Bronchiectasis is a chronic lung condition characterized by the permanent damage and widening of the airways (bronchi). This structural damage prevents the airways from effectively clearing mucus, leading to a buildup of thick secretions. The resulting environment traps bacteria, causing a cycle of recurrent infections, inflammation, and further airway destruction. Diagnosis combines a careful review of symptoms with specialized imaging and laboratory tests to confirm the condition and determine its underlying cause.
Initial Clinical Assessment and Suspicion
The diagnostic process begins when a patient reports specific, persistent symptoms. A chronic cough lasting at least eight weeks and involving the daily production of large amounts of thick, often discolored sputum is a primary indicator. Patients may also experience shortness of breath, fatigue, and recurrent chest infections requiring antibiotic treatment.
During the physical examination, the physician listens to the patient’s lungs. Non-specific sounds, such as crackles or wheezing, may be heard, especially toward the base of the lungs, suggesting fluid or obstructed airways. The combination of a long-standing productive cough and characteristic sounds creates a strong clinical suspicion, prompting the need for definitive imaging.
High-Resolution Computed Tomography (HRCT)
High-Resolution Computed Tomography (HRCT) of the chest is the definitive method used to confirm the structural damage defining bronchiectasis. Unlike a standard chest X-ray, which often appears normal, HRCT provides detailed cross-sectional images of the lungs. HRCT’s ability to clearly visualize small airway structures is essential for diagnosis.
The scan reveals the characteristic permanent widening and thickening of the bronchial walls. One common finding is the “signet ring” sign, which occurs when a dilated bronchus is viewed next to its accompanying, smaller pulmonary artery. In bronchiectasis, the dilated airway appears significantly larger than the artery, resembling the gem on a finger ring.
Another distinct imaging feature is the “tram track” sign, seen when widened airways run parallel to the imaging plane. This appearance is created by the thickened, non-tapering walls of the dilated bronchi, resembling parallel lines or railroad tracks. HRCT also classifies the type of bronchiectasis, which can appear as cylindrical, varicose, or cystic.
Confirming Disease Severity and Identifying the Cause
Once the anatomical diagnosis is confirmed by HRCT, follow-up tests assess functional impairment and search for the underlying cause of the lung damage. Functional testing, primarily spirometry, measures the patient’s lung mechanics and airflow. Spirometry involves the patient forcefully exhaling into a device, measuring how much air is exhaled and how quickly, revealing any airflow obstruction. PFTs help determine the physiological impact, as the severity of anatomical changes does not always correlate with the degree of breathing difficulty.
The results guide management by identifying if the patient has an obstructive, a restrictive, or a combined pattern. Laboratory tests are equally important, identifying specific factors that contributed to the condition and guiding tailored long-term management.
A sputum culture is performed to identify the specific bacteria, fungi, or other pathogens colonizing the airways. Identifying organisms like Pseudomonas aeruginosa or Haemophilus influenzae guides the choice of antibiotic therapy. Blood tests screen for systemic or genetic conditions that may have caused the bronchiectasis, such as immune deficiencies, cystic fibrosis, or allergic bronchopulmonary aspergillosis (ABPA).