Diagnosing sputum smear negative pulmonary tuberculosis patients by transbronchial biopsy and bronchoalveolar lavage smear.

Pulmonary tuberculosis is one of the leading causes of infectious disease related mortality. Transbonchial biopsy and bronchoalveolar lavage smear obtained by bronchoscopy provides greater quantity of material for analysis, thus increases the chances of diagnosing the disease. Objectives: To diagnose sputum smear negative pulmonary tuberculosis patients by Transbronchial Biopsy and Bronchoalveolar smear keeping bronchoalvelar lavage culture as gold standard. To calculate and compare the diagnostic accuracy of transbronchial biopsy and bronchoalveolar lavage smear in sputum negative patients. Study Design: Cross-sectional validation study. Setting: Department of histopathology, Foundation University Medical College, Islamabad and Department of Pulmonology and Microbiology, Fauji Foundation Hospital, Rawalpindi. Period: From May 2016 to May 2017. Materials & Methods: It comprised 96 patients who underwent bronchoscopy. Transbronchial biopsy, bronchoalveolar lavage smear preparation and bronchoalveolar lavage culture was performed on specimens of all patients. Results: Out of 96 patients 22 (22.91%) patients were actually having tuberculosis whereas 74 (77%) had only clinical and radiological suspicion of tuberculosis. The mean age of patients was 43 years with a standard deviation of ±19.1 .The age range was 12-80 years. The sensitivity, specificity, positive predictive value, negative predictive value and true positives of transbronchial biopsy were 68.1%, 77%, 46.8%, 89% and15.62% while the values for bronchoalveolar lavage were 50%, 97.29%, 84.6%, 86.7% and 11.45% respectively. Thus, the diagnostic accuracy calculated for transbronchial biopsy and bronchoalveolar lavage was 75% and 13.54% respectively. Conclusions: Bronchoscopy should be done in all sputum negative tuberculosis patients having strong clinical and radiological suspicion to obtain transbronchial biopsy and bronchoalveolar lavage for timely diagnosis, treatment and prevention of disease transmission as well as to avoid empirical treatment and its side effects in patients having no tuberculosis. The diagnostic accuracy of transbronchial biopsy is almost 5 times more compared to bronchoalveolar lavage smear.