Your doctor will ask about your symptoms. If symptoms suggest pneumonia, your doctor will ask about your medical history, travel history, and other related exposures. A physical exam usually includes tapping on your chest and back. This may identify the presence of fluid or air trapped in your lungs. The doctor will also listen carefully to your chest and back with a stethoscope.
Your doctor may choose to order a variety of tests, such as:
- Blood tests —Complete blood count including the number and types of white blood cells. This may help determine whether the infection is viral, bacterial, or fungal in nature.
- Blood culture —This involves sending a blood sample to a laboratory where it can be processed to see if any organisms are growing. If there are organisms, they can often be identified, and tests can be run to determine what types of antibiotics can best eliminate them.
- Arterial blood gas —To measure the concentration of certain substances in your blood, including oxygen, carbon dioxide, and pH. This test may be performed to determine whether you will be able to continue breathing on your own, or whether you may need treatment with additional oxygen therapy or mechanical ventilation.
- Urine antigen tests —A urine sample can help with identifying certain bacteria that could be causing the infection.
- Pulse oximetry —This test measures the amount of oxygen in your blood. A device is lightly clamped to the end of your finger.
- Sputum culture —If you’re able to cough up a sample of sputum, it can be sent to a laboratory to examine it for the presence of specific organisms. If organisms in the sputum can be identified, they may be treated with a drug.
- Thoracentesis —A needle can be passed through the chest, back, or between the ribs in order to withdraw excess fluid in the chest cavity. This fluid can be examined in a laboratory to identify organisms responsible for the pneumonia.
- Bronchoscopy —A narrow, lighted scope is passed through your mouth or nose, down your bronchial tubes, and into your lungs. Your doctor can examine your respiratory tract for signs of pneumonia. Samples of fluid and biopsies of tissue can be taken through the bronchoscope. These samples can be processed and examined in a laboratory to try to identify organisms that might be causing pneumonia.
Imaging tests are used to evaluate the lungs and surrounding tissues. Pneumonia may be detected through imaging, though there are times when it may not show up.
Canadian Critical Care Trials Group. A randomized trail of diagnostic techniques for ventilator-associated pneumonia. N Engl J Med. 2006;355(25):2619-2630.
Community-acquired pneumonia in adults. EBSCO DynaMed website. Available at:http://www.dynamed.com/topics/dmp~AN~T115170/Community-acquired-pneumonia-in-adults. Accessed November 10, 2020.
Community-acquired pneumonia in children. EBSCO DynaMed website. Available at:http://www.dynamed.com/topics/dmp~AN~T113670/Community-acquired-pneumonia-in-children. Accessed November 10, 2020.
Diagnosis. National Heart, Lung, and Blood Institute website. Available at: http://www.nhlbi.nih.gov/health/health-topics/topics/pnu/diagnosis. Accessed November 10, 2020.
Diagnosing and treating pneumonia. American Lung Association website. Available at: http://www.lung.org/lung-health-and-diseases/lung-disease-lookup/pneumonia/diagnosing-and-treating.html. Accessed November 10, 2020.
Lutfiyya MN, Henley E, Chang LF, Reyburn SW. Diagnosis and treatment of community-acquired pneumonia. Am Fam Physician. 2006;73(3):442-450.
Mayer J. Laboratory diagnosis of nosocomial pneumonia. Semin Respir Infect. 2000;15(2):119-131.
Murphy, CG, van de Pol, Harper MB, Bachur RG. Clinical predictors of occult pneumonia in the febrile child. Acad Emerg Med. 2007;4:(3)243-249.
Last reviewed January 2020 by EBSCO Medical Review Board David L. Horn, MD, FACP Last Updated:1/21/2020