Rapid blood tests help detect latent TB.3 They can help diagnose TB when results from a tuberculin skin test are uncertain. These tests also can tell if a person who has had a BCG vaccination has a TB infection. A rapid test requires only one visit to the doctor or clinic, instead of two visits as required for the tuberculin skin test. Rapid blood tests are also called interferon-gamma release assays (IGRAs).
Diagnosing TB outside the lungs
Diagnosing TB in other parts of the body (extrapulmonary TB) requires more testing. Tests include:
BiopsyBiopsy. A sample of the affected area is taken out and sent to a lab to look for TB-causing bacteria.