Bacterial vaginosis (BV) has two hallmark signs: a thin, grayish discharge and a noticeable fishy odor, especially after sex. But about half of people with BV have no symptoms at all, which makes it one of the trickier vaginal infections to identify on your own. Here’s what to look for, how it differs from a yeast infection, and what happens when you go in for testing.
The Main Signs of BV
The most recognizable symptom is a change in vaginal discharge. With BV, discharge tends to be thin and watery, with a milklike consistency that coats the vaginal walls. The color is typically off-white, gray, or slightly greenish, and the volume is often heavier than usual.
The other telltale sign is smell. BV produces a fishy odor that many people notice most strongly after intercourse. The odor can also become more noticeable around menstruation. Some people describe it as faint, while others find it strong enough to detect through clothing.
BV can cause mild irritation, but it typically does not cause pain. If you’re experiencing significant itching, burning, or soreness, something else may be going on, either alongside BV or instead of it.
BV vs. Yeast Infection
These two conditions are easy to confuse because both involve abnormal discharge, but the discharge looks and feels quite different. BV discharge is thin, grayish, and tends to have that fishy smell. Yeast infection discharge is thick and white, often described as resembling cottage cheese, and it usually has little to no odor.
The other major difference is pain and itching. Yeast infections commonly cause itching, burning, and pain during sex. BV rarely causes any of those. If your main complaint is itching with thick white discharge, a yeast infection is more likely. If your main complaint is odor with thin gray discharge, BV is more likely.
Can You Be Asymptomatic?
Yes, and it’s common. At least 50% of people whose lab results show BV have no noticeable symptoms. This matters because untreated BV, even without symptoms, can increase susceptibility to sexually transmitted infections like chlamydia, gonorrhea, and HIV. During pregnancy, BV raises the risk of premature birth and low birth weight (under 5.5 pounds). BV sometimes resolves on its own, but treatment reduces these risks significantly.
What an At-Home pH Test Can Tell You
Over-the-counter vaginal pH test strips are available at most pharmacies and can give you a useful clue. Normal vaginal pH falls between 3.8 and 4.5, which is mildly acidic. BV shifts pH upward, typically into the 5.0 to 6.5 range. If your pH reads above 4.5, BV is a strong possibility.
There are important limitations, though. A high pH result doesn’t confirm BV on its own because other infections and even hormonal changes (like menopause) can also raise vaginal pH. And a normal pH result doesn’t rule out every type of infection. Yeast infections, for example, often don’t change pH at all, so you could have a normal reading and still have something going on. A pH strip is a reasonable first step, but it’s not a substitute for a clinical exam.
How Providers Diagnose BV
In a clinical setting, diagnosis usually relies on a combination of physical signs rather than any single test. Providers look for at least three of the following four findings:
- Thin, homogeneous discharge with a milklike consistency coating the vaginal walls
- Vaginal pH above 4.5
- Fishy odor detected during examination, sometimes after applying a chemical solution to a discharge sample
- Clue cells visible under a microscope, which are normal vaginal cells that appear studded with bacteria clinging to their surface
The clue cell finding is considered the most significant of the four. When an experienced examiner looks for them under a microscope, the test correctly identifies BV about 98% of the time when it’s positive.
Some labs use a more detailed approach called a Nugent score, which grades vaginal bacteria on a 0 to 10 scale based on a stained sample. A score of 0 to 3 reflects healthy bacterial balance, 4 to 6 is considered intermediate, and 7 to 10 confirms BV. This method is considered the gold standard in research settings, though many clinics use the faster bedside criteria instead.
What to Pay Attention To
If you’re trying to figure out whether you have BV, focus on two things: what your discharge looks like and whether there’s a fishy smell. Those two signs together are the strongest indicators you can identify at home. A pH strip can add another data point. But keep in mind that BV overlaps with other conditions, and the only way to confirm it is through a clinical exam. This is especially worth doing if you’re pregnant, if symptoms keep coming back, or if over-the-counter yeast infection treatments haven’t helped, since that’s often a sign the problem was BV all along.