A vaginal wet mount (sometimes called a vaginal smear) is a test to find the cause of vaginitis, or inflammation of the vagina and the area around the vagina (vulva). See an illustration of female genitalia.

Vaginitis is often caused by an infection, but it may also be caused by a reaction to vaginal products such as soap, bath oils, spermicidal jelly, or douches. Vaginitis may cause symptoms such as vaginal itching, pain, or discharge.

Infections that can cause vaginitis are common and include:

• Yeast infection. A vaginal yeast infection is caused by a type of yeast called Candida albicans. A yeast infection is also called a candida infection, or candidiasis. A vaginal yeast infection often causes itching and a white, lumpy discharge that looks like cottage cheese. It also causes pain with sexual intercourse. A yeast infection is not a sexually transmitted disease (STD).
• Trichomoniasis. Trichomoniasis is a disease caused by a parasite (Trichomonas vaginalis). It is sometimes called trichomonas infection, trichomonal infection, or simply trich (say "trick"). Trichomoniasis causes a vaginal discharge that is yellow-green, foamy, and bad-smelling. Pain with sex or urination may be present. Lower belly pain may also be present. Trichomoniasis is spread by sexual contact and is an STD.
• Bacterial vaginosis. Bacterial vaginosis is a change in the balance of bacteria that are normally present in the vagina. The vaginal discharge is thick and milky with a strong fishy odor. Many women have no symptoms. Bacterial vaginosis is not an STD.
• Other sexually transmitted diseases (STDs). Infections such as chlamydia, genital warts, syphilis, herpes simplex, and gonorrhea can also affect the vagina. These diseases are found by doing other tests. Genital warts may cause abnormal Pap test results.

To find bacterial vaginosis, a vaginal sample may be tested by:

• Wet mount. A sample of the vaginal discharge is placed on a glass slide and mixed with a salt solution. The slide is looked at under a microscope for bacteria, yeast cells, trichomoniasis (trichomonads), white blood cells that show an infection, or clue cells that show bacterial vaginosis.
• KOH slide. A sample of the vaginal discharge is placed on a slide and mixed with a solution of potassium hydroxide (KOH). The KOH kills bacteria and cells from the vagina, leaving only yeast for a yeast infection.
• Vaginal pH. The normal vaginal pH is 3.8 to 4.5. Bacterial vaginosis, trichomoniasis, and atrophic vaginitis often cause a vaginal pH higher than 4.5.
• Whiff test. Several drops of a potassium hydroxide (KOH) solution are added to a sample of the vaginal discharge. A strong fishy odor from the mix means bacterial vaginosis is present.

Why It Is Done

A vaginal wet mount is done to find the cause of vaginal itching, burning, rash, odor, or discharge.