Bacterial Vaginosis

 

Bacterial vaginosis (BV) is characterized by an overgrowth of predominantly anaerobic organisms (such as Gardnerella vaginalisPrevotella species, Mycoplasma hominis, and Mobiluncus species) and a loss of lactobacilli. The vagina loses its normal acidity, and vaginal pH increases to greater than 4.5.  BV is the most common cause of vaginal discharge in women of reproductive age

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Contributory factors

Factors that increase the risk of developing BV are:

  • Being sexually active — BV is not sexually transmitted but being sexually active or having concurrent sexually transmitted infections increases the risk of developing BV
  • Recent change in sexual partner
  • Certain sexual practices (for example receptive oral sex)
  • Vaginal douching, bubble baths
  • Copper intra-uterine device
  • Increase in vaginal pH, for example due to menstruation or presence of semen
  • Smoking

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Factors that reduce the risk of developing BV are:

  • Combined oral contraceptive pill
  • Condoms
  • Circumcised partner

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Signs and symptoms

NOTE Approximately 50% of women with bacterial vaginosis (BV) are asymptomatic

When symptoms are present, BV is characterized by:

  • a fishy-smelling vaginal discharge
  • a thin, white, homogeneous discharge coating the walls of the vagina and vestibule
    • the discharge is not specific for BV but supports the diagnosis
  • a pH of the vaginal fluid greater than 4.5

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NOTE Bacterial vaginosis is not usually associated with soreness, itching, or irritation.  If these symptoms are present, consider co-infection with or other diagnoses, such as trichomoniasis or candidiasis

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Investigations for non-pregnant women

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:

  1. The woman is not at high risk of a sexually transmitted infection (STI)
    1. 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
  2. The woman does not have symptoms of other conditions causing vaginal discharge (for example itch, abdominal pain, abnormal bleeding, dyspareunia, or fever)
  3. The woman is not post-natal, post-miscarriage, or post-termination
  4. Symptoms have not developed after a gynaecological procedure
  5. Symptoms have not recurred soon after treatment for BV or persisted following treatment for BV
  6. The woman is not pregnant

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If empirical treatment is not considered appropriate, or if the diagnosis is uncertain:

  1. Perform a speculum examination
  2. If pH paper is available, test the pH of the vaginal fluid
  3. Take a high vaginal swab (or use a self-taken low vaginal swab) for Gram staining and to exclude other causes of vaginal discharge
  4. If the woman is at high risk of an STI, specimens for chlamydia and gonorrhoea should also be sent

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Investigations for pregnant women

NOTEExamination and further tests are recommended in all pregnant women with characteristic symptoms of bacterial vaginosis

  1. Perform a speculum examination (unless the woman has a low-lying placenta)
  2. If pH paper is available, test the pH of the vaginal fluid
  3. Take a high vaginal swab for Gram staining and to exclude other causes of vaginal discharge
  4. If the woman is at high risk of an STI, specimens for chlamydia and gonorrhoea should also be sent

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Measuring and interpreting the pH

  1. Obtain a sample of vaginal fluid on a cotton-tipped swab either as a blind vaginal swab, or via a speculum from as high up the vagina as possible
    1. When using a speculum to obtain the swab, swab the lateral wall and not the posterior fornix, as the latter may collect secretions from the cervix, which has a naturally higher pH (the presence of blood or semen can also raise the pH)
  2. Roll the swab over the pH paper
  3. Measure the pH by comparing the colour of the moist test section of pH paper against the graded standard
    1. A pH greater than 4.5 is suggestive of, but it is not specific for the diagnosis of bacterial vaginosis; increased vaginal pH can also indicate other conditions, such as trichomoniasis

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Management - non-pregnant women

Asymptomatic women

NOTE:  Women with asymptomatic bacterial vaginosis do not usually require treatment, unless they are undergoing termination of pregnancy

Women with asymptomatic bacterial vaginosis who are currently progressing with a pregnancy may require treatment - see section below

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Treatment

  1. Oral metronidazole is the treatment of choice
    1. A dose of 400 mg twice a day for 5 to 7 days is recommended
    2. If adherence to treatment is an issue, a single oral dose of 2 g may be used, although this is associated with a higher relapse rate
  2. Intravaginal metronidazole gel or intravaginal clindamycin cream are alternative choices if the woman prefers topical treatment or cannot tolerate oral metronidazole:
    1. Intravaginal metronidazole gel 0.75% once a day for 5 days (off-label for women aged less than 18 years), or
    2. Intravaginal clindamycin cream 2% once a day for 7 days
  3. Oral clindamycin and oral tinidazole are alternatives but are less preferred

NOTE:  A test of cure is not required if symptoms resolve

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Persistent symptoms

NOTE:  Persistent symptoms are most likely to be due to misdiagnosis or to poor adherence to treatment or excessive use of products which increase the vaginal pH (for example vaginal douching, antiseptics, bubble baths, or shampoos in the bath)

If symptoms persist after initial treatment:

  1. Reconsider the diagnosis
    1. Perform a speculum examination and take swabs if this has not been previously done
  2. Check for adherence to treatment
  3. Ensure that the current episode is adequately managed
    1. If a single 2 g dose of metronidazole has previously been used, a 7-day course of 400 mg metronidazole twice daily can be tried
    2. If intravaginal preparations have previously been used, a course of oral metronidazole can be tried
  4. In the unlikely event that a woman with confirmed bacterial vaginosis (BV) has not responded to a 7-day course of oral metronidazole(and you are confident that she has adhered to the treatment regimen), discuss with a gynaecologist or genito-urinary medicine specialist regarding further treatment

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For persistent BV in women with an intrauterine contraceptive device, consider removing the device and advising the use of an alternative form of contraception

Routine screening and treatment of male partners is not indicated, but consider testing and treating the female partner in a same-sex relationship

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Recurrent symptoms

  1. Advise the woman that recurrence of symptoms is common
  2. Reconsider the diagnosis of bacterial vaginosis (BV)
    1. Perform a speculum examination and take swabs if this has not been previously done
  3. Treat the current episode with a 7-day course of oral metronidazole
  4. Advise the woman that it may be beneficial to avoid vaginal douching, antiseptics, bubble baths, or shampoos in the bath
  5. If the diagnosis is confirmed and symptoms recur frequently (at least four times a year) despite adequate management in primary care, and symptoms are adversely affecting the woman:
    1. Consider prescribing metronidazole vaginal gel as suppressive treatment (off-label use) if experienced in treating recurrent BV in primary care
    2. Otherwise discuss management with a gynaecologist or genito-urinary medicine specialist

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Management - pregnant women

Treatment

NOTE:  Offer treatment to all pregnant women with symptomatic bacterial vaginosis (BV)

NOTE Women who are pregnant should not be offered routine screening for BV. However, if a pregnant woman is incidentally found to have BV and has no symptoms, discuss with the woman's obstetrician whether treatment is appropriate

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  1. Oral metronidazole is the treatment of choice
    1. A dose of 400 mg twice a day for 5 to 7 days is recommended
    2. High-dose regimens (single oral dose of 2 g) are not recommended during pregnancy
  2. Intravaginal metronidazole gel or intravaginal clindamycin cream are alternative choices for achieving cure if the woman prefers a topical treatment or is unable to tolerate oral metronidazole:
    1. Intravaginal metronidazole gel 0.75% once a day for 5 days, or
    2. Intravaginal clindamycin cream 2% once a day for 7 days
  3. Oral clindamycin may also be considered, but is less preferred
  4. Testing should be repeated after 1 month if the women is still symptomatic

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Persistent or recurrent symptoms

If symptoms persist or recur after initial treatment:

  1. Reconsider the diagnosis of bacterial vaginosis
  2. Check adherence with treatment
  3. Ensure that the current episode is adequately managed
    1. Oral metronidazole 400–500 mg twice a day for 7 days is generally considered to be the most effective treatment
  4. Seek advice regarding further treatment from the woman's obstetrician or a genito-urinary physician

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Microbiology

Please send cultures to the Microbiology Department at East Kent Hospitals (find details here)

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