Bacterial vaginosis (BV), also known as vaginal bacteriosis is the most common cause of vaginal infection for women of childbearing age. Although it frequently develops after sexual intercourse with a new partner, bacterial vaginosis is not considered as an STI (sexually transmitted infection). BV is more common in women with multiple partners.
Bacterial vaginosis - not to be confused with candidiasis (yeast infection) or Trichomonas vaginalis (trichomoniasis) which are not caused by bacteria - is caused by an imbalance of naturally occurring bacterial flora (the usual bacteria found in a woman's vagina). Smoking and the use of some hygiene products are linked to a higher risk of developing BV.
According to the National Health Service (NHS), UK, approximately 12% to 30% of adult women in the UK may be affected; about 20% of pregnant women in the UK are affected. The Centers for Disease Control and Prevention (CDC), USA, estimates that about 16% of US women are affected.
Bacterial vaginosis can sometimes be asymptomatic - about 50% of women with BV have no symptoms at all. Doctors say treatment is not required if the woman is found to have BV, but has no symptoms. Sometimes BV can appear and disappear for no reason.
Even though antibiotic medication is effective in up to 90% of cases, 25% of women will develop BV again within four weeks.
A pregnant woman with BV has a slightly higher risk of complications, such as giving birth before the 37th week of pregnancy.
Symptoms of bacterial vaginosis
A symptom is something the patient senses and describes, while a sign is something other people, such as the doctor notice. For example, drowsiness may be a symptom while dilated pupils may be a sign.
Approximately 50% of all women with BV have no symptoms (asymptomatic). If a woman does have symptoms, she does not need to get tested to find out.
The main sign is in the vaginal discharge:
- Vaginal discharge may become watery and thin
- Vaginal discharge may become grey or white
- Vaginal discharge may have a strong and unpleasant smell, often described as fishy
The following symptoms of bacterial vaginosis are possible, but much less common:
- Burning sensation during urination
- Itching around the outside of the vagina
Causes of bacterial vaginosis
We know that bacterial vaginosis is linked to an imbalance in the bacteria that are normally found in a female's vagina - an imbalance in the vagina's naturally occurring bacterial flora. However, nobody fully understands why this imbalance occurs. The vagina usually contains mostly good bacteria and few harmful bacteria - bacterial vaginosis occurs when these harmful bacteria grow in numbers. We do not know what role these harmful bacteria play in causing BV.
A female's vagina should contain lactic acid bacteria, called lactobacilli. These bacteria produce lactic acid, making the vagina slightly acidic, preventing other bacteria from growing there. If the vagina is not as acidic as it should be, other bacteria may have the opportunity to grow. If there are fewer lactobacilli the vagina may become less acidic.
Any female can develop BV. Some behaviors or activities may upset the balance of the naturally occurring bacterial flora and increase the risk of developing BV, including:
- Douching - using water or a medicated solution to clean the vagina
- Having a bath with antiseptic liquids
- Having a new sex partner
- Having multiple sex partners
- Perfumed bubble baths and some scented soaps
- Using an IUD (intrauterine device), such as a contraceptive device made from plastic and copper that fits inside the uterus
- Using vaginal deodorants
- Washing underwear with strong detergents
- Women who have never had sexual intercourse may be affected
- You cannot get BV from toilet seats, bedding, swimming pools, or touching objects
Diagnosing bacterial vaginosis
The National Health Service (NHS), UK, says that a woman who has any abnormal vaginal discharge should see her GP (general practitioner, primary care physician) as soon as possible so that BV can be diagnosed and other infections, such as gonorrhea or trichomonas vaginalis ruled out. In many countries the woman could visit a sexual health clinic for diagnosis (or genitor-urinary medicine clinic), instead of her GP.
The doctor may be able to diagnose BV from a description of symptoms and carrying out a physical examination, during which he/she will look out for an unpleasant smell and a thin, white/gray discharge. If the patient is sexually active and there is a chance she may have an STI (sexually transmitted infection), the doctor may order some diagnostic tests.
Swab (sample) - the doctor uses a swab or small plastic loop to collect sample cells from the vaginal wall. The alkaline/acid balance (pH) of the vagina may also be measured.
On the next page we look at the treatments for bacterial vaginosis and possible complications associated with the infection.