BV (bacterial vaginosis) is usually diagnosed on the basis of typical symptoms (fishy-smelling grey or greenish discharge), and is confirmed by taking a vaginal swab, which can be performed by a doctor or nurse. Tests for STIs such as chlamydia and gonorrhoea may also be advised at the same time, to rule out any other causes of vaginal discharge. This is particularly important if you have a recent new sexual partner. 

If you are pregnant, and suspect you may have BV, it’s important to get tested and treated, as it can increase the risk of pregnancy-related complications.

BV often returns after a few weeks or months- in these cases, if the symptoms are the same as before, it may be possible to treat immediately without needing another swab test. However if the symptoms are different in any way, it is safer to get retested.