Role of Fiberoptic Bronchoscopy in Patients With Sputum-Negative and Clinico-Radiological Suspicious Pulmonary Tuberculosis

Tuberculosis (TB) remains a major global public health concern, particularly in high-burden countries such as India. Pulmonary TB (PTB) is the most common form of the disease and the principal source of transmission. Although sputum smear microscopy using Ziehl-Neelsen (ZN) staining is widely employed for diagnosis, it has limited sensitivity, especially in patients with sputum smear-negative disease. These patients often present with strong clinical symptoms and radiological findings suggestive of PTB but lack microbiological confirmation, leading to diagnostic delay, inappropriate empirical therapy, and continued transmission. In this context, fiberoptic bronchoscopy (FOB) with bronchoalveolar lavage (BAL) offers an important diagnostic alternative by enabling direct airway evaluation and targeted sample collection. The use of molecular diagnostics, such as the cartridge-based nucleic acid amplification test (CBNAAT) on BAL samples, has further enhanced diagnostic yield. This cross-sectional observational study was conducted over 18 months at the Department of Pulmonary Medicine at L.N. Medical College and J.K. Hospital, Bhopal. Adult patients (≥18 years) with clinical features suggestive of PTB, such as cough, fever, weight loss, night sweats, or hemoptysis, and radiological findings consistent with PTB, but with at least two sputum samples negative for acid-fast bacilli (AFB) on ZN staining, were included. Patients with prior anti-tubercular therapy within six months, sputum-positive TB, pregnancy, or contraindications to bronchoscopy were excluded. A total of 97 patients were included. All patients underwent detailed clinical evaluation, chest imaging, and FOB performed under standard aseptic precautions. BAL samples were collected from radiologically involved lung segments and subjected to AFB smear microscopy and CBNAAT. Statistical analysis was performed to assess associations between clinical features, radiological findings, and BAL-CBNAAT results. The mean age of the study population was 48.98 ± 16.37 years. Almost all patients (95/97; 97.9%) were symptomatic, with cough (88/97; 90.7%) and fever (83/97; 85.6%) being the most common presenting complaints, followed by weight loss (77/97; 79.4%) and night sweats (56/97; 57.7%). Hemoptysis was infrequent (5/97; 5.2%). All patients had radiological findings suggestive of PTB as per the inclusion criteria. BAL-AFB smear was negative in all cases, highlighting the limited sensitivity of smear microscopy in sputum-negative disease. In contrast, BAL-CBNAAT detected Mycobacterium TB in 89 of 97 patients, yielding a diagnostic positivity rate of 91.75%. A statistically significant association was observed between BAL-CBNAAT positivity and clinical symptoms such as cough, fever, weight loss, and night sweats (p < 0.05), while hemoptysis showed no significant correlation. The study concludes that FOB with BAL, when combined with CBNAAT, has a high diagnostic yield in sputum smear-negative patients with clinico-radiological suspicion of PTB. This approach effectively overcomes the limitations of sputum-based diagnostics, enables early microbiological confirmation, and facilitates timely initiation of appropriate therapy. FOB should be considered a crucial diagnostic tool in the evaluation of sputum smear-negative PTB.