Sputum Gram stain

• Alternative Names

  Gram stain of sputum

• How the test is performed

  A sputum sample is needed. You will be asked to cough deeply and spit any material that comes up from your lung into a special container. If this does not work, you may receive a breathing treatment before the test to help you produce the sample. If you have a dry cough or are unable to produce a sample, a bronchoscopy may be necessary.

  The sample is sent to a lab. The lab team member places a very thin layer of the sample onto a glass slide -- this is called a smear. A series of special stains is applied to the sample. The lab team member looks at the stained slide under a microscope, checking for bacteria and white blood cells. The color, size, and shape of the cells help identify the infecting organism.

• How to prepare for the test

  No preparation is usually needed, unless a bronchoscopy is necessary.

• How the test will feel

  How the test will feel depends on the method used to produce the sample. More discomfort is associated with a bronchoscopy.

• Why the test is performed

  Your doctor may order this test if you have a persistent or prolonged cough, or if you are coughing up material that has a foul odor or unusual color. The test may also be done if you have other signs and symptoms of respiratory disease or infection.

• Normal Values

  A normal result means that few to no white blood cells and no bacteria were seen in the sample. The sputum is clear, thin, and odorless.

  Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

• What abnormal results mean

  An abnormal results means that infection-causing organisms are present in the sample. This is a sign that a bacterial infection may be present. A sputum culture is needed to confirm the diagnosis.

• What the risks are

  There are no risks associated with coughing up a sample. See the article on bronchoscopy for information regarding risks related to that procedure.

• Special considerations

  The test may need to be repeated if the sample contains only saliva from the mouth.

• References

  Mandell LA. Pneumococcal pneumonia. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 311.

Review Date: 12/3/2007

Reviewed By: D. Scott Smith, M.D., MSc, DTM&H, Chief of Infectious Disease & Geographic Medicine, Kaiser Redwood City, CA & Adjunct Assistant Professor, Stanford University. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.