2.5.6 Bacterial Vaginosis

Grading & Level of Importance: B


W. Burgdorf, Munich; R. Woolf, J. McGrath, London;
Revised by A. Salava, E. Hiltunen-Back, A. Ranki, Helsinki




Nonspecific vaginitis, Gardnerella vaginitis, Bacterial vaginitis.


A very common cause of vaginal symptoms in women of reproductive age; lifelong prevalence in Europe 15-20 %.


A disturbance of the normal bacterial flora of the vulva and/or vagina causing a malodorous discharge.

Aetiology & Pathogenesis

Pathogenesis not completely understood; disturbances of normal vaginal microbiota (Lactobacillus spp.) suspected. Detectable overgrowth of anaerobic bacteria with an elevation of the vaginal pH. Predisposing factors: recent use of broad-spectrum antibiotics, use of an intrauterine device, high number of sexual partners.

Signs & Symptoms

Main symptom is a malodorous, milky or grey-white homogeneous vaginal discharge. The discharge can cause irritation of the vulvar skin. The odour of the discharge has a fishy smell and is a common complaint.


Usually localized to vulvar skin and vaginal mucosa.


Not applicable.

Laboratory & other workups

Microscopy of a vaginal smear shows epithelial cells with many adherent cocci (clue-cells) with almost no leucocytes. Vaginal pH strip test (pH > 4.5). If drops of potassium hydroxide solution are applied on the speculum, a fishy smell can be provoked (KOH-test). Some patients with positive test results do not have symptoms. Findings of bacterial vaginosis can be normal in asymptomatic postmenopausal women.


Not necessary.


Symptoms usually wax and wane; may last some days to weeks.


During pregnancy, there have been reports associating bacterial vaginosis with premature labour and perinatal infections (chorioamnionitis).


Based on typical clinical features and complementary tests suggestive for bacterial vaginosis.

Differential diagnosis

Vaginal discharge caused by other causes of vulvovaginitis (candida, aerobic and trichomonas vaginitis). If there is discharge from the cervix, genital chlamydia and gonorrhoea should be excluded; in recurrent cases and elderly women, a colposcopy to exclude malignancies.

Prevention & Therapy

Usually not preventable. Recurrences after treatment are common due to the biofilm produced by G. vaginalis. Oral combined contraceptives can reduce recurrence.


Has a tendency to spontaneously subside and treatments are not always necessary. Should be treated during pregnancy because of possible association with perinatal complications.

Effective treatments are a single dose of p.o. metronidazole 2 g or a course of p.o. metronidazole 400-500 mg t.i.d. for 5-7 days.


Not applicable.

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