Diagnostic yield of post-bronchoscopy sputum smear in pulmonary tuberculosis.

Background: The early definitive diagnosis of pulmonary tuberculosis (TB) is important for control of the disease in the community. We performed this study to evaluate the additional gain of post-bronchoscopy sputum in the diagnosis of pulmonary TB.

Methods: Bronchoscopy and bronchoalveolar lavage were performed for 126 patients suspected of pulmonary TB who either had 3 negative sputum smears for acid-fast bacilli or could not expectorate. After bronchoscopy the patients were asked to give sputum samples for 3 consecutive days. All of the obtained specimens were investigated for Mycobacterium tuberculosis by smear and culture.

Results: Pulmonary TB was confirmed in 56 patients. Among all confirmed cases, the sensitivity of bronchoalveolar lavage smear was 57.1% (32 of 56), sensitivity of post-bronchoscopy smear was 76.7% (43 of 56), and the yield of a combination of the 2 methods was 83.9% (47 of 56). Results of post-bronchoscopy sputum smears were not significantly related to sex, age, human immunodeficiency virus (HIV) infection, presence of cavitary lesions on chest X-ray, or the ability to expectorate before bronchoscopy (p > 0.05).

Conclusions: Evaluation of post-bronchoscopy sputum smears is helpful for earlier diagnosis of pulmonary TB and is an inexpensive and accessible assay.