Basics
Description
- Bacterial vaginosis (BV) is the most common cause of vaginal discharge.
- Accounts for up to 50% of cases of vaginal discharge in women of childbearing age.
- Other common causes of vaginal discharge include:
- Candidal vulvovaginitis
- Trichomoniasis
- BV is caused by an imbalance of the normal flora in the vaginal milieu, leading to the presence of vaginal discharge.
- Vaginitis is inflammation of the vagina resulting in discharge with or without pain.
- Because of the absence of inflammation in BV, the term "vaginosis"¯ is used instead of "vaginitis."¯
Epidemiology
Prevalence
- Prevalence of 5-60% worldwide
- Difficult to estimate exact prevalence as many women are asymptomatic
- Can occur in heterosexual and lesbian women
- Higher prevalence among African American women and women who partner with women
- Prevalence among pregnant women in the USA: 10-35%
Risk Factors
- Vaginal douching
- New sexual partner
- Multiple sexual partners
- Women who have sex with women
- Tobacco use
General Prevention
- Avoiding douching
- Safe sex practices as higher number of sexual partners associated with higher rates of BV
Pathophysiology
- Caused by imbalance of normal flora
- Decrease in lactobacilli and proliferation of other organisms, particularly anaerobic gram-negative rods (see "Etiology"¯)
- Unclear whether initial pathogenic event is overgrowth of anaerobes or decrease in lactobacilli.
- Role of sexual transmission is controversial.
- Higher-risk sex practices (higher number of sexual partners) have been associated with higher rates of BV in both heterosexual and lesbian women.
- However,
- Treating male partners of women with BV is not beneficial.
- Women who are not sexually active can develop BV.
Etiology
- Proliferation of the following organisms in the vaginal milieu:
- Gardnerella vaginalis, most commonly
- Mycoplasma hominis
- Anaerobes such as Mobiluncus, Bacteroides, and Peptostreptococcus species
Associated Conditions
- Increases susceptibility to HIV and other sexually transmitted infections (STIs)
- Complications in pregnancy
- Preterm labor and delivery
- Premature rupture of membranes
- Spontaneous abortion
Diagnosis
- Diagnosis is made by the presence of 3 of the 4 criteria, known as Amsel's criteria (1)[A] (sensitivity = >90%, specificity = 77%):
- Thin, white, homogenous discharge
- Vaginal pH >4.5
- Positive Whiff test (amine odor when potassium hydroxide [KOH] added)
- Presence of clue cells on light microscopy
- Squamous cells with irregular borders secondary to studding of bacteria to cell membrane
- Should account for 20% of cells on wet mount
- Presence of clue cells is single most reliable predictor of BV
History
- Vaginal douching or heavy soap use
- Signs and symptoms:
- Thin, white, homogenous discharge
- Malodorous, "fishy"¯ discharge
- Dyspareunia, dysuria rare
- 50-75% of women may be asymptomatic.
Physical Exam
- Inspection and speculum exam reveals normal vulva, vaginal mucosa, and cervix.
- Signs of mucosal erythema and irritation are typically absent.
- Thin, white, homogenous discharge is present in the vaginal vault.
Tests
Lab
- pH >4.5 (normal = 4.5)
- Light microscopy (see below)
- 10% KOH preparation for Whiff test
- Small amount of vaginal discharge is placed on glass slide
- A drop of KOH is added to slide
- Production of an amine (or "fishy"¯) odor indicates a positive Whiff test
- Gram stain
- Often considered the gold standard (1)[A]
- Presence of small gram-negative rods or gram-variable rods and the absence of longer lactobacilli is highly predictive of BV
- Less convenient for establishing diagnosis in office
- DNA probe (1)[B]
- Commercially available probe that simultaneously detects presence of Candida species, G. vaginalis, and Trichomonas vaginalis from single vaginal swab
- Results within 45 minutes
- Must be performed in the laboratory
- Sensitivity 73-89%, specificity 88-97%
- Does not detect BV that is caused by organisms other than G. vaginalis
- Colorimetric pH and amine card (1)[C]
- Detection of pH >4.7 and presence of vaginal fluid amines
- Rapid diagnosis in office setting
- Sensitivity, 40-89% and specificity, 61-95%
- Screen for STIs if indicated:
- HIV
- Chlamydia
- Gonorrhea
- Trichomoniasis
- Syphilis
- Hepatitis B and C
- Samples for pH, microscopy, DNA probe, and culture should be obtained from the posterior fornix or vaginal wall.
- Obtaining a sample from cervical os may reveal normal cervical mucous.
Diagnostic Procedures/Other
- Light microscopy
- Normal saline wet preparation slide
- Place thin layer of discharge on glass slide
- Add 1 drop of normal saline to slide
- Findings
- Presence of clue cells (≥20% of all cells)
- Absence of lactobacilli
- Scant white blood cells
Differential Diagnosis
- Atrophic vaginitis
- Trichomoniasis
- Candidal vulvovaginitis
- Desquamative inflammatory vaginitis
Treatment
- Treatment is recommended for symptomatic women (1)[A].
- Treatment for asymptomatic women should be considered; however, complications (see "Complications"¯) can occur in patients with untreated BV, particularly in (1)[B]:
- Pregnant women
- Women undergoing gynecologic procedures and/or surgeries
- Women at risk for STIs
Medication
First Line
- Metronidazole: 500 mg PO b.i.d. — 7 days (1)[A]
- Metronidazole gel 0.75%: 5 g intravaginally daily — 5 days
- Clindamycin 2% cream: 5 g intravaginally qhs — 7 days
Second Line
- Clindamycin
- Tablets: 300 mg PO b.i.d. — 7 days
- Ovules: 100 g intravaginally qhs — 3 days
- Bioadhesive cream 2%: 5 g — 1 dose
Additional Treatment
Issues for Referral
Consider referral to an obstetrician or a gynecologist if no resolution of symptoms after treatment.
Complementary and Alternative Medicine
- Small studies have demonstrated that lactobacillus suppositories and oral lactobacillus may decrease recurrent BV.
- Lactobacillus suppositories 1 capsule intravaginally for 7 days — 2 courses, given 7 days apart (2)[C]
- Oral yogurt with live Lactobacillus acidophilus cultures may reduce episodes of BV (3)[C]
- Twice daily yogurt douches — 7 days may be an effective treatment in pregnant women (3)[C].
In-Patient Considerations
Treatment is primarily outpatient.
Ongoing Care
Follow-Up Recommendations
Cure rate with first-line medication is >90%; slightly lower with second-line regimens.
Patient Monitoring
Consider screening for STIs
Patient Education
- Avoid douching or heavy soap use
- Studies do not demonstrate reduced rates of recurrence in women whose partners were also treated for BV.
Complications
- Untreated BV is associated with higher risks of the following:
- Transmission of HIV and other STIs
- Complications in patients undergoing gynecologic procedures or surgeries
- Vaginal cuff cellulitis
- Pelvic inflammatory disease
- Endometritis
- Complications in pregnancy (see "Pregnancy"¯)
- Recurrence
- Occurs in approximately 30% within first 3 months after treatment
- Unclear if recurrence occurs secondary to:
- Failure to restore balance of normal flora because of organisms resistant to current antibiotic regimens
- Failure to treat an unidentified pathogen
- Reinfection from untreated partners
- Hygiene practices that disrupt the balance of normal flora
- OR a combination of above factors
- Regimens
- Treatment with metronidazole 500 mg PO b.i.d. — 10-14 days
- Consider suppression with metronidazole 0.75% vaginal gel — 10 days then biweekly — 4-6 months
- Consider adding boric acid 600 mg vaginally — 21 days to oral metronidazole regimen to improve rate of cure
- In pregnancy, BV has been associated with the following:
- Preterm delivery
- Preterm labor
- Premature rupture of membranes
- Spontaneous abortion
- CDC recommends treatment of symptomatic pregnant women (1)[A].
- CDC no longer discourages use of oral metronidazole in first trimester as has not been associated with birth defects.
- Metronidazole 500 mg po b.i.d. or 250 mg t.i.d. — 7 days
- Clindamycin 300 mg b.i.d. — 7 days
- Treatment of asymptomatic pregnant women does not improve pregnancy outcomes.
- Therefore, CDC recommends against routine treatment of asymptomatic pregnant women at average risk for preterm labor.
- Detection and treatment of BV should therefore ideally occur prior to pregnancy.
- Pregnant women at high risk for preterm labor
- High risk usually defined as prior preterm delivery.
- Screening is an option, but the US Preventative Services Task Force (USPSTF) does not recommend for or against routine screening given insufficient evidence (4)[C].
- Breastfeeding women
- Women should withhold breastfeeding during treatment with metronidazole and for 12-24 hours after last dose to reduce the exposure of infant to metronidazole.
- Clindamycin 300 mg bid — 7 days is alternative although infant should be monitored for antibiotic-associated colitis.
References
1Workowski KA, Berman S Sexually transmitted diseases treatment guidelines, 2010. MMWR Recomm Rep. 2010;59:1-110. [View Abstract]2Ya W, Reifer C, Miller LE Efficacy of vaginal probiotic capsules for recurrent bacterial vaginosis: A double-blind, randomized, placebo-controlled study. Am J Obstet Gynecol. 2010;203:120. [View Abstract]3Van Kessel K, Assefi N, Marrazzo J. Common complementary and alternative therapies for yeast vaginitis and bacterial vaginosis: A systematic review. Obstet Gynecol Surv. 2003;58:351-358. [View Abstract]4 The guide to clinical preventative services 2010-2011. AHRQ Publication No. 10-05145, 2010.
Additional Reading
1Allsworth JE, Peipert JF Prevalence of bacterial vaginosis: 2001-2004 National Health and Nutrition Examination Survey data. Obstet Gynecol. 2007;109:114-120. [View Abstract]2Bradshaw CS, Morton AN, Garland SM. Higher-risk behavioral practices associated with bacterial vaginosis compared with vaginal candidiasis. Obstet Gynecol. 2005;106:105-114. [View Abstract]3Hale TW Drug therapy and breastfeeding: Antibiotics, analgesics, and other medications. NeoReviews. 2005;6(5):e233.4Turovskiy Y, Noll KS, Chikindas ML. The aetiology of bacterial vaginosis. J Appl Microbiol. 2011;110(5):1105-1128. [View Abstract]
Additional Reading see also
Absence of lactobacilli and clue cells: Obliteration of sharp borders of squamous cells secondary to studding of bacteria to cell membrane.
Codes
ICD9
- 616.10 Vaginitis and vulvovaginitis, unspecified
- 623.5 Vaginal discharge NOS
ICD10
- N76.1 Subacute and chronic vaginitis
- N89.8 Other specified noninflammatory disorders of vagina
SNOMED
- 419760006 bacterial vaginosis (disorder)
- 271939006 vaginal discharge (finding)
- 30800001 vaginitis (disorder)
Clinical Pearls
- Bacterial vaginosis (BV) is caused by an imbalance of vaginal flora.
- Overgrowth of Gardnerella vaginalis is most common.
- Treatment of all symptomatic women is recommended.
- Treatment of asymptomatic women should be considered as BV is associated with higher transmission rates of HIV, postoperative infections, and complications in pregnancy.
- Treatment of pregnant women does not decrease risk of preterm labor; therefore, identification and treatment of BV should ideally occur prior to pregnancy.