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Health Information Center

Diagnosis of Pneumonia

  • Cynthia M. Johnson, MA
Publication Type:

Condition InDepth

Diagnosis of Pneumonia

The doctor will ask about symptoms and past health. You may also be asked questions about any recent travel history or exposures to sickness. The doctor will tap on your chest and back. This may point to fluid or air trapped in your lungs. The doctor will also listen carefully to your chest and back with a stethoscope.

Tests may include:

  • Blood tests—A complete blood count will be done that includes the number and types of white blood cells. This may help find out whether the infection is viral, bacterial, or fungal.
  • Blood culture—A blood sample will be sent to a lab to be processed to see if any organisms are growing. If so, they can often be identified, and tests can be run to find out what types of antibiotics would work best against them.
  • Arterial blood gas —To measure substances in the blood, such as oxygen, carbon dioxide, and pH. This test may be done to find out whether you will be able to keep breathing on your own or whether you may needoxygen therapy or mechanical ventilation.
  • Urine antigen tests—A urine sample can help find bacteria that could be causing the infection.
  • Rapid antigen and PCR tests—A sample from the nasopharynx can help identify COVID and influenza viruses.
  • Pulse oximetry—A device is lightly clamped to the end of your finger to measure the amount of oxygen in the blood.
  • Sputum culture—If you are able to cough up a sample of sputum, it can be sent to a lab to look for organisms. If they can be identified, they may be treated medicine.
  • Thoracentesis—A needle is passed through the chest, back, or between the ribs to collect excess fluid from the chest cavity. This fluid can be sent to a lab to look for organisms.
  • Bronchoscopy—A narrow, lighted scope is passed through the mouth or nose, down the bronchial tubes, and into the lungs to look for signs of pneumonia. Samples of fluid and biopsies of tissue can be taken through the scope. These samples can sent to a lab to try to look for organisms that might be causing pneumonia.

Pictures will be taken of the lungs and surrounding tissues to look for signs of pneumonia. This can be done with:


  • Community-acquired pneumonia in adults. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/community-acquired-pneumonia-in-adults.
  • Community-acquired pneumonia in children. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/community-acquired-pneumonia-in-children.
  • COVID-19: How to protect yourself and others. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html.
  • Pneumonia. American Lung Association website. Available at: https://www.lung.org/lung-health-diseases/lung-disease-lookup/pneumonia.
  • What is pneumonia? National Heart, Lung, and Blood Institute website. Available at: https://www.nhlbi.nih.gov/health/pneumonia.


  • David L. Horn, MD, FACP
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.