Topic Overview

Other tests for lung infections, such as pneumonia and acute bronchitis, may include:

• Blood tests or cultures. Blood tests may help determine whether antibodies to a specific organism that can cause pneumonia are present or whether specific viruses, such as influenza (flu) or respiratory syncytial virus (RSV), are present. A test for blood urea nitrogen (BUN) can help tell how serious an infection is. Doctors can use blood cultures to test for bacteria in your bloodstream.
• Oximetry. An oximeter can estimate the amount of oxygen in your blood. A sensor in a cuff or clip is placed on the end of your finger. This sensor determines how much oxygen is in your blood. The oximeter machine shows the result.
• Arterial blood gases. An arterial blood gas test can measure the levels of oxygen in a sample of blood drawn from your artery. Doctors use this test to find out whether enough oxygen is getting into your bloodstream from your lungs.
• Bronchoscopy. Bronchoscopy is a visual exam of the tubes leading to your lungs. This test is usually done by a pulmonologist (lung specialist). He or she inserts a small, lighted device through your nose or mouth into the tubes leading to your lungs. During the procedure, the doctor can obtain samples of tissue, fluid, or sputum (mucus).
• Transtracheal sputum cultures (rarely done). Transtracheal sputum cultures are tests performed on a mucus sample obtained directly from your windpipe (trachea).
• Lung biopsy. A lung biopsy is a test done on a very small piece of lung tissue to look for conditions such as lung cancer or fibrous tissue in the lungs (pulmonary fibrosis). Your doctor obtains lung tissue by inserting a needle into your chest between two ribs or by using bronchoscopy.
• Thoracentesis. Thoracentesis involves puncturing the chest wall to obtain fluid from the space around the lungs. Fluid obtained during the test can be checked for signs of infection or cancer.
• Computed tomography (CT) scan. A CT scan uses X-rays to produce detailed pictures of structures inside your body. It may be used in people who are not responding to their treatment.