Recommendation Statement
U.S. Preventive Services Task Force (USPSTF)
- The U.S. Preventive Services Task
Force (USPSTF) makes recommendations about preventive care services for
patients without recognized signs or symptoms of the target condition.
- It bases its recommendations on a
systematic review of the evidence of the benefits and harms and an assessment
of the net benefit of the service.
- The USPSTF recognizes that
clinical or policy decisions involve more considerations than this body of
evidence alone. Clinicians and policymakers should understand the evidence
but individualize decisionmaking to the specific patient or situation.
This recommendation statement was first published in Annals of Internal Medicine. Select for copyright information.
Contents
Summary of Recommendations and Evidence
Clinical Considerations
Other Considerations
Discussion
Recommendations of Others
References
Members of the USPSTF
Summary of Recommendations and Evidence
- The USPSTF recommends against screening for bacterial
vaginosis in asymptomatic pregnant women at low
risk for preterm delivery. (This is a grade "D" recommendation.)
- The USPSTF concludes that the current evidence is
insufficient to assess the balance of benefits and harms of
screening for bacterial vaginosis in asymptomatic pregnant
women at high risk for preterm delivery. (This is an "I" statement.)
|
Go to the Clinical Considerations section for a discussion
of risk assessment and suggestions for practice. Go to the Figure for a summary of this recommendation and its impact on clinical practice. Go to
Table 1 for a description of the USPSTF grades and Table 2 for a description of
the USPSTF classification of levels of certainty regarding net benefit.
Rationale:
Importance
The associations between bacterial vaginosis and adverse
pregnancy outcomes, such as preterm delivery, are
well documented.
Detection
Good-quality evidence indicates that screening tests
(the Amsel clinical criteria or Gram stain) can detect bacterial
vaginosis.
Benefits of Detection and Early Intervention
Asymptomatic Pregnant Women at Low Risk for Preterm Delivery. No direct evidence indicates that screening for
bacterial vaginosis reduces adverse health outcomes in
asymptomatic pregnant women at low risk for preterm delivery.
Good evidence indicates that treatment of bacterial
vaginosis in these women lacks benefit.
Asymptomatic Pregnant Women at High Risk for Preterm
Delivery. No direct evidence indicates that screening
for bacterial vaginosis reduces adverse health outcomes in
asymptomatic pregnant women at high risk for preterm
delivery. Evidence from good-quality studies is conflicting
with respect to the benefits of treating bacterial vaginosis.
Harms of Detection and Early Treatment
Asymptomatic Pregnant Women at Low Risk for Preterm
Delivery. Evidence is poor (because studies are lacking) for
harms of screening for bacterial vaginosis in asymptomatic
pregnant women at low risk for preterm delivery. Evidence
is fair that false-positive results from screening lead to
harms due to treatment.
Asymptomatic Pregnant Women at High Risk for Preterm
Delivery. Evidence is poor (because studies are lacking)
for harms of screening for bacterial vaginosis in
asymptomatic pregnant women at high risk for preterm
delivery. Studies on the harms of treatment have conflicting
results.
USPSTF Assessment. The USPSTF concludes that for
asymptomatic pregnant women at low risk for preterm delivery,
there is moderate certainty that screening for bacterial
vaginosis has no net benefit.
The USPSTF concludes that for asymptomatic pregnant
women at high risk for preterm delivery, the evidence
is conflicting and the balance of benefits and harms cannot
be determined.
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Clinical Considerations
Patient Population under Consideration
This recommendation addresses screening for bacterial
vaginosis in asymptomatic pregnant women.
Risk Assessment
Several factors have been associated with increased risk
for preterm delivery. All of these associations are small to
moderate. These factors include, but are not limited to,
African-American race or ethnicity, body mass index less
than 20 kg/m2, previous preterm delivery, vaginal bleeding,
a short cervix (<2.5 cm), pelvic infection, and bacterial
vaginosis. These factors can act in isolation or in combination.
Furthermore, bacterial vaginosis in pregnancy is
more common among African-American women, women
of low socioeconomic status, and those who have previously
delivered low-birthweight infants. For the purpose of
the current recommendation, women were considered to
be at low risk if they had no previous preterm delivery or
other risk factors for preterm delivery (often these were
nulliparous women). Women were considered to be at
high risk if they had a previous preterm delivery.
Screening Tests
Bacterial vaginosis is diagnosed by using the Amsel
clinical criteria or Gram stain. With the Amsel criteria, the
clinical diagnosis is made by fulfilling 3 of 4 criteria: vaginal
pH greater than 4.7, the presence of clue cells on wet
mount, thin homogeneous discharge, and amine "fishy
odor" when potassium hydroxide is added to the discharge.
Suggestions for Practice
This recommendation statement addresses screening for
bacterial vaginosis in asymptomatic women. Treatment of
symptomatic cases should be based on the clinical situation.
Treatment
Oral metronidazole and oral clindamycin, as well as
vaginal metronidazole gel or clindamycin cream, are used
to treat bacterial vaginosis. The optimal treatment regimen
for pregnant women with bacterial vaginosis is unclear.
Refer to the Centers for Disease Control and Prevention
Web site for current treatment recommendations (www.cdc.gov/std/treatment/2006/vaginal-discharge.htm#vagdis2).
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Other Considerations
Research Needs
There are several evidence gaps in the literature on screening
and treating bacterial vaginosis in asymptomatic pregnant
women. A critical gap in the evidence exists in demonstrating
a benefit of treatment in asymptomatic pregnant women at
increased risk for preterm delivery. Available evidence on
treatment benefit is conflicting. Additional research is needed
to evaluate the benefit of screening and treating asymptomatic
bacterial vaginosis in women at highest risk for preterm delivery.
Research is also needed to assess which screening tests
providers use to diagnose bacterial vaginosis in clinical practice
and the accuracy of these tests. Finally, continued research is
needed to determine the optimal treatment regimen for bacterial
vaginosis.
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Discussion
Burden
of Disease
Bacterial vaginosis is the most common lower genital tract
syndrome among women of reproductive age. It involves
an imbalance in the vaginal bacterial ecosystem, with a
decrease in hydrogen peroxide–producing lactobacilli and
an increase in Gardnerella vaginalis, anaerobes, and mycoplasmas.
Studies have documented an association between
bacterial vaginosis and the adverse pregnancy outcome of
preterm delivery. This epidemiologic evidence has been
used as a rationale for screening asymptomatic pregnant
women for bacterial vaginosis.
The literature demonstrates a prevalence of bacterial vaginosis
ranging from 9% to 23% in studies conducted in academic
medical centers or public hospitals. The prevalence of
bacterial vaginosis in pregnant women in community clinical
settings is not well studied. Bacterial vaginosis in pregnancy is
more common among African-American women, women of low socioeconomic status, and women who have previously
delivered low-birthweight infants.
The natural history of bacterial vaginosis in pregnant
women has shown that up to 50% of cases resolve spontaneously
during pregnancy. Because bacterial vaginosis may
not continue throughout pregnancy, whether to screen and
treat multiple times, and optimal screening intervals, are
not known.1
Scope of Review
The USPSTF updated its 2001 recommendation on
bacterial vaginosis. The goal was to review the literature
and to identify new evidence addressing previously identified
gaps, such as the characterization of patients most
likely to benefit from screening and the optimal timing of
screening and treatment on pregnancy outcomes.
Accuracy of Screening Tests
Bacterial vaginosis is diagnosed by using the Amsel clinical
criteria or Gram stain. The reliability of the Amsel clinical
criteria in community practice is unknown. Gram stain of
vaginal discharge may be a more reliable means of diagnosing
bacterial vaginosis and offers the added ability to quantify and
classify bacterial load. As a result, Gram stain has been the
primary means used to diagnose bacterial vaginosis in research
studies. However, Gram stain is less commonly used in clinical
practice because of the need for laboratory facilities and
the delay in receiving diagnostic results.1
No studies of diagnostic assessment in the clinical
practice setting were found in the literature. Most studies
compared the application of all Amsel clinical criteria with
Gram stain in a research setting. In the 2001 USPSTF
review, comparisons of the Amsel clinical criteria with
Gram stain yielded sensitivities from 62% to 97% and
specificities from 66% to 95%, with Gram stain as the
criterion standard in diagnosing bacterial vaginosis.2
The 2001 USPSTF evidence review stated that the
preferred screening test would predict pregnancy outcomes
with the most accuracy. The current update identified
studies that evaluated diagnostic tests in predicting preterm
birth.1 A poor-quality meta-analysis (11 studies) showed
no difference in accuracy between clinical criteria and
Gram stain in preterm delivery.3
Effectiveness of Early Detection and Treatment
Because the evidence is poor, there is no known benefit
of early detection in either low-risk or high-risk,
asymptomatic pregnant women.
The USPSTF found good evidence of a lack of benefit
from treatment in low-risk, asymptomatic pregnant
women. Randomized clinical trials of good quality pooled
with 2001 report data showed no treatment effects for
asymptomatic women at low risk for preterm delivery at
less than 37 weeks.1
Randomized, controlled trials of good quality had conflicting
results about treatment benefit in high-risk, asymptomatic
pregnant women. There was statistically significant
heterogeneity among the trials (P < 0.001). Three of the 5
trials reported a statistically significant benefit from treatment,
1 showed a statistically significant harm from treatment, and 1
showed no benefit.4-8
Potential Harms of Screening and Treatment
No studies directly addressed the harms of screening (for
example, increased risk for preterm delivery). The effects of
treatment in women with a misdiagnosis of bacterial vaginosis
have been indirectly studied and were documented in the
2001 review.2 Two studies of women who tested negative
for bacterial vaginosis and received treatment compared with
women who tested negative and were not treated found an
increase in preterm delivery at less than 34 weeks in the group
who tested negative and were treated.7,9 A recent study
also confirmed the potential harm of misdiagnosis (greater
spontaneous preterm delivery at <37 weeks) in women who
tested negative for bacterial vaginosis and were treated versus
the placebo group, but this finding did not reach statistical
significance.10
Estimate of Magnitude of Net Benefit
In low-risk, asymptomatic pregnant women, the
USPSTF found no known benefits of detection and early
treatment and concluded with moderate certainty that screening
has no net benefit. Given the lack of net benefit, the
USPSTF recommends against routine screening for bacterial
vaginosis in low-risk, pregnant women. The results of studies
assessing bacterial vaginosis treatment in high-risk, asymptomatic
pregnant women are conflicting. As a result of this significant
evidence gap, the USPSTF concluded that the evidence
is insufficient to make a recommendation about screening for
bacterial vaginosis in high-risk pregnant women.
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Recommendations of Others
The Centers for Disease Control and Prevention,11
the American College of Obstetricians and Gynecologists,12 the Cochrane Pregnancy and Childbirth Group,13
the British Association for Sexual Health and HIV/Clinical
Effectiveness Group,14 and the American Academy of
Family Physicians make similar recommendations about
screening and treatment of pregnant women with bacterial
vaginosis.15 All recommend against routine screening
for bacterial vaginosis in asymptomatic pregnant women.
With respect to women at high risk for preterm delivery,
the Centers for Disease Control and Prevention, American
College of Obstetricians and Gynecologists, the American
Academy of Family Physicians, and British Association for
Sexual Health and HIV state that there may be high-risk
women for whom screening and treatment may be beneficial.
The Centers for Disease Control and Prevention does
not recommend the use of clindamycin vaginal cream in
the second half of pregnancy.
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References
1. Nygren P, Bougatsos C, Freeman M, Helfand M. Screening and Treatment
for Bacterial Vaginosis in Pregnancy: Systematic Review to Update the 2001 U.S.
Preventive Services Task Force Recommendation Statement. Prepared for the
Agency for Healthcare Research and Quality by the Oregon Evidence-based Practice
Center under Contract No. 290-02-0024. Evidence Synthesis No. 57.
AHRQ Publication No. 08-05106. Rockville, MD: Agency for Healthcare Research
and Quality; 2008.
2.Guise JM, Mahon SM, Aickin M, Helfand M, Peipert JF, Westhoff C.
Screening for bacterial vaginosis in pregnancy. Am J Prev Med 2001;20:62-72.
[PMID: 11306234]
3. Honest H, Bachmann LM, Knox EM, Gupta JK, Kleijnen J, Khan KS. The
accuracy of various tests for bacterial vaginosis in predicting preterm birth:
a systematic review. BJOG 2004;111:409-22. [PMID: 15104603]
4. Carey JC, Klebanoff MA, Hauth JC, Hillier SL, Thom EA, Ernest JM, et al.
Metronidazole to prevent preterm delivery in pregnant women with asymptomatic
bacterial vaginosis. National Institute of Child Health and Human Development
Network of Maternal-Fetal Medicine Units. N Engl J Med 2000;342:534-40. [PMID: 10684911]
5. Odendaal HJ, Popov I, Schoeman J, Grové D. Preterm labour—is Mycoplasma
hominis involved? S Afr Med J 2002;92:235-7. [PMID: 12040954]
6. McDonald HM, O'Loughlin JA, Vigneswaran R, Jolley PT, Harvey JA, Bof
A, et al. Impact of metronidazole therapy on preterm birth in women with
bacterial vaginosis flora (Gardnerella vaginalis): a randomised, placebo controlled
trial. Br J Obstet Gynaecol 1997;104:1391-7. [PMID: 9422018]
7. Hauth JC, Goldenberg RL, Andrews WW, DuBard MB, Copper RL. Reduced
incidence of preterm delivery with metronidazole and erythromycin in
women with bacterial vaginosis. N Engl J Med 1995;333:1732-6. [PMID:
7491136].
8. Morales WJ, Schorr S, Albritton J. Effect of metronidazole in patients with
preterm birth in preceding pregnancy and bacterial vaginosis: a placebocontrolled,
double-blind study. Am J Obstet Gynecol 1994;171:345-7; discussion
348-9. [PMID: 8059811]
9. Vermeulen GM, Bruinse HW. Prophylactic administration of clindamycin
2% vaginal cream to reduce the incidence of spontaneous preterm birth in
women with an increased recurrence risk: a randomised placebo-controlled
double-blind trial. Br J Obstet Gynaecol 1999;106:652-7. [PMID: 10428520]
10. Andrews WW, Goldenberg RL; National Institute of Child Health and
Human Development Maternal-Fetal Medicine Units Network. What we have
learned from an antibiotic trial in fetal fibronectin positive women. Semin Perinatol
2003;27:231-8. [PMID: 12889590]
11. Centers for Disease Control and Prevention (CDC). Sexually transmitted
disease treatment guidelines 2006—Diseases characterized by vaginal discharge.
MMWR Recomm Rep 2006;55(RR-11):50-2. Accessed at www.cdc.gov/std/treatment/2006/vaginal-discharge.htm#vagdis2 on 12 April 2007
12. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin.
Assessment of risk factors for preterm birth. Clinical management guidelines
for obstetrician-gynecologists. Number 31, October 2001. (Replaces Technical
Bulletin number 206, June 1995; Committee Opinion number 172, May
1996; Committee Opinion number 187, September 1997; Committee Opinion
number 198, February 1998; and Committee Opinion number 251, January
2001). Obstet Gynecol 2001;98:709-16. [PMID: 11592272]
13. McDonald H, Brocklehurst P, Parsons J. Antibiotics for treating bacterial
vaginosis in pregnancy. Cochrane Database Syst Review 1998, Issue 4. Art. No.:
CD000262. DOI: 10.1002/14651858.CD000262.pub3. Accessed at www.cochrane.org/reviews/en/ab000262.html on 12 April 2007.
14. British Association for Sexual Health and HIV (BASHH) and the Clinical
Effectiveness Group (CEG). Revised national guideline for the management of
bacterial vaginosis. Accessed at www.bashh.org/guidelines/2006/bv_final_0706.pdf on 29 November 2007.
15. American Academy of Family Physicians (AAFP). Recommendations for
clinical preventive services—bacterial vaginosis. Accessed at www.aafp.org/online/en/home/clinical/exam/a-e.html on 12 April 2007.
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Members of the U.S. Preventive Services Task Force*
Members of the U.S. Preventive Services Task Force† are
Ned Calonge, MD, MPH, Chair (Colorado Department of Public
Health and Environment, Denver, Colorado); Diana B.
Petitti, MD, MPH, Vice Chair (Keck School of Medicine, University
of Southern California, Sierra Madre, California);
Thomas G. DeWitt, MD (Children's Hospital Medical Center,
Cincinnati, Ohio); Leon Gordis, MD, MPH, DrPH (Johns
Hopkins Bloomberg School of Public Health, Baltimore, Maryland);
Kimberly D. Gregory, MD, MPH (Cedars-Sinai Medical
Center, Los Angeles, California); Russell Harris, MD, MPH
(University of North Carolina School of Medicine, Chapel Hill,
North Carolina); Kenneth W. Kizer, MD, MPH (National
Quality Forum, Washington, DC); Michael L. LeFevre, MD,
MSPH (University of Missouri School of Medicine, Columbia,
Missouri); Carol Loveland-Cherry, PhD, RN (University of
Michigan School of Nursing, Ann Arbor, Michigan); Lucy N.
Marion, PhD, RN (Medical College of Georgia, Augusta, Georgia);
Virginia A. Moyer, MD, MPH (University of Texas Health
Science Center, Houston, Texas); Judith K. Ockene, PhD (University
of Massachusetts Medical School, Worcester, Massachusetts);
George F. Sawaya, MD (University of California, San
Francisco, San Francisco, California); Albert L. Siu, MD, MSPH
(Mount Sinai Medical Center, New York, New York); Steven M.
Teutsch, MD, MPH (Merck & Company, West Point, Pennsylvania);
and Barbara P. Yawn, MD, MSPH, MSc (Olmsted Medical
Center, Rochester, Minnesota).
*Members of the Task Force at the time this recommendation was finalized. For a list of current Task Force members, go to http://www.ahrq.gov/clinic/uspstfab.htm.
Disclaimer: Recommendations made by the USPSTF are independent of
the U.S. government. They should not be construed as an official position
of the Agency for Healthcare Research and Quality or the U.S.
Department of Health and Human Services.
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Copyright Information
Source: U.S. Preventive Services Task Force. Screening for bacterial vaginosis in pregnancy to prevent preterm delivery: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med 2008 148(3):214-19.
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AHRQ Publication No. 08-05106-EF-2
Current as of February 2008
Internet Citation:
U.S. Preventive Services Task Force. Screening for Bacterial Vaginosis in Pregnancy to Prevent Preterm Delivery: U.S. Preventive Services Task Force Recommendation Statement. AHRQ Publication No. 08-05106-EF-2, February 2008. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/clinic/uspstf08/bv/bvrs.htm
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