Bacterial vaginosis

Abstract

Bacterial vaginosis is the most common cause of vaginitis, affecting over 3 million women in the United States annually. Depopulation of lactobacilli from the normal vaginal flora and overgrowth of Gardnerella vaginalis and other anaerobic species are the presumed etiology. To date, no scientific evidence shows that bacterial vaginosis is a sexually transmitted disease. Malodorous vaginal discharge is the most common symptom. Differential diagnoses include trichomoniasis, moniliasis, and allergic or chemical dermatitis. The diagnosis is confirmed when at least three of the following four findings are present (Amsel’s criteria): 1) thin, homogenous discharge, 2) pH greater than 4.5, 3) positive amine test, and 4) presence of clue cells. The sensitivity and positive predictive value are both 90%. Vaginal Gram stain is also reliable and allows for permanent record. Cultures are nonspecific because G. vaginalis resides in normal vaginal flora as well. Papanicolaou smears are not particularly sensitive, but their positive predictive value is very high. The Centers for Disease Control and Prevention recommend three treatment regimens in nonpregnant patients: oral metronidazole (500 mg twice daily for 7 days), intravaginal 2% clindamycin cream (one applicatorful at bedtime for 7 days), or intravaginal metronidazole gel (one to two applicatorfuls per day for 5 days). Alternative regimens include a single 2-g oral dose of metronidazole or a 7-day course of oral clindamycin, 300 mg twice daily. The association between bacterial vaginosis and adverse pregnancy outcomes has satisfied many criteria for a causal inference. Treatment of bacterial vaginosis in women with previous history of preterm labor results in fewer preterm deliveries than in untreated women from the same population.