What is a vaginal wet mount?

Wet Mount

TL;DR

A vaginal wet mount, or wet prep, is a diagnostic test performed by doctors to examine vaginal fluids under a microscope. This test can identify the presence of bacteria, yeast, or other cells, helping to determine the cause of symptoms such as infections. The process involves taking a sample from the vagina or cervix, which is then examined for signs of normal flora or symptoms of infection like yeast infections, trichomoniasis, and bacterial vaginosis. Understanding what a wet mount can reveal about your vaginal health is crucial for accurate diagnosis and treatment.

A wet mount or wet prep (same thing, different name) may be performed in your doctor’s office to examine your vaginal fluids for the presence of certain bacteria or cells, to determine the cause of symptoms.​1​

A doctor can look at saliva, blood, semen, urine or vaginal secretions under the microscope using a wet mount (wet prep). A wet mount or wet prep is used to determine the presence of semen as part of a rape investigation.

A wet mount is not usually performed during your period, since the blood would obscure the results. A wet mount or wet prep relies on your doctor’s eyesight.

You should also not have sex, douche or use any vaginal products or treatments for as long as possible (at least 24 hours, but 72 is better)

The wet mount or wet prep process

First the sample is taken from your vagina or cervix. Where the sample is taken from matters, since some microbes or cells are usually only found in certain areas.

A high vaginal swab is usually the best, as opposed to just around the vaginal entrance, but this will depend on what is wrong. If you have a vulvar condition, taking a sample from closer to the vaginal entrance may be appropriate.

No matter what, you’ll need to have a speculum inserted to push the vaginal walls open so a vaginal fluid sample can be taken. A drop of water or salt solution is used to suspend the vaginal fluid between the slide and what’s known as a cover slip.

The sample is placed onto the glass slide, then a drop of water is placed on top of the specimen. Air bubbles must be kept out of the specimen since they will interrupt viewing via the microscope.

What a wet mount or wet prep can reveal about your vagina

Normal vaginal flora under wet mount or wet prep​2​

  • No yeast or trichomonas found
  • White blood cells and clue cells are absent or low in number

Symptoms of infection found under wet mount or wet prep​3​

  • Yeast infections may appear as lumpy, thick, white discharge, plus yeast buds will be seen, though they are only visible half the time
  • Trichomoniasis causes foul-smelling discharge, yellow or green foamy discharge, with mobile trichomonads visible on slide
  • Bacterial vaginosis appears as a thin, watery, grey, milky discharge with a fishy smell, with diagnosis made if there are over 20 per cent clue cells, plus other signs including a conclusive pH test and whiff test as part of Amsel’s criteria
  • White blood cells are a general sign of infection

Other tests that the sample may be used for in diagnostics

  • pH test – normal vaginal fluids have a pH of between 3.8 and 4.5, with BV, trich and atrophic vaginitis causing a pH greater than 4.5
  • Whiff test, whereby potassium hydroxide (KOH) is added to a sample, then the doctor sniffs the sample to see if it is fishy

When you go to the doctor, ask what they can see! Now you know what they are looking for.

References

  1. 1.
    Vieira-Baptista P, Grincevičienė Š, Oliveira C, Fonseca-Moutinho J, Cherey F, Stockdale CK. The International Society for the Study of Vulvovaginal Disease Vaginal Wet Mount Microscopy Guidelines: How to Perform, Applications, and Interpretation. J Low Genit Tract Dis. Published online February 25, 2021:172-180. doi:10.1097/lgt.0000000000000595
  2. 2.
    Donders GGG. Wet mount microscopy reflects functional vaginal lactobacillary flora better than Gram stain. Journal of Clinical Pathology. Published online April 1, 2000:308-313. doi:10.1136/jcp.53.4.308
  3. 3.
    Frobenius W, Bogdan C. Diagnostic Value of Vaginal Discharge, Wet Mount and Vaginal pH – An Update on the Basics of Gynecologic Infectiology. Geburtshilfe Frauenheilkd. Published online May 19, 2015:355-366. doi:10.1055/s-0035-1545909


Jessica Lloyd - Vulvovaginal Specialist Naturopathic Practitioner, BHSc(N)

Jessica is a degree-qualified naturopath (BHSc) specialising in vulvovaginal health and disease, based in Melbourne, Australia.

Jessica is the owner and lead naturopath of My Vagina, and is a member of the:

  • International Society for the Study of Vulvovaginal Disease (ISSVD)
  • International Society for the Study of Women's Sexual Health (ISSWSH)
  • National Vulvodynia Association (NVA) Australia
  • New Zealand Vulvovaginal Society (ANZVS)
  • Australian Traditional Medicine Society (ATMS)
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