See your GP or visit a sexual health or genitourinary medicine (GUM) clinic as soon as possible if you have any abnormal discharge from your vagina.

It's important to determine whether you have bacterial vaginosis (BV) or a similar condition, such as trichomoniasis or gonorrhoea. These can both also cause abnormal vaginal discharge.

Tests for BV are sometimes offered to women during pregnancy or before certain procedures.


Your GP or healthcare professional may diagnose BV from a description of your symptoms and by examining your vagina. In particular, they'll look for:

  • a thin, greyish discharge
  • an unpleasant smell

In some cases, this may be enough to confirm your diagnosis. However, you may need further tests if you're sexually active and may have a sexually transmitted infection (STI) instead.


A sample of cells may be taken from the wall of your vagina using a plastic loop or swab. A swab looks a bit like a cotton bud, but is smaller, soft and rounded.

The swab or loop picks up samples of discharge and cells. It only takes a few seconds and isn't usually painful, although it may be slightly uncomfortable for a moment.

The samples are examined to check for signs of BV. In some centres, the result may be available immediately, but it can take up to a week to get the results if the sample is sent to a laboratory.

The level of acidity (pH) of your vagina may also be measured. A swab will be taken from inside your vagina and wiped over a piece of specially treated paper. The paper changes colour depending on the pH level. A pH level higher than 4.5 is an indication that you may have BV.

Page last reviewed: 12/10/2015
Next review due: 01/10/2018