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Sputum fungal smear

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.

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, especially if you have a weakened immune system due to certain medicines or diseases such as cancer or HIV/AIDS.

Normal Results

A normal (negative) result means no fungus was seen in the test sample.

Some labs use different measurements or test different samples. Talk to your doctor 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:


There are no risks associated with a sputum fungal smear.

Alternative Names

KOH test; Fungal smear - sputum; Fungal wet prep; Wet prep - fungal



Chernecky CC, Berger BJ. Sputum, fungus - culture. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. Philadelphia, PA: Elsevier Saunders; 2013:1038-9.

Horan-Saullo JL, Alexander BD. Opportunistic mycoses. In: Broaddus VC, Mason RJ, Ernst JD, et al, eds. Murray and Nadel's Textbook of Respiratory Medicine. 6th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 38.

Review Date 12/10/2015

Updated by: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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