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Cytology, Sputum

Pronounced: sie-taw-lodj-ee, spew-tum

What Is Sputum?

Sputum is mucous made by the lungs. It can be found deep in your airways. It contains lung tissue cells and other substances found in the lungs. It may be coughed up when you are ill.

Reason for the Test

This test may be done to find out whether there are cancer cells in your sputum. It may also be done to look for specific infections. It may be don in people who have lung cancer to see if the cancer is improving or coming back.

Using this test as a screening tool for lung cancer is not advised. Such screening does not appear to improve survival.

Type of Sample Taken

A sample of sputum will be collected. Usually it is collected after deep coughing to bring cells up from your lungs.

Sputum may also be collected during a bronchoscopy. This is a test in which a lighted tube is used to view the airways.

Prior to Collecting the Sample

Clean your mouth before producing a sample by coughing.

If you are having a bronchoscopy:

  • You may need to stop taking some medicine before the procedure. Talk to your doctor about the medicines you take.
  • Arrange for a ride to and from the procedure.
  • Do not eat or drink anything after midnight the night before the procedure.

During the Sample Collection

You may be asked to breathe a humid vapor to help you to cough up sputum.

If you are able to produce enough sputum through coughing:

  • You will be given three sterile containers.
  • Cough sputum into a new container each morning for three mornings in a row.
  • Seal and return the samples to the doctor’s office or lab.

If you cannot produce enough sputum through coughing, your doctor may do a bronchoscopy:

  • Take deep breaths and do not talk during the procedure.
  • You will be given a medicine to numb your throat and prevent coughing and gagging. Sometimes, a bronchoscopy is done under a general anesthetic.
  • A long, thin tool called a bronchoscope is passed through your nose or mouth, down the throat, and into the lungs.

Cytology is the study of cells in a sample. Some of your sputum will be smeared on a slide and studied under a microscope.

The procedures often take less than 1 hour.

After Collecting the Sample

There are no side effects to coughing sputum up.

If you had a bronchoscopy:

  • Spit out saliva. Do not try to swallow it while your throat tissues are numb.
  • Do not eat or drink anything for 2 hours. Your throat muscles will still be numb.
  • When you are able to eat, start with sips of water. Move on to solid food as you are able.
  • If you had a biopsy, try not to cough. If you must, do it gently for the first 24 hours.
  • A chest x-ray is usually done before you go home.
  • Do not drive until the sedative has fully worn off and you are awake.
  • Resume medicines as instructed by your doctor.
  • Go back to your normal diet, unless the doctor has told you not to.

People who have general anesthesia may have some neck soreness for a few days.


It may take one to several days to get your results. It depends on how the sample was collected, where it was tested, and the health problem you may have.

It may take longer to get the results of samples being looked at for lung cancers.

The sputum may be cultured in people who are thought to have an infection. This lets bacteria, fungi, or viruses grow in a lab. It may show the exact cause of the infection.

This test can also be done to help diagnose:

  • The presence of asbestos fibers
  • Inflammatory cells

Talk to your doctor about your test results. A test may point to an illness that you do not have. It can also miss an illness that you may have. The doctor will check your symptoms and all test results before making a diagnosis.


Lung cancer. Lab Tests Online—American Association of Clinical Chemistry website. Available at: https://labtestsonline.org/understanding/conditions/lung-cancer/start/3. Updated February 12, 2019. Accessed May 16, 2019

Lung cancer screening. EBSCO DynaMed website. Available at:http://www.dynamed.com/topics/dmp~AN~T901808/Lung-cancer-screening. Updated February 20, 2019. Accessed May 16, 2019.

Non-small cell lung cancer. EBSCO DynaMed website. Available at:http://www.dynamed.com/topics/dmp~AN~T114774/Non-small-cell-lung-cancer. Updated June 15, 2018. Accessed May 16, 2019.

Small cell lung cancer. EBSCO DynaMed website. Available at:http://www.dynamed.com/topics/dmp~AN~T115654. Updated June 15, 2018. Accessed May 16, 2019.

Last reviewed March 2019 by EBSCO Medical Review Board James P. Cornell, MD  Last Updated: 5/16/2019