Procedure and Preparation For Conducting a KOH Test

Submitted on March 27, 2012

A KOH test uses a potassium hydroxide or KOH preparation to check for fungal infections on the skin. A sample of the infected skin is scraped out lightly and placed on a slide that has KOH solution. The slide is subsequently heated so that the skin cells are dissolved by the solution, but the fungus cells prevail. These cells can be examined with a microscope and sometimes with the helps of color stains that make the fungus more visible.

Reason for KOH Test

A KOH test for fungus is done if you have itchy and red skin; scaly blisters and bumps; or, any other skin-related fungal infection.

Sometimes, the doctor might be able to determine if you have a skin infection or not, by just looking at the fungal infection and the KOH test for fungus may not be necessary. If a fungal infection is detected through a KOH test, then you may need to do other tests to find out the cause of the skin problem.

Vaginal Wet Mount

Fungus in the vagina is often detected through a vaginal wet mount. Fungus in the vagina might cause inflammation of the vagina, or vaginitis. The latter is generally caused by a reaction to vaginal cosmetic products like douche, oils, soaps, or jellies. Unusual discharge, pain while urinating, and itching are some of the symptoms of vaginits.

Testing For Vaginal Fungus

There are various ways that a vaginal sample can be tested -

Wet mount

In this, the sample of discharge is placed on a slide and is mixed with a saline solution. The technician observes the slide under a microscope for traces of yeast cells, bacteria, clue cells, infected white blood cells, and trichomoniasis (trichomonads).

KOH slide

The KOH test might be done on the sample of vaginal discharge to check for yeast infection.

Vaginal pH

If a woman has atrophic vaginitis, trichomoniasis, and bacterial vaginosis, then the pH level in the vagina is more than 4.5.

Whiff test

Drops of KOH or potassium hydroxide are added to vaginal discharge. A fishy odour means that there is bacterial vaginosis.


Before these tests, you are advised not to use vaginal medicines, tampons, and douche for 24 hours.


You will be requested to put on a hospital gown and take off your underwear. You will then be made to lie on the examination table with your feet in the stirrups. The doctor will examine your vagina and cervix with a curved speculum. A spatula or a swab is used to take out samples of vaginal fluid, and this sample is placed on a slide for testing.

How will you feel

You might feel uncomfortable, tender and irritated during and after the test. There might be a bit of bleeding too.