How Is Pneumonia Diagnosed?

Pneumonia can be hard to diagnose because it may seem like a cold or the flu. People may not realize it’s more serious until it lasts longer than these other conditions.

Your doctor will diagnose pneumonia based on your medical history and the results from a physical exam and tests.

Medical History

Your doctor will ask about your signs and symptoms and how and when they began. To find out what type of germ is causing the pneumonia, he or she also may ask about:

• Any recent traveling you’ve done
• Your hobbies
• Your exposure to animals
• Your exposure to sick people at home, school, or work
• Your past and current medical conditions, and whether any have gotten worse recently
• Any medicines you take
• Whether you smoke
• Whether you've had a flu or pneumonia vaccination

Physical Exam

Your doctor will listen to your lungs with a stethoscope. If you have pneumonia, your lungs may make crackling, bubbling, and rumbling sounds when you inhale. It may be hard to hear sounds of breathing in some areas of your chest. Your doctor also may hear wheezing.

Diagnostic Tests

If your doctor suspects you have pneumonia, he or she also may order one or more of the following tests.

Chest X Ray

A chest x ray is a painless test that creates pictures of the structures inside your chest, such as your heart and lungs.

A chest x ray is the best test for diagnosing pneumonia. However, this test won’t tell your doctor what kind of germ is causing the pneumonia.

Blood Tests

Blood tests involve taking a sample of blood from a vein in your body. A complete blood count (CBC) measures many parts of your blood, including the number of white blood cells in the blood sample. The number of white blood cells can show whether you have a bacterial infection.

Your doctor also may order a blood culture to find out whether the infection has spread to your bloodstream. This test is used to detect germs in the bloodstream. It may show which germ caused the infection. If so, your doctor can decide how to treat the infection.

Other Tests

You may need other tests if you’re in the hospital, have serious symptoms, are older, or have other health problems.

Sputum test. Your doctor may look at a sample of sputum (spit) collected from you after a deep cough. This may help your doctor find out what germ is causing your pneumonia . Then, he or she can plan treatment.

Chest CT scan. A chest CT scan is a painless test that creates precise pictures of the structures in your chest, such as your lungs. A chest CT scan is a kind of x ray, but its pictures show more detail than those of a standard chest x ray.

Pleural fluid culture. For this test, a sample of fluid is taken from the space between your lungs and chest wall (the pleural space). This is done using a procedure called thoracentesis (THOR-a-sen-TE-sis). The fluid is studied for germs that may cause pneumonia.

Pulse oximetry. For this test, a small clip is attached to your finger or ear to show how much oxygen is in your blood. Pneumonia can keep your lungs from moving enough oxygen into your bloodstream.

If you’re very sick, your doctor may need to measure the level of oxygen in your blood using a blood sample. The sample is taken from an artery, usually in your wrist.

Bronchoscopy. Bronchoscopy (bron-KOS-ko-pee) is a procedure used to look inside the lungs' airways. If you’re in the hospital and treatment with antibiotics isn’t working well, your doctor may use this test.

Your doctor passes a thin, flexible tube with a camera on its tip through your nose or mouth, down your throat, and into the airways.

This test allows your doctor to see whether something is blocking your airways or whether another factor is contributing to your pneumonia.