EC Pulmonology and Respiratory Medicine

Background: The World Health Organization reported 10.1 million cases of tuberculosis in 2022, of which 17% were extrapulmonary TB (EPTB). Because of diverse clinical characteristics and difficulty in extracting a sample from tissues, clinicians face some challenges in the diagnosis. Laboratory diagnosis is also difficult due to the paucibacillary or smear-negative specimens. This study was undertaken to determine the diagnostic yield of Truenat-MTB-polymerase chain reaction (PCR) in EPTB.

Objectives: To determine the diagnostic yield of Truenat in patients who are clinically diagnosed as having EPTB and presenting to a tertiary care center.

Study Design: Prospective observational study on all patients with presumptive EPTB attending a tertiary care hospital. Patients with established pulmonary tuberculosis were excluded. Sample collected from all suspected EPTB patients will be sent for Truenat, AFB culture, and histopathological studies. The clinical, radiological, laboratory, and other relevant data from patients will be collected from direct interaction with patients and from medical records using a structured study proforma. These data will be entered into Microsoft Excel and analysed using appropriate tools.

Results: The combination of Truenat with AFB culture exhibited moderate sensitivity (58.18%) and high specificity, with an overall accuracy of 60.00%. Adding HPE to Truenat significantly improved diagnostic accuracy, yielding a sensitivity of 91.84% and 100% specificity, but still had a moderate NPV (33.33%). The most comprehensive diagnostic approach, combining Truenat with both HPE and AFB culture, achieved the highest sensitivity (96.46%) and accuracy (95.76%), albeit with moderate specificity (80.00%) and an NPV of 50.00%, indicating some false negatives.

Conclusion: Combinations involving Truenat, HPE, and AFB culture significantly enhanced diagnostic accuracy and sensitivity, the inherent limitations in NPV suggest that negative results should be interpreted cautiously, underscoring the necessity for a multifaceted diagnostic approach to reliably diagnose EPTB.

 Keywords: Extrapulmonary Tuberculosis; Truenat MTB PCR; Histopathology; AFB Culture

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