Which test is used to confirm a diagnosis of active Tuberculosis?

The confirmation of active Tuberculosis (TB) is primarily achieved through a sputum culture. This test involves collecting a sample of sputum (the mucus produced in the respiratory tract) and sending it to a laboratory for culture. The laboratory can grow the bacteria if they are present, thus providing a definitive diagnosis of active TB.

While other tests, such as chest X-rays and skin tests (Tuberculin skin test), can provide important information regarding TB infection status, they are not definitive in confirming an active case. For instance, an X-ray can show changes in the lungs that suggest TB, but it cannot distinguish between active and inactive disease without follow-up cultures. Similarly, a skin test can indicate whether someone has been exposed to TB, but it does not confirm active disease.

Blood tests, like the Interferon Gamma Release Assays (IGRAs), also help in diagnosing TB infection but have limitations concerning the distinction between latent and active TB. Therefore, the sputum culture remains the gold standard for confirming active Tuberculosis.