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 an illustration 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. However, 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 medications.
• Have allergies to any medications, 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 this procedure, its risks, how it will be done, or what the results will indicate. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).

Do not eat or drink for at least 8 to 10 hours before the procedure.

Arrange to have someone drive you home after the procedure

How It Is Done

Home or office sample

Three sputum samples are usually collected over 3 days. Your doctor will give you a container to collect the sputum. This container may have a small amount of liquid (called fixative) in it. The fixative helps preserve the sample. Do not drink this liquid.

For best results, collect the sample in the morning right after waking up. Follow these steps:

• If you wear dentures, remove them before collecting the sample.
• Rinse your mouth with water.
• Take about four deep breaths followed by a few short coughs, then inhale deeply and cough forcefully into the container. Sputum is not the same as saliva, so make sure to get a sample of mucus from deep in your airway.

Carefully follow your doctor's instructions about where to deliver the sample. You may be instructed to take the sample to the doctor's office or to a laboratory. Deliver the sample soon after you obtain it. You may be instructed to refrigerate the sample if you are unable to deliver it immediately.

Bronchoscopy sample

See the medical test Bronchoscopy for detailed information on how this procedure is done.