Saturday, February, 11, 2012

Pneumonia - Diagnosis

Table of Contents

X-rays are a form of electromagnetic radiation (like light). They are of higher energy, however, and can penetrate the body to form an image on film. Structures that are dense (such as bone) will appear white, air will be black, and other structures will be shades of gray depending on density. X-rays can provide information about obstructions, tumors, and other diseases, especially when coupled with the use of barium and air contrast within the bowel.

A chest x-ray may reveal the following:

  • Complications of pneumonia, including pleural effusions and abscesses
  • White areas in the lung called infiltrates, which indicate infection

Other Imaging Tests. Computed tomography (CT) scans or magnetic resonance imaging (MRI) scans may be useful in some circumstances, especially when:

  • A lung tumor is suspected
  • Complications occur
  • Patients do not respond to antibiotics
  • Patients have other serious health problems
  • Pulmonary embolism is suspected
  • X-ray results are unclear
Click the icon to see an image of a CT scan.

CT and MRI can help detect tissue damage, abscesses, and enlarged lymph nodes. They can also detect some tumors that block bronchial tubes. No imaging technique can determine the actual organism causing the infection. However, features on the CT scan of patients with certain forms of pneumonia -- for example, that caused by Legionella pneumophila -- are usually different from features produced by other bacteria in the lungs.

Invasive Diagnostic Procedures

Invasive diagnostic procedures may be required when:

  • AIDS or other immune problems are present
  • Patients have life-threatening complications
  • Standard treatments have failed for no known reason

Invasive procedures include:

Thoracentesis. If a doctor detects pleural effusion during the physical exam or on an imaging study, and suspects that pus (empyema) is present, a thoracentesis is performed.

  • Fluid in the pleura is withdrawn using a long thin needle inserted between the ribs.
  • The fluid is then sent to the lab for multiple tests.

Complications of this procedure are rare, but can include collapsed lung, bleeding, and infection.

Review Date: 04/13/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)