• Approximately 50% of women with bacterial vaginosis (BV) are asymptomatic.
• When symptoms are present, BV is characterized by a fishy-smelling vaginal discharge.
• Examination may reveal a thin, white, homogeneous discharge coating the walls of the vagina and vestibule.
• The characteristic appearance of the discharge is not specific for BV but supports the diagnosis.
• If the appearance of the discharge is not characteristic, consider other diagnoses, such as trichomoniasis or candidiasis.
• Bacterial vaginosis is not usually associated with soreness, itching, or irritation.
• If these symptoms are present, consider other diagnoses, such as trichomoniasis or candidiasis. (There are CKS topics on Vaginal discharge, Trichomoniasis, and Candida - female genital.)
• The pH of the vaginal fluid is greater than 4.5.

These recommendations are based on guidelines from the British Association for Sexual Health and HIV on the management of bacterial vaginosis [BASHH, 2006] and guidance from the UK Health Protection Agency on the management of abnormal vaginal discharge in women [HPA, 2008].

• Examination and further tests may be omitted and empirical treatment for bacterial vaginosis (BV) started in women with characteristic symptoms of BV if all the following apply:
• The woman is not at high risk of a sexually transmitted infection (STI).
• Women are at increased risk of an STI if they are younger than 25 years of age, or have had a new sexual partner in the last 12 months, or more than one sexual partner in the last 12 months.
• The woman does not have symptoms of other conditions causing vaginal discharge (for example itch, abdominal pain, abnormal bleeding, dyspareunia, or fever).
• The woman is not post-natal, post-miscarriage, or post-termination.
• Symptoms have not developed after a gynaecological procedure.
• Symptoms have not recurred soon after treatment for BV or persisted following treatment for BV.
• The woman is not pregnant (see When and how to test pregnant women).
• If empirical treatment is not considered appropriate, or if the diagnosis is uncertain:
• Perform a speculum examination.
• If pH paper is available, test the pH of the vaginal fluid.
• Take a high vaginal swab (or use a self-taken low vaginal swab) for Gram staining and to exclude other causes of vaginal discharge.
• Samples should be placed in transport media (such as Amie's or Stuart's medium). A Gram stain for mixed flora suggestive of BV and a trichomoniasis culture should be requested from the laboratory.
• If there is a delay in transportation, the swab should be refrigerated at 4°C for no longer than 48 hours.
• If the woman is at high risk of an STI, specimens for chlamydia and gonorrhoea should also be sent, according to local laboratory procedures.
• For further information, see the CKS topic on Vaginal discharge.

Empirical management of bacterial vaginosis

• The recommendation to treat certain women without further examination and tests is based on expert opinion and is consistent with UK guidelines for the management of abnormal vaginal discharge outside of genito-urinary medicine settings [FFPRHC and BASHH, 2006; RCGP and BASHH, 2006].

Examination and investigation

• Recommendations for examination and investigation are consistent with UK guidelines for the management of abnormal vaginal discharge outside of genito-urinary medicine settings [FFPRHC and BASHH, 2006; RCGP and BASHH, 2006].
• Recommendations for transport and storage of swabs are consistent with UK guidelines on testing for sexually transmitted infections in primary care [BASHH, 2004; FFPRHC and BASHH, 2006; RCGP and BASHH, 2006].

• Examination and further tests are recommended in all pregnant women with characteristic symptoms of bacterial vaginosis.
• Perform a speculum examination (unless the woman has a low-lying placenta).
• If pH paper is available, test the pH of the vaginal fluid.
• Take a high vaginal swab for Gram staining and to exclude other causes of vaginal discharge.
• Samples should be placed in transport media (such as Amie's or Stuart's medium). A Gram stain for mixed flora suggestive of BV and a trichomoniasis culture should be requested from the laboratory.
• If there is a delay in transportation, the swab should be refrigerated at 4°C for no longer than 48 hours.
• If the woman is at high risk of a sexually transmitted infection, specimens for chlamydia and gonorrhoea should also be sent, according to local laboratory procedures.
• For further information, see the CKS topic on Vaginal discharge.

Examination and testing in pregnant women

• CKS found no guidelines specifically regarding examination and investigation in pregnant women, but making an accurate diagnosis and excluding other causes seem prudent, given the potential adverse outcomes of bacterial vaginosis (BV) in pregnancy and that the recommended treatment is with antibiotics.
• CKS expert reviewers agree that examination and testing should always be done in pregnant women with BV, because the symptoms and clinical signs of BV are less reliable in pregnancy and because of the altered risk-to-benefit ratio.
• Recommendations for examination and investigations are consistent with UK guidelines for the management of abnormal vaginal discharge outside of genito-urinary medicine settings [FFPRHC and BASHH, 2006; RCGP and BASHH, 2006].

Transport and storage of swabs

• Recommendations for transport and storage of swabs are consistent with UK guidelines on testing for sexually transmitted infections in the primary care setting [BASHH, 2004; FFPRHC and BASHH, 2006; RCGP and BASHH, 2006].

• Obtain a sample of vaginal fluid on a cotton-tipped swab (via a speculum) from as high up the vagina as possible.
• Swab the lateral wall and not the posterior fornix, as the latter may collect secretions from the cervix, which has a naturally higher pH.
• Roll the swab over the pH paper.
• Measure the pH by comparing the colour of the moist test section of pH paper against the graded standard.
• A pH greater than 4.5 is consistent with a diagnosis of bacterial vaginosis.
• Although a pH greater than 4.5 is supportive of the diagnosis, it is not specific for bacterial vaginosis; increased vaginal pH can also indicate other conditions, such as trichomoniasis.

These recommendations are based on Scottish regional guidelines on the primary care management of vaginal discharge [NHS Lothian, 2008].