Bacterial Vaginosis Test
Reviewed
Also called: BV test, vaginal pH test, KOH test, wet mount test, vaginal smear
This test checks a sample of vaginal discharge for signs of bacterial vaginosis (BV), an infection caused by an imbalance of bacteria in the vagina. It can be done using a microscope (vaginal smear/wet mount), a whiff test for odor, a vaginal pH test, or a PCR test. Untreated BV can increase the risk of STDs and preterm birth. At-home pH kits are available but cannot diagnose BV.
Specimen: vaginal discharge
Why this test may be ordered
- You have symptoms of BV, such as unusual gray or white discharge, a strong fish-like odor (especially after sex), vaginal pain/itching, or burning when urinating.
- You have a female sex partner who has BV or symptoms that could be BV.
Preparation and collection
For 24 hours before your test, you'll usually need to avoid: using tampons, douching, using creams or medicines in the vagina, and having vaginal sex.
vaginal swab
With a BV test from your provider, you may feel some mild discomfort when the speculum is put in your vagina.
Understanding results
Your provider will interpret your results based on the specific tests performed. Below are common patterns.
- Vaginal pH over 4.5: You are more likely to have BV. Limitation: A pH test alone cannot diagnose BV. Next step: Your provider will likely use this result along with other tests to make a diagnosis.
- Vaginal pH 4.5 or lower: You are less likely to have BV, but it is not ruled out. Limitation: A pH test alone cannot diagnose BV. Next step: Your provider may do more tests to find the cause of your symptoms.
- Abnormal (positive) on vaginal smear or whiff test: You have a bacterial infection (BV). Limitation: This result is based on microscopic examination or whiff test. Next step: Your provider will probably prescribe antibiotics.
- Normal (negative) on vaginal smear or whiff test: You do not have BV. Limitation: This result is based on microscopic examination or whiff test. Next step: Your provider may do more tests to find the cause of your symptoms.
- You may feel mild discomfort when the speculum is inserted during sample collection.
- At-home pH test kits cannot diagnose BV; a high pH only suggests a higher likelihood, and a normal pH does not rule out BV.
- PCR testing is more expensive and not used as often as other methods.
What to do next
If your results show you have a BV infection, your provider will probably prescribe antibiotic pills and/or antibiotic creams or gels that you put in your vagina. If your results show you don't have BV, your provider may do more tests to find the cause of your symptoms. If you have questions about your results, talk with your health care provider.
- What do my test results mean for my health?
- Do I need any follow-up tests?
- Should my female sex partner also be tested?