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Transbronchial cryobiopsy in diagnosis of smear-negative pulmonary tuberculosis: validity and safety

Background Smear-negative pulmonary tuberculosis (PTB) represents 42% of PTB cases and is responsible for ∼20% of tuberculosis (TB) transmission cases. Early recognition of TB cases is important to limit TB transmission. This study was planned to assess validity and safety of bronchoscopic transbronchial cryobiopsy in diagnosis of patients with smear-negative PTB. Patients and methods Patients with smear-negative PTB were enrolled. Bronchoalveolar lavage (BAL) and transbronchial cryobiopsy were taken. BAL was sent for microbiological examination (Ziehl–Neelsen for acid-fast bacilli and TB culture). Results A total of 24 patients were included in the study. BAL Ziehl–Neelsen staining result was positive in four (16.7%) patients, and TB culture finding was positive in five (20.8%) patients. Among those who had a positive cryobiopsy result, the probability of TB disease was 100% (no false-positive results). Among those who had a negative cryobiopsy result, the probability of being TB free was 89.5%. So, sensitivity of transbronchial cryobiopsy in diagnosis of pulmonary TB was 85% and specificity was 100%. Conclusion Transbronchial lung cryobiopsy is rapid and safe procedures in diagnosis of smear-negative pulmonary TB. However, further studies on a large number of patients are recommended.