Tuberculosis, or TB for short, is an infectious disease that can be potentially serious, primarily affecting the lungs. It is transmitted from person to person through droplets containing the bacteria that are released when an infected person coughs or sneezes. While not a common disease, it is still one of concern in the United States. There are several test options to determine if a person has TB. Your doctor will want to first and foremost perform a physical exam, including a check for swelling of the lymph nodes and listening to the lungs through a stethoscope. From there, the most common test used to test for TB is typically a skin test where a substance called tuberculin is injected on the inside of your forearm, below the skin. Within 72 hours, the spot will need to be checked by a healthcare professional; if there is a red, hard lump, it indicates that you likely have TB. Additional tests may be needed to confirm if the patient does have TB. A blood test can determine the presence of latent or active tuberculosis, and how your immune system reacts to the TB bacteria. A chest x-ray or CT scan may also be requested to check the lungs for signs of TB. The final test that can be performed is a sputum test, in which the mucus that is expelled from coughing is tested for the presence of TB bacteria. This test is also used to help your doctor to determine which medications to prescribe, as it can reveal strains of TB that are resistant to certain medications.