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Bacterial Vaginosis Tests

Test Overview

Tests for bacterial vaginosis take samples of fluid from the vagina. The samples are looked at under a microscope to see if they show signs of infection.

Bacterial vaginosis is caused by a change in the balance of bacteria in the vagina. Normally, there are a lot of "good" bacteria and some "bad" bacteria in the vagina. The good types help control the growth of the bad types. But when you have bacterial vaginosis, there are not enough good bacteria and too many bad bacteria.

Many women with bacterial vaginosis don't have symptoms. The most common symptom is an increase in vaginal discharge. The discharge often has a fishy smell.

Women who have bacterial vaginosis with symptoms during pregnancy need to be treated. Some pregnant women who don't have symptoms should also be treated.

Tests

Tests for bacterial vaginosis include:

  • Wet mount. A sample of vaginal discharge is checked for bacteria, white blood cells, and unusual cells called clue cells. If clue cells are found, it means you may have bacterial vaginosis.
  • Whiff test. A sample of discharge is checked to see if a strong fishy odor is created when a special solution is added. A fishy odor usually means you have bacterial vaginosis.
  • Vaginal pH. The pH of a sample of vaginal discharge is measured. Bacterial vaginosis often causes a pH that is higher than normal.
  • Molecule test. A sample of vaginal discharge is tested for the genetic material, or DNA, of this bacteria.

Why It Is Done

Tests for bacterial vaginosis are done to help find the cause of symptoms such as abnormal vaginal discharge, irritation, or pain.

How To Prepare

Your doctor may ask you not to douche, have sex, or use vaginal medicines for 24 hours before this test.

How It Is Done

You will take off your clothes below the waist. You'll have a gown to drape around your waist. You will then lie on your back on an examination table. Your feet will be raised and supported by stirrups. This is similar to having a pelvic examination or Pap test.

Your doctor will insert a lubricated tool called a speculum into your vagina. The speculum gently spreads apart the vaginal walls. This allows your doctor to see the inside of the vagina and the cervix.

Samples of fluid inside the vagina are then collected with a swab.

How It Feels

You may feel some discomfort when the speculum is put in, especially if your vagina is irritated and tender.

Risks

There is little chance of having a problem from a bacterial vaginosis test.

Results

Tests for bacterial vaginosis

Normal

There is no abnormal discharge in the vagina.

A wet mount does not show clue cells or large numbers of bacteria that cause bacterial vaginosis.

Adding a special solution to a sample of the discharge doesn't cause a fishy odor.

Vaginal pH is in the normal range.

Abnormal

There is a thin, grayish white discharge in the vagina.

A wet mount shows clue cells or large numbers of the types of bacteria that cause bacterial vaginosis, or both.

Adding a special solution to a sample of the discharge causes a fishy odor.

Vaginal pH is higher than normal.

Credits

Current as of: July 17, 2020

Author: Healthwise Staff
Medical Review:
Sarah Marshall MD - Family Medicine
Martin J. Gabica MD - Family Medicine
Kathleen Romito MD - Family Medicine
Devika Singh MD, MPH - Infectious Disease