Sputum fungal smear
Definition
A sputum fungal smear is a laboratory test that looks for fungus in a sputum sample. Sputum is the material that comes up from air passages when you cough deeply.
Alternative Names
KOH test; Fungal smear - sputum; Fungal wet prep; Wet prep - fungal
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 lungs into a special container.
The sample is sent to a lab and examined under a microscope.
How to Prepare for the Test
There is no special preparation.
How the Test will Feel
There is no discomfort.
Why the Test is Performed
Your health care provider may order this test if you have symptoms or signs of a lung infection, such as if you have a weakened immune system due to certain medicines or diseases such as
Normal Results
A negative result means no fungus was seen in the test sample.
Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.
What Abnormal Results Mean
Abnormal results may be a sign of a fungal infection. Such infections include:
Aspergillosis Blastomycosis Coccidioidomycosis Cryptococcosis Histoplasmosis
Risks
There are no risks associated with a sputum fungal smear.
References
Banaei N, Deresinski SC, Pinsky BA. Microbiologic diagnosis of lung infection. In: Broaddus VC, Ernst JD, King TE, et al, eds. Murray and Nadel's Textbook of Respiratory Medicine. 7th ed. Philadelphia, PA: Elsevier; 2022:chap 19.
Saullo JL, Alexander BD. Fungal infections: opportunistic. In: Broaddus VC, King TE, Ernst JD, et al, eds. Murray and Nadel's Textbook of Respiratory Medicine. 7th ed. Philadelphia, PA: Elsevier; 2022:chap 57.
Review Date: 12/31/2023
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