Comparison of Induced Sputum and Bronchoscopy in Diagnosis of Active Pulmonary Tuberculosis

Na, Moon Jun

Abstract

OBJECTIVE
Expectorated sputum examination applied first in all patients with suspected pulmonary tuberculosis is low sensitivity. Bronchoscopy is applied next in patients with smear negative sputum. In some instances, bronchoscopy can not be available in patients because of poor conditions or cooperations. The aim of this study was to determine whether sputum induction is more simple and more convenient method than bronchoscopy or not to diagnose pulmonary tuberculosis in AFB smear-negative patients.
METHODS
The objects of this study were 47 patients whose smear results of expectorated sputum were negative or could not produce expectorated sputum. Consecutive patients underwent sputum induction with 3% hypertonic saline delivered by ultrasonic nebulizer at least 24 hour before bronchial washing by fiber-optic bronchoscopy. All specimens were examined for acid-fast bacilli with Ziehl-Neelsen stain and cultured for mycobacteria.
RESULTS
1) Sensitivity of AFB smear were 36% (17/47) in induced sputum, 53%(25/47) in bronchoscopy, but statistically not significant(p>0.05). 2) Sensitivity of mycobacterial culture were 53%(25/47) in induced sputum, 68%(32/47) in bronchoscopy, statistically not significant(p>0.05). 3) Positive AFB smear in endobronchial tuberculosis(n=9) were 5 in induced sputum, and 9 in bronchoscopy. 4) In 10 patients who were not obtainable sputum initially, AFB smear were positive in 7 in induced sputum and 9 in bronchoscopy 5) In 11 patients who cultured in expectorated sputum later, positive culture were 10 patients both in induced sputum and bronchoscpy. 6) All 5 patients who didn't undergo bronchoscopy were positive AFB smear in induced sputum
CONCLUSION
In suspected active pulmonary tuberculosis patients with negative AFB smear of expectorated sputum, induced sputum does not replace bronchoscopy to diagnose active pulmonary tuberculosis. But, sputum induction is useful diagnostic method to detect mycobacteria before or in not available bronchoscopy.