Bronchiectasis
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Direct answer
Bronchiectasis is permanent dilatation of bronchi and bronchioles caused by necrotising or suppurative airway-wall inflammation, usually triggered by the combination of obstruction and infection. Dilated airways pool secretions that drain only with posture changes, producing the classic three-layered sputum, daily productive cough, halitosis, recurrent pneumonias, clubbing and localised crackles. Cystic fibrosis is the leading background in developed countries; post-infectious damage after measles, pertussis, adenovirus or tuberculosis, primary ciliary dyskinesia and immunodeficiency account for most of the rest.
What you must remember
- Definition: abnormal, irreversible dilatation of airways with destruction of smooth muscle and elastic tissue from inflammation, extending towards the pleura on imaging.
- Causes to recite: cystic fibrosis (commonest in the West), post-infectious (measles, pertussis, adenovirus, tuberculosis, staphylococcal pneumonia), obstruction by tumour or foreign body, primary ciliary dyskinesia, hypogammaglobulinaemia, and allergic bronchopulmonary aspergillosis.
- Kartagener syndrome: the triad of situs inversus, sinusitis and bronchiectasis, from dynein arm defects of respiratory cilia; male infertility from immotile sperm completes the picture.
- Morphology: dilated airways forming sacculations (saccular worst, cylindrical mildest, varicose intermediate), wall fibrosis with lymphoid aggregates, and luminal suppuration.
- Clinical: large-volume, foul, three-layered sputum (mucus, saliva, pus), clubbing, localised coarse crackles that shift with position, and episodic haemoptysis, sometimes massive.
- Imaging: high-resolution computed tomography is diagnostic, showing signet-ring bronchi, tram-tracking and airway dilatation not tapering peripherally — "finger-in-glove" plugging when impacted.
- Complications: pneumonia, lung abscess, empyema, massive haemoptysis requiring embolisation, cor pulmonale, metastatic brain abscess and secondary amyloidosis in longstanding disease.
Common confusion
Bronchiectasis is not simple chronic bronchitis: the airway is structurally destroyed and dilated rather than merely inflamed, with clubbing and copious purulent sputum favouring bronchiectasis. Dry or "bronchitis-free" bronchiectasis, presenting mainly with recurrent haemoptysis in upper-lobe tuberculosis, contrasts with the wet classic form. Remember that in Kartagener the root defect is ciliary immotility — situs inversus is randomised organogenesis — while in cystic fibrosis the root defect is a chloride channel, with bronchiectasis the end-result of thick, sticky mucus.
Exam-focused takeaway
Vignettes describe an adult with childhood measles or tuberculosis now producing cupfuls of layered sputum with clubbing, or a child with dextrocardia, sinusitis and recurrent pneumonia (Kartagener). Questions ask for the diagnostic modality, the cause of three-layered sputum, the triad of Kartagener, or the distant complications — brain abscess and amyloidosis — that separate bronchiectasis from COPD. Answer with airway destruction plus suppuration.
Frequently asked questions
What defines bronchiectasis pathologically?
Permanent dilatation of bronchi and bronchioles with destruction of muscular and elastic wall elements following necrotising inflammation.
What is Kartagener syndrome?
The triad of situs inversus, paranasal sinusitis and bronchiectasis caused by defective dynein arms of cilia, with associated male infertility.
Why is sputum three-layered in bronchiectasis?
Settled sputum separates into a top frothy mucus layer, a middle clear saliva layer and a bottom dense purulent layer, reflecting pooled suppuration in dilated airways.
Which investigation diagnoses bronchiectasis?
High-resolution computed tomography of the chest, showing non-tapering, signet-ring airways; plain radiographs are insensitive.
Name the distant complications of bronchiectasis.
Metastatic (brain) abscess and secondary amyloidosis from chronic suppuration, besides pneumonia, massive haemoptysis and cor pulmonale.