Table 1.
Commonly used laboratory tests for extrapulmonary tuberculosis.
| Test | Sensitivity | Time taken | Remarks |
|---|---|---|---|
| AFB staining | 10–30% | – | Non tubercular bacteria may stain similarly |
| Conventional solid media (LJ) | 30–80% | 6–8 weeks | Gold standard |
| Mycobacterial Growth Indicator tube (MGIT) 960 | 97% | 2–4 weeks | Gold standard |
| Histopathology | 72–97% | Tissue processing required | Gold standard |
| Interferon gamma release assay: QuantiFERON –TB; T SPOT | 60–83% | 24 h | Indicate cellular response to specific microbial antigens. ATT based on these tests is not warranted. |
| Molecular analysis e.g. PCR, Xpert MTB/RIF assay | 61–83% | 24 h | Extraction and amplification of target gene and DNA. ATT based on PCR is investigational and clinical/histopathology correlation is advised |