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Vaginal Wet Mount

Test Overview

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).

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 infection (STI).
  • Trichomoniasis. Trichomoniasis is an infection 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 STI.
  • Bacterial vaginosis. Bacterial vaginosis is a change in the balance of bacteria that are normally present in the vagina. The vaginal discharge is thin and milky with a strong fishy odor. Many women have no symptoms. Bacterial vaginosis is not an STI.
  • Other sexually transmitted infections (STIs). Infections such as chlamydia, genital warts, syphilis, herpes simplex, and gonorrhea can also affect the vagina. These infections are found by doing other tests.

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.

How To Prepare

Do not douche, use tampons, or use vaginal medicines for 24 hours before the test.

A vaginal wet mount is not done during your menstrual period. Menstrual blood on the slide can change the results.

If you are or might be pregnant, tell your doctor before the vaginal wet mount is done.

How It Is Done

You will take off your clothes below the waist and drape a gown around your waist. You will then lie on your back on an examination table with your feet raised and supported by stirrups. This allows your doctor to look at the genital area.

Your doctor will put a smooth, curved speculum into your vagina. The speculum gently spreads apart the vaginal walls, which allows your doctor to see the inside of the vagina and the cervix.

Samples of fluid inside the vagina are taken with a swab or spatula. The sample is put on a slide for testing.

How It Feels

You may feel some discomfort when the speculum is inserted, especially if your vagina is irritated and tender. There may be a small amount of bleeding after this test.

Risks

There are no problems from collecting a sample of vaginal secretions.

Results

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). Your doctor may talk to you about the results after the test. If the sample needs to be looked at by a lab, the results may be ready in 1 to 2 days.

Vaginal discharge
Normal:

No abnormal vaginal discharge is present. A small amount of discharge is normal.

Abnormal:

A white, lumpy discharge that looks like cottage cheese may mean a vaginal yeast infection is present. A yellow-green, foamy discharge that has a bad odor may mean trichomoniasis is present. A thin, gray-white vaginal discharge with a strong fishy odor may mean bacterial vaginosis is present.

 

Wet mount
Normal:

No yeast, bacteria, trichomoniasis, or clue cells are found on the slide. White blood cells are not present or very low in number.

Abnormal:

High numbers of white blood cells often mean a vaginal infection. Yeast cells found on the wet mount mean a vaginal yeast infection is present. Trichomonads on the wet mount mean trichomoniasis is present. Clue cells means bacterial vaginosis is present. If many Gardnerella vaginalis bacteria are present, this also may mean bacterial vaginosis is present.

 

KOH slide
Normal:

No yeast is found.

Abnormal:

Yeast cells means a yeast infection is present.

 

Vaginal pH1
Normal:

Vaginal pH is 3.8–4.5.

Abnormal:

Vaginal pH is higher than 4.5.

 

Whiff test
Normal:

Adding potassium hydroxide (KOH) solution to vaginal discharge does not cause a fishy odor.

Abnormal:

A fishy odor made by the whiff test means bacterial vaginosis is present.

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

  • Having your period.
  • Using a vaginal medicine, such as a nonprescription vaginal yeast medicine, 2 to 3 days before this test.
  • Having sex within 24 hours before the test, which can affect the vaginal pH.

What To Think About

  • Some causes of vaginitis are not found by a vaginal wet mount, including atrophic vaginitis and some STIs, such as herpes simplex. Atrophic vaginitis can be found on a vaginal smear when dye is added to the vaginal discharge on the slide. The slide is looked at under a microscope for cell changes that show atrophic vaginitis.
  • Sometimes a sample of the vaginal discharge is put in a special cup to see if bacteria, yeast, or trichomonads will grow. This is called a vaginal culture.
  • The sex partners of women with trichomoniasis are generally treated for the infection so they do not reinfect their partners after treatment. Some doctors recommend treating the sex partners of women with bacterial vaginosis, but most do not. Partners of women who have vaginal yeast infections are not generally treated for yeast infections. To learn more, see the topic Tests for Bacterial Vaginosis.
  • Infections such as chlamydia, genital warts, syphilis, herpes simplex, and gonorrhea can also affect the vagina.
  • A vaginal yeast infection can occur after a woman is treated with antibiotics or in a woman whose diabetes is poorly controlled. Recurring yeast infections may be seen when a woman's immune system is weakened. The immune system can be weakened by old age, infections such as AIDS, or treatment for cancer.

References

Citations

  1. Epstein A, Subir R (2010). Vulvovaginitis. In Management of Common Problems in Obstetrics and Gynecology, 5th ed., pp. 225–230. Chichester, UK: Wiley-Blackwell.

Other Works Consulted

  • Eckert LO, Lentz GM (2007). Infections of the lower genital tract. In VL Katz et al., eds., Comprehensive Gynecology, 5th ed., pp. 569–606. Philadelphia: Mosby Elsevier.
  • Epstein A, Subir R (2010). Vulvovaginitis. In Management of Common Problems in Obstetrics and Gynecology, 5th ed., pp. 225–230. Chichester, UK: Wiley-Blackwell.
  • Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.

Credits

By Healthwise Staff
Primary Medical Reviewer Sarah Marshall, MD - Family Medicine
Specialist Medical Reviewer Deborah A. Penava, BA, MD, FRCSC, MPH - Obstetrics and Gynecology
Current as of March 12, 2014

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