[Comparison of sputum induction and bronchoalveolar lavage methods in diagnosis of pulmonary TB in patients with negative smear or without spontaneous sputum]

ABSTRACT

Sputum smear is recommended for microbiological confirmation of diagnosis of pulmonary tuberculosis. It has been reported that sputum induction is a safe and non-invasive method for confirmation of microbiological diagnosis of tuberculosis in smear negative patients. This study deals with the comparison of the value of sputum induction with that of bronchoalveolar lavage [BAL] in the diagnosis of TB. 56 patients suspected to have tuberculosis were admitted in the infectious ward of Tohid Hospital and entered into this study. Sputum induction and BAL were performed for two consecutive days according to a standard procedure. Smears obtained from induced sputum and BAL contents were stained for acid fast bacilli. Exclusion criteria were severe asthma or severe chronic obstructive pulmonary disease and pregnancy. Of 56 tuberculosis suspects with negative or absent sputum production, sputum induction led to positives smears in 8 [14.3%] patients [5 previously smear-negative, 3 unproductive] and BAL had positive results in 7 [12.5%] patients which revealed a significant difference [p = 0.000]. Sputum induction is safer, easier to accomplish and more sensitive than BAL technique for diagnosis of pulmonary TB. Our study suggests that sputum induction with aerosolized hypertonic saline is a useful technique for better detection of cases of tuberculosis in patients with negative smears or non-productive cough