Bacterial vaginosis

Bacterial vaginosis is the most common reason for a change in vaginal discharge in women of reproductive age. It is not an infection brought in from outside: what changes is the balance of the vagina's own bacteria. Lactobacilli become scarce and their place is taken by microbes that live without oxygen. About half of women feel nothing at all, and the condition turns up by chance, on a swab taken before a procedure or at a routine check.

What changes inside

A healthy vagina rests on an acid environment: lactobacilli produce acid, and other bacteria have a hard time in it. In bacterial vaginosis there are almost no lactobacilli left, the acidity shifts towards neutral, and a dense film of anaerobic bacteria spreads over the vaginal wall, made up of gardnerella and its neighbours. That film explains the main peculiarity of the condition: an antibiotic kills the bacteria floating free, while the community glued to the lining survives the course and grows back.

How it shows itself

Usually the smell changes first, not the way you feel.

• discharge becomes thin, uniform and greyish white, coating the vaginal wall evenly;
• a strong smell appears, most often described as fishy; it gets worse after sex and during a period, because an alkaline environment releases the odorous substances;
• there is often more discharge than usual, though the amount may stay the same;
• as a rule there is no itching, burning, soreness or redness.

Why it is mistaken for thrush

Both change the discharge, but they are treated with different medicines, and getting it wrong costs weeks.

• Bacterial vaginosis: thin grey discharge, strong smell, no itching.
• Thrush: thick white discharge in curds, intense itching, redness and burning, little smell.
• Trichomoniasis: heavy yellow green frothy discharge, burning, discomfort when passing urine; this one is a sexually transmitted infection and the partner needs treatment too.
• After the menopause the leading complaint is dryness and thinning of the lining rather than smell.

Chlamydia and gonorrhoea often give no clear signs and sit quietly alongside vaginosis. So when discharge changes for the first time, testing makes far more sense than picking a pessary from an internet description.

What actually matters

Vaginosis is not the result of poor hygiene; if anything it is more common in women who wash especially thoroughly and rinse inside.

• douching and internal washing with water, herbs or antiseptics, which flushes lactobacilli out;
• perfumed soaps, gels, intimate deodorants and wipes;
• a new partner, several partners, sex without a condom;
• a female partner: in couples of two women both often have it;
• an intrauterine device, especially in the first months after it is fitted;
• smoking;
• a recent course of antibiotics taken for something else.

It also occurs in women who have never had sex, and sometimes no cause can be found at all. Vaginosis is not passed on the way a sexually transmitted infection is, yet its link with sex is real: intercourse can upset the balance, which is not the same as catching something from a partner.

What it risks if left alone

In itself vaginosis is not a serious illness, and some episodes settle without medication. The problem is that the acid environment is part of the body's defence, and without it the lining copes far worse.

• a higher chance of picking up chlamydia, gonorrhoea, trichomoniasis, genital herpes and HIV;
• a higher risk of inflammation of the womb and tubes after an intrauterine device is fitted, after a termination, a surgical womb procedure or a hysteroscopy, which is why it is treated before such procedures even when it causes no trouble;
• in pregnancy it is linked with premature birth, late miscarriage, early rupture of the membranes and inflammation of those membranes.

Most pregnancies with vaginosis run their normal course, but discharge that changes during pregnancy is a reason to tell the doctor or midwife straight away.

When to seek help without waiting

• pain low in the abdomen or deep pain during sex, fever, chills: vaginosis does not behave like this, these are signs of inflammation of the womb and tubes;
• bleeding between periods or after sex;
• discharge mixed with pus or blood, ulcers, blisters or sores on the lining;
• any change in discharge during pregnancy;
• symptoms that started after unprotected sex with a new partner;
• episodes that come back more than three times a year.

How the diagnosis is made

The diagnosis is built from several findings, not from one line on a form. At the appointment the discharge is assessed, the acidity is measured with a strip and a swab is taken from the vaginal wall. Under the microscope the clinician looks for cells of the lining coated with bacteria and checks how many lactobacilli remain. Sometimes a drop of alkali is added, which brings out the characteristic smell.

A culture for gardnerella on its own is of little use: it is also found in healthy women with no complaints, so the finding alone is not a diagnosis. Molecular panels that count bacteria help in doubtful cases, but they are read together with the examination, not instead of it. Chlamydia and gonorrhoea are checked at the same time.

How it is treated

Antibiotics that work against anaerobic bacteria do the job: nitroimidazole derivatives and clindamycin. The form varies, tablets by mouth or a gel, cream or pessary used vaginally; results are comparable, so the choice is mostly about tolerance and convenience. The regimen and its length are decided by the doctor.

• while taking nitroimidazoles by mouth, and for a few days afterwards, alcohol is avoided: a severe reaction with nausea, palpitations and a drop in blood pressure is possible;
• clindamycin cream damages latex, so a condom or diaphragm is unreliable on those days;
• the course is finished in full, even if the smell disappears on the second day;
• vaginosis without symptoms is not always treated: it is usually treated in pregnancy and before gynaecological procedures.

For a long time treating a regular male partner was considered pointless. There is now evidence that when vaginosis keeps coming back, treating the partner at the same time reduces the number of recurrences; that decision belongs to the doctor. For a female partner, testing is discussed separately.

When it keeps coming back

Recurrence is closer to the rule than the exception: within a year vaginosis returns in more than half of the women treated. This is not a sign of wrong treatment, nor a question of cleanliness; the explanation lies in that film on the lining and in how slowly lactobacilli recover.

With frequent episodes the doctor repeats the course and then prescribes spaced maintenance applications of gel for a few months, reconsiders the intrauterine device if everything began after it was fitted, and works out with the patient what the flare-ups coincide with: the cycle, sex, internal washing. Products containing lactobacilli and preparations that acidify the vagina are discussed as an addition: there is no convincing proof that they prevent recurrence, and they do not replace the antibiotic.

Everyday care

• wash the outside only, with warm water or a mild unscented product;
• no douching and nothing inserted for cleaning;
• put aside perfumed gels, bubble baths, deodorants and wipes;
• a shower rather than long baths with additives and antiseptics;
• cotton underwear washed with unscented detergent;
• a condom with a new partner, which also protects against infections;
• stopping smoking.

Online consultation

In an online consultation the doctor will go through what the discharge looks like and when it changed, help tell vaginosis apart from thrush and from infections that need different medicines, say which tests are worth doing and whether an examination is needed, and, if episodes keep returning, put together a plan for the months ahead.

This material is for information only and does not replace medical advice.