Medical Advice

Bacterial Vaginosis

What is BV?

Bacterial vaginosis, or BV, is the commonest cause of abnormal vaginal discharge in women from puberty to menopause. Despite being common, it is still not clear what causes BV, and why some women get BV and others don’t.

The hallmark of BV is a thin and sometimes copious vaginal discharge that smells much stronger than usual. Some women describe this as a fishy smell, others say that it just doesn’t smell right. The discharge can irritate the vulval skin so that the whole area feels uncomfortable. BV symptoms can change over the course of the menstrual cycle, so that things might be considerably better by the time a doctor is consulted. This can be frustrating, but is to be expected as BV can improve without treatment.

Whilst the cause of BV is not fully understood, we do know that there is a change in the bacteria that are usually found in the vagina. There are fewer lactobacilli, which usually keep the vagina relatively acidic. Other normal vaginal bacteria (and there are quite a number of them) proliferate, causing an increase in vaginal discharge and characteristic odour.

BV can be a frustrating condition because it tends to recur after successful treatment – and we do not know how to prevent this. Research continues to try to work out if BV can be caught from a partner, just like other sexually transmitted infections. Having multiple or sequential sexual partners and not using condoms are risk factors for BV, but on the other hand, treating male partners does not reduce BV recurrences in their female partners. Women who are not sexually active can get BV. Women who have female partners can also get BV and interestingly, their partners often have BV as well: this is the one time when testing and treatment of partners is often recommended. So there continue to be more questions than answers to the question “ how did I get BV?”.

Diagnosis and treatment

BV can be diagnosed by your doctor if there is a history of malodorous discharge, and examination reveals a thin discharge that is more alkaline than usual, together with the characteristic odour. A swab of the vagina is usually taken and the lab will look for evidence of bacterial overgrowth under the microscope (‘clue cells’ are cells from the vaginal wall with an excess of bacteria stuck to them). The lab will also try to grow any abnormal bacteria on the swab, but as BV seems to be caused by some of the usual vaginal bacteria simply growing in more than usual numbers, this does not help with diagnosis.

Treatment of BV is based on antibiotics, which aim to bring the vaginal bacteria back into a more normal balance. Both oral and topical vaginal treatments are available, but unlike over-the-counter thrush treatments, you will need to see your doctor and get a prescription. Antibiotics work well, with 70-90% cure rates, but unfortunately, up to 50% of women will have another episode of BV within 6 months. Research being conducted in Australia at the moment is trying to establish whether there are more effective ways of treating BV.

As well as the discomfort and inconvenience of BV, there are some more serious potential consequences. BV can cause infection of the uterus and fallopian tubes (pelvic inflammatory disease) especially after invasive procedures like termination of pregnancy. Many centres will test for BV before such procedures – and you can ask for a test if you think you have BV and are going to have gynaecological surgery.

BV has also been linked to an increased risk of acquiring chlamydia, the commonest sexually transmitted infection in young women in Australia, as well as other infections (including HIV, which is especially important in countries with high rates of HIV in the heterosexual population).

If you are pregnant and have BV, treatment is recommended, usually with oral antibiotics. BV in pregnancy has been associated with an increased risk of late miscarriage and pre-term birth (before 37 weeks) and treatment may reduce this risk.

So what can I do if I think I have BV?

See your doctor, explain your symptoms, ask about BV, and ask to be examined.

If you are prescribed treatment, take the whole course, even if you feel better after just a few doses

If you have a male sexual partner, consider using condoms for a while: even though there is no evidence at the moment to suggest that your partner should be treated, using condoms may reduce recurrence.

If you have a female sexual partner and she also has symptoms of BV, encourage her to see her doctor and get treatment at the same time as you

Remember vulval skin care – your skin can be irritated by the increased discharge of BV and may take a while to settle. See Caring for your skin down there.

Becoming more confident about recognising the symptoms of BV means that you can seek help early if you have a recurrence. Treatment is the same as for a single episode. BV recurrences can be very frustrating but fortunately they seem to settle down eventually for most women.