bacterial vaginosis

Bacterial vaginosis (BV) describes an overgrowth of predominately anaerobic organisms such as Gardnerella vaginalis. This leads to a consequent fall in lactic acid producing aerobic lactobacilli resulting in a raised vaginal pH.

Whilst BV is not a sexually transmitted infection it is seen almost exclusively in sexually active women.

Features
vaginal discharge: 'fishy', offensive
asymptomatic in 50%

Amsel's criteria for diagnosis of BV - 3 of the following 4 points should be present
thin, white homogenous discharge
clue cells on microscopy: stippled vaginal epithelial cells
vaginal pH > 4.5
positive whiff test (addition of potassium hydroxide results in fishy odour)

Management
oral metronidazole for 5-7 days
70-80% initial cure rate
relapse rate > 50% within 3 months
the BNF suggests topical metronidazole or topical clindamycin as alternatives

Bacterial vaginosis in pregnancy
results in an increased risk of preterm labour, low birth weight and chorioamnionitis, late miscarriage
it was previously taught that oral metronidazole should be avoided in the first trimester and topical clindamycin used instead. Recent guidelines however recommend that oral metronidazole is used throughout pregnancy. The BNF still advises against the use of high dose metronidazole regimes

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