Obstruction of the bronchi can result from tumours (tumour), mucous plugs, foreign objects (e.g., coins, food, candy), or abscesses (abscess). The obstruction in turn may lead to accumulation and stagnation of secretions and infections and loss of tone in the bronchial walls. Short-term infections, such as measles, whooping cough, pneumonia, or influenza, cannot by themselves cause bronchiectasis, but they can cause ulcers (ulcer) or weak spots in the bronchial walls. Chronic infections cause continued inflammation of the bronchial walls. The elastic and muscle fibres tend to degenerate in these circumstances, and this degeneration allows the dilatation of the bronchi. Once dilatation occurs, secretions tend to accumulate, and infection spreads and intensifies.

Clinically, the disease is manifested by the presence of infective agents and by an overabundance of mucous secretions. Coughing may produce a thick purulent discharge from the passageways. In severe cases the sputum discharge may be heavy and may have a strong offensive odour. Erosion of blood vessels (blood vessel) in the bronchi can result in hemoptysis, the coughing up of blood. This complication may be life-threatening if it is associated with bleeding from a bronchial artery. Severe infection produces fatigue and growth retardation in children or weight loss in adults. Other complications that can arise from bronchiectasis include recurrent pneumonia, lung abscesses, and pneumothorax, the leakage of air into the pleural space. Chronic bronchiectasis may cause clubbing of the toes and fingers. The diagnosis is generally made by computerized tomographic (CT) scanning (computerized axial tomography) of the lungs.

Treatment involves determining which segments of the lungs are afflicted and then draining them two or three times daily. Even after improvement has occurred, drainage is continued for a lengthy period. Antibiotics (antibiotic) are administered to control the infective organisms. If only one lung is diseased, surgical removal of the affected segments can occasionally be performed. With control of infection, life expectancy is normal in moderate cases.