Bacterial Vaginosis
Overview
- Most common cause of abnormal vaginal discharge in women of childbearing age
- Up to 50% are asymptomatic
- While BV is not considered an STI BV can be acquired through sexual activity.
Cause
A polymicrobial clinical syndrome caused by a profound change in vaginal microbiota from a Lactobacillius dominant state to one with high diversity and loads of anaerobic bacteria including Gardnerella vaginalis, Atopobium vaginae, Mobiluncus spp, Prevotella spp, and other BV-associated bacteria (BVAB). This change is accompanied by a rise in vaginal pH and increased amines which produce odour. Studies have identified a polymicrobial biofilm adherent to vaginal epithelial cells of women with BV which is absent in controls.
Clinical presentation
Symptoms |
Offensive ‘fishy’ vaginal discharge |
Thin white homogenous discharge |
Can cause mild vulval irritation |
Complications |
Bacterial vaginosis is associated with increased risk of spontaneous abortion, premature labour, chorioamnionitis, postpartum endometritis and pelvic inflammatory disease (PID); especially following termination of pregnancy (TOP), intra-uterine device (IUD) insertion or other instrumentation). BV is associated with a 2-3 fold increased risk of acquiring STIs including chlamydia, gonorrhoea, herpes simplex type 2 and HIV infection, and increases the risk of HIV transmission to male partners. |
Special considerations
- Approximately 50% of women are asymptomatic.
- Bacterial vaginosis may coexist with other conditions such as trichomoniasis and other STIs.
- Despite the association between bacterial vaginosis and pelvic inflammatory disease (PID) following termination of pregnancy (TOP), intra-uterine device (IUD) insertion or other instrumentation, bacterial vaginosis screening recommendations before invasive procedures have not been determined.
Diagnosis
The diagnosis of BV is usually made in clinical settings using the Amsels or modified Amsels criteria;
A diagnosis is made if 3 or 4 of the following criteria are present:
1. Thin white/grey homogenous discharge –
2. Vaginal fluid raised pH (pH>4.5) – using pH paper
3. Genital malodour
4. Clue cells on gram stain – this last criterion will be able to be reported by the laboratory on the slide collected below.
Test | Site/Specimen | Consideration |
---|---|---|
Microscopy of high vaginal smear | High vaginal swab | In general practice, prepare a non-stained microscopy slide at the bedside and send to the laboratory with a request for Gram stain and microscopy. |
Whiff test | Vaginal fluid | Odour during examination indicates a positive whiff test. |
pH | Vaginal fluid | Normal vaginal pH < 4.5. pH >4.5 indicative of bacterial vaginosis. |
Specimen collection
Urethral swabs for microscopy should be collected when the patient has not urinated for at least 1 hour and only if the patient has frank urethral discharge. Squeeze the urethra to express the discharge and collect on urethral swab. It is not necessary to insert the swab into the urethra. Vaginal swab: instruct the patient to insert the swab into the vagina like a tampon and then remove and place into the transport tube. Rectal swab: instruct the patient to insert the swab into the anal canal 2-4cms and then remove and place into the transport tube. FPU (First pass urine): Collect approximately 20 ml (1/3 of the standard urine jar) of the first part of the urine stream in a specimen jar at the time you are consulting the patient. The patient does not need to have held their urine for more than 20 minutes prior to specimen collection. A midstream urine (MSU) or early morning specimen (i.e. first void urine) are not required for NAAT. Click here for information on how to describe self-collection technique to a patient.Clinician collected for NAAT/culture/microscopy
Rectal swabs should be collected by inserting a sterile swab 2-4cms into the anal canal and moving the swab gently side to side for 10-20 seconds.
Pharyngeal swabs should be collected from the tonsils and oropharynx.
High vaginal swab of vaginal discharge smeared onto a glass slide, air dried and sent for microscopy. Swab inserted into transport medium for culture.Self-collection of samples for NAAT testing
See STI Atlas for images.
Management
Principal Treatment Option | ||
---|---|---|
Situation | Recommended | Alternative |
Symptomatic bacterial vaginosis | Metronidazole 400mg PO, BD with food for 7 days. OR Metronidazole 0.75% gel 5g, intravaginally nocte for 5 nights (not on PBS). OR Clindamycin 2% vaginal cream 5g, intravaginally nocte for 7 days (not on PBS). OR Clindamycin 300mg PO, BD for 7 days. |
Metronidazole 2g PO, stat. |
Women undergoing gynaecological procedures |
Metronidazole 400mg PO, BD with food for 5 days. |
Metronidazole 2g PO, stat. |
Treatment advice
Treatment is predominantly aimed at alleviating symptoms and recurrence. Treatment is indicated in:
1. symptomatic women
2. Women undergoing an invasive upper genital tract procedure. (Oral treatment is recommended)
3. women requesting treatment
- If a patient has an intrauterine device (IUD), leave IUD in place and treat as recommended. Seek specialist advice as needed.
- Stat dose and short duration regimens are associated with higher rates of recurrence.
- Recurrence is common
Other immediate management
- Avoid vaginal douching
- Contact tracing is not required.
Special treatment situations
Situation | Recommended | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Breastfeeding | Consider intravaginal treatment. Metronidazole may affect taste of breast milk; avoid high doses in breastfeeding. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Pregnant women
For more information go to the Therapeutic Goods Association's Prescribing medicines in pregnancy database and/or seek specialist advice. ![]() |
Treatment for pregnant women is the same as the principle treatment options for non-pregnant women. Treatment is recommended for all pregnant women with symptoms, although the evidence is conflicting in terms of the benefits of treatment on the outcomes of pregnancy. Women undergoing termination of pregnancy should be treated to reduce risk of post-termination PID. |
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Allergy to principal treatment choice |
If allergy to nitroimidazoles, use clindamycin. |
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Alcohol |
Alcohol should be avoided with metronidazole use due to the possibility of a disulfiram-like action. There are no data on the risks of alcohol with intravaginal metronidazole gel, but it is not recommended at present. |
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Intravaginal preparations |
May affect condom integrity. |
Contact tracing
- Contact tracing is not required
- There is currently no evidence to support routine treatment of male sexual partners
- As concordance for bacterial vaginosis is high in female partnerships, assessment of female partners is recommended (women who have sex with women (WSW)).
Follow up
Not required.
Test of Cure (TOC): Not required
Retesting: If symptoms persist or recur, as it is important to confirm diagnosis and establish a pattern. Consider testing for other STIs, if not undertaken at first presentation, or retesting post the window period.
Auditable outcomes
- 100% of symptomatic patients are treated
- 100% of women undergoing an invasive upper genital tract procedure are treated.