Bronchiectasis Diagnosis and Management

Radiologic Definition and Appearance

The signet ring sign on CT chest indicates bronchiectasis, characterized by abnormal bronchial dilation where the internal diameter of a bronchus appears larger than its accompanying pulmonary artery, according to the American College of Radiology 1
The bronchus-to-artery ratio exceeds 1:1 when the signet ring sign is present, confirming pathologic airway dilation, as recommended by the American Thoracic Society 1

HRCT scanning has sensitivity and specificity exceeding 90% for diagnosing bronchiectasis, making it the diagnostic procedure of choice when this condition is suspected, as stated by the American College of Chest Physicians 1
The signet ring sign is more reliable than conventional chest radiographs, which may appear normal in early bronchiectasis or show only nonspecific findings, according to the European Respiratory Society 1

When the signet ring sign is identified on CT chest, confirm the diagnosis of bronchiectasis and initiate systematic evaluation for underlying causes, as recommended by the American College of Chest Physicians 2
Investigate for post-infectious etiologies, such as childhood pneumonia, pertussis, measles, and tuberculosis, as suggested by the Infectious Diseases Society of America 2
Screen for cystic fibrosis, especially if mucoid Pseudomonas is isolated, as recommended by the Cystic Fibrosis Foundation 2
Evaluate for allergic bronchopulmonary aspergillosis if Aspergillus is present, according to the American Academy of Allergy, Asthma, and Immunology 2
Consider immunodeficiency disorders, such as common variable immunodeficiency, as stated by the International Union of Immunological Societies 1
Assess for Mycobacterium avium complex infection, as recommended by the American Thoracic Society 2
Rule out traction bronchiectasis from fibrosing lung diseases, according to the European Respiratory Society 2

Do not rely on physical examination findings alone, as crackles on auscultation do not correlate reliably with CT-diagnosed bronchiectasis, as stated by the American College of Physicians 1
Do not assume all chronic cough with sputum production is bronchiectasis, as bronchiectasis accounted for only 4% of cases with >30 mL daily sputum production, according to the American College of Chest Physicians 1
Recognize that 47% of bronchiectasis cases have identifiable underlying causes, with 15% having diagnoses that significantly impact treatment decisions, as recommended by the American Thoracic Society 1, 2