how long does it take to do a tb test

2 min read 31-12-2024

Meta Description: Wondering how long a TB test takes? This comprehensive guide details the different types of TB tests, their procedures, and the time it takes to get results. Learn about the Mantoux test, IGRA blood tests, and more! Get informed about tuberculosis testing timelines and what to expect.

What is a TB Test?

A tuberculosis (TB) test, also known as a tuberculin skin test (TST) or Mantoux test, checks if you've been infected with the bacteria that cause TB. It doesn't tell if you have active TB disease, only if you've been exposed. There are different types of TB tests, and the time it takes to get results varies.

Types of TB Tests and Their Timelines

There are two main types of TB tests:

1. Tuberculin Skin Test (TST) or Mantoux Test

Procedure: A small amount of tuberculin is injected just under the skin of your forearm.
Time to Read Results: You'll need to return 48-72 hours later for a healthcare professional to check for a reaction (a raised, hard bump). The size of the bump determines the interpretation. It doesn't take long for the injection itself.

2. Interferon-Gamma Release Assays (IGRAs) – Blood Tests

Procedure: A blood sample is taken.
Time to Read Results: Results are usually available within 24-72 hours, sometimes faster depending on the lab. IGRAs are becoming increasingly common due to their speed and accuracy. The blood draw itself takes only a few minutes.

3. Chest X-Ray

While not a direct TB test for infection, a chest X-ray may be ordered if a positive skin test or blood test result is obtained. This helps determine if active TB disease is present.

Procedure: A simple X-ray of your chest.
Time to Read Results: Results are typically available within a few hours to a few days, depending on the facility and workload.

Factors Affecting Test Timelines

Several factors can influence how long it takes to get your TB test results:

Lab Processing Times: Labs have varying workloads. This can affect how quickly results are processed, especially for blood tests.
Healthcare Provider Availability: Scheduling an appointment to get the test read (for the TST) or follow up on your blood test results can add time to the overall process.
Test Type: Blood tests (IGRAs) generally provide results faster than the TST.

What to Expect During and After a TB Test

The actual procedure for both types of tests is relatively quick. The Mantoux test involves a simple injection, and the IGRA is a standard blood draw. Discomfort is minimal.

After the Mantoux test, avoid scratching or rubbing the injection site. For both tests, follow your healthcare provider's instructions carefully. They will advise you when and how to get your results.

Understanding Your Results

It's crucial to discuss your results with a healthcare provider. A positive result doesn't automatically mean you have active TB disease. Further testing and evaluation might be necessary.

Conclusion

The time it takes to complete a TB test and get results varies depending on the test type and other factors. While the actual procedure is quick, remember to factor in the time needed for results processing and follow-up appointments. A healthcare professional will guide you through the entire process and help interpret your results. If you have concerns about tuberculosis, don't hesitate to contact your doctor.