Sputum Culture and Cytology Study

Sputum Tests Screen for Lung Infections

Sputum is the substance expelled from your respiratory tract when you cough or clear your throat. It may contain a variety of material, including mucus, cellular debris, blood, pus and bacteria. Your doctor may order a sputum culture or cytology study to screen and diagnose bacterial infections of the lungs such as tuberculosis.

Preparation and Procedure

Before collecting a sputum specimen for the culture or study, contact your nearest lab to obtain a sterile collection container. To collect the specimen:

  • In the morning when you wake up, blow your nose to discharge any nasal and sinus secretions that have accumulated during the night. Discard them.
  • Clean and rinse your mouth, teeth and gums with water. Do not brush with toothpaste.
  • Breathe deeply, inhaling to the full capacity of your lungs, then exhale with a cough.
  • Expectorate sputum from your lungs into the sterile collection container.
  • Do not expectorate saliva from your mouth. Saliva may cause contamination of the specimen, and you may be asked to collect another if it is found to be unsuitable for analysis.
  • Deliver the specimen to the lab immediately. If this is not possible, you may refrigerate the specimen for up to 24 hours before delivering it.

Time Required

Your time at the lab will be limited to the amount of time it takes to sign in, register with admitting and leave your specimen. Results from the culture or study are typically sent to your doctor within a few days; be assured, however, that any critical results are communicated immediately. Your doctor will discuss the results with you once he or she has reviewed them.


Michigan law requires that a valid order signed by an authorized person be presented before any laboratory test or procedure can be conducted. Authorized persons are defined as physicians, physician assistants, or nurse practitioners. These professionals are legally responsible for interpreting the results of tests based on their knowledge of the individual patient.

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