Bacterial Vaginosis in Pregnancy: Screening -- Asymptomatic pregnant women at low risk for preterm delivery


General

Grade: D The USPSTF recommends against the service. There is moderate or high certainty that the service has no net benefit or that the harms outweigh the benefits. Discourage the use of this service.

Specific Recommendations

The USPSTF recommends against screening for bacterial vaginosis in asymptomatic pregnant women at low risk for preterm delivery.

Frequency of Service

No information available.

Risk Factor Information

No information available.


Clinical

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).

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.


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.


Others

The Centers for Disease Control and Prevention, the American College of Obstetricians and Gynecologists, the Cochrane Pregnancy and Childbirth Group, the British Association for Sexual Health and HIV/Clinical Effectiveness Group, and the American Academy of Family Physicians make similar recommendations about screening and treatment of pregnant women with bacterial vaginosis. 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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