Tests and diagnosis

By Mayo Clinic Staff

Your doctor will start by asking about your medical history and doing a physical exam, including listening to your lungs with a stethoscope to check for abnormal bubbling or crackling sounds that indicate the presence of secretions.

If pneumonia is suspected, your doctor may recommend the following tests:

  • Chest X-ray. This helps your doctor diagnose pneumonia and determine the extent and location of the infection. However, it can't tell your doctor what kind of germ is causing the pneumonia.
  • Blood tests. Blood tests are used to confirm infection and to try to identify the type of organism causing the infection. However, precise identification isn't always possible.
  • Pulse oximetry. This measures the oxygen level in your blood. Pneumonia can prevent your lungs from moving enough oxygen into your bloodstream.
  • Sputum test. A sample of fluid from yourlungs (sputum) is taken after a deep cough and analyzed to help pinpoint the cause of the infection.

Your doctor might order additional tests if you're older than age 65, are in the hospital, or have serious symptoms or health conditions. These may include:

  • Pleural fluid culture. A fluid sample is taken by putting a needle between your ribs from the pleural area and analyzed to help determine the type of infection.
  • CT scan. If your pneumonia isn't clearing as quickly as expected, your doctor may recommend a chest CT scan to obtain a more detailed image of your lungs.
March 14, 2015

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