have been ruled out. A sputum analysis may be used to further strengthen clinical suspicion.

Radiographic studies, specifically CT scanning, then may be used to confirm the diagnosis. Once the diagnosis is confirmed, additional laboratory testing may be useful to determine the underlying cause. Although many causes are untreatable, identifying treatable conditions is paramount. In a significant percentage of patients, no readily identifiable cause is found.

The choice of laboratory tests may vary and should be tailored to the individual patient and clinical situation. However, high-resolution CT (HRCT) scanning is the criterion standard for the diagnosis of bronchiectasis. [2, 3, 4]

The anatomical distribution of bronchiectasis may be important in helping diagnose any associated condition or cause of bronchiectasis, as follows:

  • Bronchiectasis as a result of infection generally involves the lower lobes, the right-middle lobe, and the lingula
  • Right-middle lobe involvement alone suggests right-middle lobe syndrome, an anatomic dysfunction, or a neoplastic cause with secondary mechanical obstruction
  • Bronchiectasis caused by cystic fibrosis (CF), Mycobacterium tuberculosis infection , or chronic fungal infections tends to affect the upper lobes, although this is not universal in CF
  • Allergic bronchopulmonary aspergillosis (ABPA) also affects the upper lobes but usually involves the central bronchi, whereas most other forms of bronchiectasis involve distal bronchial segments
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Sputum Analysis

A sputum analysis may reinforce the diagnosis of bronchiectasis and add significant information regarding potential etiologies. Once sputum is allowed to settle, the examination may reveal Dittrich plugs, small white or yellow concretions. A Gram stain and culture result may reveal evidence of microorganisms, including mucoid Pseudomonas species and Escherichia coli, which suggest CF but are not diagnostic.

Chronic bronchial infection with nonmucoid Pseudomonas aeruginosa is becoming much more common in patients with non-CF bronchiectasis. The presence of eosinophils and golden plugs containing hyphae suggests Aspergillus species, although this finding alone is not diagnostic of ABPA.

Perform a smear and culture of sputum for mycobacteria and fungi. Atypical mycobacterial infection is a common cause of bronchiectasis in the older population, especially in those with underlying structural lung disease.

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CBC Count

The CBC count is often abnormal in patients with bronchiectasis. Typical findings are nonspecific and include anemia and an elevated white blood cell count with an increased percentage of neutrophils. An increased percentage of eosinophils is one criterion for ABPA. Alternatively, polycythemia secondary to chronic hypoxia may be observed in advanced cases.

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Quantitative Immunoglobulin levels

Quantitative immunoglobulin levels, including IgG subclasses, IgM, and IgA, are useful to exclude hypogammaglobulinemia. Note, however, that on rare occasions, bronchiectasis may be seen in patients with antibody production deficiency but normal to low-normal IgG levels. In situations such as these, evaluating antibody response to Haemophilus influenzae and pneumococcal vaccines may be useful.

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Quantitative Alpha1-Antitrypsin Levels

Quantitative serum alpha1-antitrypsin (AAT) levels are used to rule out AAT deficiency. In addition to a suggestive family history, clinical features of emphysema that suggest the possibility of AAT deficiency and the need for serum testing include onset at an early age (45 y or less) and the absence of a recognized risk factor (eg, smoking, occupational dust exposure).

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Pilocarpine Iontophoresis (Sweat Test)

Pilocarpine iontophoresis (sweat test) was the criterion standard test to evaluate for CF. However, genetic analysis has now become standard and may be performed to look for evidence of mutations consistent with CF and to look for potential variants, such as Young syndrome. [28]

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Aspergillus Precipitins and Serum Total IgE levels

Aspergillus precipitins and serum total IgE levels are important in making the diagnosis of ABPA. Diagnostic criteria for ABPA include a total serum IgE level greater than 1000 IU/mL or a greater than 2-fold rise from baseline.

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Autoimmune Screening Tests

Rheumatoid factor and/or other screening tests for autoimmune disease may be performed in the appropriate clinical setting. For example, an antinuclear antibody (ANA) assay may also be considered.

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Computed Tomography

CT scanning (see the image below), particularly high-resolution CT (HRCT) scanning of the chest, has replaced bronchography as the defining modality of bronchiectasis. CT sensitivity and specificity reportedly are 84-97% and 82-99%, respectively, but may be higher at referral centers. [84]

Additional advantages of HRCT scanning include noninvasiveness, avoidance of possible allergic reactions to contrast media, and information regarding other pulmonary processes. The 3 forms of bronchiectasis in the Reid classification can be visualized by HRCT. [1]

This CT scan depicts areas of both cystic bronchie This CT scan depicts areas of both cystic bronchiectasis and varicose bronchiectasis.

The following are noteworthy aspects of CT findings in bronchiectasis:

  • Cylindrical bronchiectasis has parallel tram track lines, or it may have a signet-ring appearance composed of a dilated bronchus cut in a horizontal section with an adjacent pulmonary artery representing the stone
  • The diameter of the bronchus lumen is normally 1-1.5 times that of the adjacent vessel; a diameter greater than 1.5 times that of the adjacent vessel is suggestive of bronchiectasis
  • Varicose bronchiectasis has irregular or beaded bronchi, with alternating areas of dilatation and constriction
  • Cystic bronchiectasis has large cystic spaces and a honeycomb appearance; this contrasts with the blebs of emphysema, which have thinner walls and are not accompanied by proximal airway abnormalities

For more information on the radiologic approach to bronchiectasis, see Bronchiectasis Imaging.

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Radiography

Posterior-anterior and lateral chest radiographs should be obtained in all patients. Expected general findings include increased pulmonary markings, honeycombing, atelectasis, and pleural changes. Specific findings may include linear lucencies and parallel markings radiating from the hila (tram tracking) in cylindrical bronchiectasis, dilated bronchi in varicose bronchiectasis, and clustered cysts in cystic bronchiectasis. In the appropriate clinical setting, chest radiograph findings are occasionally sufficient for confirming the diagnosis of bronchiectasis.

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Pulmonary Function Tests

Pulmonary function test results may be normal or abnormal and may reflect underlying comorbidities as well as providing information regarding predisposing conditions. These tests are useful in obtaining a functional assessment of the patient, as well as allowing for objective determination of the deterioration of a patient's pulmonary function when baseline studies are available.

The most common abnormality is an obstructive airway defect, which may even be found in patients without a prior smoking history. In addition, patients with bronchiectasis have higher rates of yearly decline in forced expiratory volume in 1 second (FEV1) than patients without bronchiectasis. [69, 85] In patients with non-CF bronchiectasis, risk factors for a more rapid decline in FEV1 include colonization with Pseudomonas aeruginosa and higher concentrations of proinflammatory markers. [86]

Obstruction in bronchiectasis is not usually reversible with bronchodilator therapy. However, a subgroup of patients may develop hyperreactive airways in conjunction with their bronchiectasis that will respond to bronchodilators.

Restriction may be observed in patients with severe advanced disease secondary to scarring and atelectasis, but this is not common. Traction bronchiectasis most often occurs in the setting of a restrictive lung defect from underlying fibrosis.

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Electron Microscopic Examination

Perform electron microscopic examination of sperm and respiratory epithelium to observe for evidence of primary ciliary structural abnormalities and dyskinesia. These will be found in disorders such as primary ciliary dyskinesia.

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Bronchography

Bronchography, although once common, is now used rarely, having been replaced by HRCT scanning. [3] Bronchography is performed by instilling contrast material via a catheter or a bronchoscope and performing plain radiographic imaging. It should be performed only at facilities and by operators skilled in its use. In current practice, it is only of potential value in confirming the location of focal bronchiectasis and in excluding disease elsewhere in the setting of possible surgical resection. This procedure carries the risk of acute bronchoconstriction.

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Bronchoscopy

Bronchoscopy is generally not helpful in diagnosing bronchiectasis, but it may be useful in identifying underlying abnormalities, such as tumors, foreign bodies, or other lesions. Bronchoscopy with bronchoalveolar lavage may be used to obtain specimens for staining and culture when a primary infectious etiology or a secondary infection is suspected.

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