Sputum cytology examines a sample of sputum (mucus) under a microscope to determine whether abnormal cells are present. Sputum is not the same as saliva. Sputum is produced in the lungs and in the airways leading to the lungs. Sputum has some normal lung cells in it. See a picture of the lungs' airways.

Sputum cytology may be done to help detect certain noncancerous lung conditions. It may also be done when lung cancer is suspected.

A sputum sample may be collected:

• By a person coughing up mucus.
• By breathing in a saltwater (saline) mist and then coughing.
• During bronchoscopy, which uses a bronchoscope to look at the throat and airway.

Why It Is Done

Sputum cytology is done to detect:

• Lung cancer. But this is not used as a screening test for people at risk for developing lung cancer, such as smokers.
• Noncancerous lung conditions, such as pneumonia or inflammatory diseases, tuberculosis, or the buildup of asbestos fibers in the lungs (asbestosis).

How To Prepare

Home or office sample

No special preparation is required if the sputum sample is to be collected at home or in your doctor's office.

Bronchoscopy sample

Before you have a bronchoscopy to collect a sputum sample, tell your doctor if you:

• Are taking any medicines.
• Have allergies to any medicines, including anesthetics.
• Have any bleeding problems or take blood thinners, such as aspirin or warfarin (Coumadin).
• Are or might be pregnant.

For a bronchoscopy, you will also be asked to sign a consent form. Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?) .

Your doctor will tell you how soon before the procedure to stop eating and drinking. In most cases, you will need to stop eating at least 6 hours before your procedure. You may be able to drink clear liquids, such as water, coffee, or tea, up to 2 hours before the procedure. But be sure to follow the exact instructions your doctor gives you.

Arrange to have someone drive you home after the procedure.