The diagnostic yield of prebronchoscopy sputa and bronchial washings in patients with biopsy-proven pulmonary tuberculosis.

We report on a series of 35 patients with pulmonary tuberculosis diagnosed by flexible fibre-optic bronchoscopy and transbronchial lung biopsy after 3 sputum specimens had been microscopy-negative. This study re-evaluates this invasive procedure. Additional prebronchoscopy specimens of expectorated sputum yielded the diagnosis in 7 of 16 cases (43.8%) on microscopy. Sputum culture results were positive in 12 of 33 (36.4%). Pleural fluid culture was diagnostic in 1 case, and in another miliary tuberculosis was demonstrated on bone marrow trephine biopsy. The availability of these results could therefore have obviated the need for bronchoscopy in 14 of the 35 patients (40%). Bronchial washings were positive for acid-fast bacilli on microscopic examination in 13 of 34 cases (38.2%) and culture-positive in only 18 of 34 (52.9%), and should therefore not be the sole procedure utilised when bronchoscopy is performed. Transbronchial lung biopsy remains a valuable procedure to confirm pulmonary tuberculosis in patients whose sputum is culture-negative for mycobacteria.