To Study the Diagnostic Yield of CBNAAT In Diagnosis of Tubercular Pleural Effusion in a Tertiary Care Centre

Background: Tubercular pleural effusion (TPE) is one of the most common forms of extrapulmonary tuberculosis in high-burden countries like India. Its diagnosis is challenging due to the paucibacillary nature of pleural fluid, limiting the utility of conventional methods such as smear microscopy and culture. The Cartridge-Based Nucleic Acid Amplification Test (CBNAAT/Xpert MTB/RIF) offers rapid detection of Mycobacterium tuberculosis (MTB) and rifampicin resistance, but its diagnostic yield in pleural fluid remains variable. Objectives: To evaluate the diagnostic yield of CBNAAT in pleural fluid samples of patients with suspected TPE and to study its association with ADA levels and cytological findings. Materials and Methods: This hospital-based cross-sectional observational study was conducted at PGIMER and Capital Hospital, Bhubaneswar, over 12 months (May 2024 – April 2025). A total of 150 patients with clinically and radiologically diagnosed pleural effusions were included. Detailed clinical assessment, chest radiography, blood tests, and pleural fluid analysis (biochemical, cytology, ADA, AFB smear, and CBNAAT) were performed. Data were analyzed using SPSS v21, with diagnostic yield expressed in terms of positivity rates. Results: Among 150 patients, the mean age was 42.8 ± 15.6 years, with male predominance (65.3%). The most common symptoms were dyspnea (93.3%) and fever (80%). Pleural fluid analysis revealed lymphocytic predominance in 94.7% and ADA ≥ 40 U/L in 92%. CBNAAT was positive in 30% of patients, while AFB smear showed positivity in only 3.3%. Rifampicin resistance was detected in 2% of cases. Most CBNAAT-positive cases also had high ADA and lymphocyte predominance. Conclusion: CBNAAT demonstrated a moderate diagnostic yield (30%) in pleural fluid but provided high specificity and rapid detection of rifampicin resistance, making it a valuable adjunct in diagnosing TPE. When used alongside ADA and cytology, CBNAAT enhances diagnostic accuracy and facilitates the timely initiation of appropriate therapy in high-burden settings.