Bacterial Vaginosis

BV |

Overview

  • Most common cause of abnormal vaginal discharge in women of childbearing age
  • Up to half of the women affected may not experience symptoms
  • Epidemiological studies show a strong association with sexual activity but there is insufficient evidence currently to support sexual transmission.

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 sppPrevotella spp, and other BV-associated bacteria (BVAB). This change is accompanied by a rise in vaginal pH and increased amines which produce odour. Recent studies have identified a bacterial biofilm on the vaginal walls of women with BV.

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.

TestSite/SpecimenConsideration
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

Clinician collected |
Self-collection
 

See STI Atlas for images.

Management

Principal Treatment Option
SituationRecommendedAlternative
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.
OR
Tinidazole 2g PO, stat.

Women undergoing gynaecological procedures

Metronidazole 400mg PO, BD with food for 5 days. 
OR 
Clindamycin 300mg PO, BD for 7 days.

Metronidazole 2g PO, stat.
OR
Tinidazole 2g PO, stat.

Treatment advice

  • Treatment is predominantly aimed at alleviating symptoms and recurrence following recommended treatment is common. Therefore, treatment is not indicated for asymptomatic women unless requested, or the patient is undergoing an invasive upper genital tract procedure.
  • Oral treatment is recommended for women before undergoing an invasive gynaecological procedure.
  • 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.

Other immediate management

  • Avoid vaginal douching
  • Contact tracing is not required.

Special treatment situations

SituationRecommended
Breastfeeding Consider intravaginal treatment. Metronidazole may affect taste of breast milk; avoid high doses in breastfeeding.
Pregnant women 
pregnancy
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.
Allergy to principal treatment choice

If allergy to nitroimidazoles, use clindamycin.

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.

Intravaginal preparations

May weaken condoms.

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 if symptoms resolve.

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.
Last Updated: Tuesday, 22 March 2016