Summary
Bacterial vaginosis, trichomonas vaginitis, Candida vaginitis, and physiologic discharge are the main causes of vaginal discharge. Bacterial vaginosis (most common) results from vaginal flora imbalance, often asymptomatic, with fishy odor, thin gray-white discharge, and clue cells; treated with metronidazole or clindamycin. Trichomonas (sexually transmitted protozoan) causes frothy yellow-green malodorous discharge, vulvar irritation, and strawberry cervix; treated with oral metronidazole for both partners. Candida (fungal overgrowth) presents with intense itching, burning, and thick white “cottage cheese” discharge; treated with oral or topical azoles. Physiologic discharge is thin, watery, non-inflammatory, with normal pH, requiring reassurance or hormonal regulation.
Bacterial Vaginosis:
Prevalence:
Most common cause of vaginal complaints in the U.S. (~50% of cases; 40% of vaginal infections in adult women).
Etiology:
Not a true infection but an imbalance in vaginal flora. Normal lactobacilli are replaced by anaerobes and facultative aerobes (commonly Gardnerella vaginalis, 70–90%).
Transmission:
Not an STD, but associated with sexual activity (early onset, multiple partners, semen reducing acidity). Other risks: vaginal douching, IUD use.
Pathophysiology:
Vaginosis (no inflammation) vs. vaginitis.
Symptoms:
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50% asymptomatic.
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Fishy odor (especially post-intercourse).
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Thin, white or gray discharge.
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No itching, burning, dyspareunia, or vulvar soreness.
Examination:
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Vaginal pH > 4.5 (normal 3.5–4.5).
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Thin, grayish-white discharge.
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No inflammation.
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Positive “whiff test” (fishy odor after adding KOH).
Microscopy:
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Clue cells: vaginal epithelial cells with obscured borders due to adherent bacteria.
Diagnosis:
Requires ≥3 of 4 Amsel’s criteria:
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Thin, white/gray discharge.
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Vaginal pH > 4.5.
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Positive whiff test.
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Presence of clue cells.
Complications:
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2nd-trimester abortion.
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Preterm labor.
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Postpartum endometritis.
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Pelvic inflammatory disease.
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Urinary tract infection.
Management:
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Metronidazole or clindamycin (oral or intravaginal).
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Safe in pregnancy (including 1st trimester).
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No need to treat male partner.
Trichomonas Vaginitis:
Prevalence:
Most common non-viral STD worldwide; third most common cause of vaginal discharge after bacterial vaginosis (≈20%).
Cause:
Trichomonas vaginalis, a flagellated, pear-shaped protozoan; optimal growth at pH 5.5–6.5.
Transmission:
Primarily sexual; may also occur via contaminated towels, rectal sources, or from asymptomatic carriers (men may harbor organism in urethra, seminal vesicles, or prostate).
Clinical Features
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Excessive, yellow-green, frothy, malodorous vaginal discharge.
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Vulvar irritation, pruritus, dysuria, dyspareunia.
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Often associated with burning sensation.
Examination Findings
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Frothy, green discharge; edematous and inflamed vaginal mucosa.
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“Strawberry cervix” (punctate hemorrhages).
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Vaginal pH >4.5.
Diagnosis
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Wet mount: Motile, flagellated trichomonads; increased WBCs.
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Gram stain: Gram-negative organism.
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Culture: Kupferberg or Feinberg medium (if confirmation needed).
Management
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First-line: Oral metronidazole (2 g single dose or 500 mg TID × 7 days).
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Tinidazole: Single-dose alternative.
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Treat both patient and sexual partner simultaneously.
Candida (Yeast) Vaginitis:
Epidemiology:
Second most common vaginal infection in the U.S., typically caused by Candida albicans. Not sexually transmitted.
Risk Factors:
Pregnancy, diabetes mellitus, broad-spectrum antibiotics, oral contraceptives, obesity, immunosuppression, hot climate, and tight clothing.
Symptoms:
Intense vulvar itching, burning, dyspareunia, dysuria; thick, white, odorless vaginal discharge (“cottage cheese” appearance).
Exam Findings:
Erythematous and edematous vaginal mucosa; discharge adherent to walls; vaginal pH normal (<4.5).
Diagnosis:
KOH prep showing pseudohyphae; gram-positive filaments; culture on Nickerson medium.
Treatment:
Single-dose oral fluconazole or topical azole antifungals (miconazole, clotrimazole, itraconazole); no treatment needed for asymptomatic partners. Preventive measures include breathable cotton underwear and avoiding nylon
Physiologic Discharge
Cause:
Thin, watery cervical mucus due to estrogen dominance; normal but may be symptomatic in prolonged anovulation, especially with wide ectropion.
Risk Factors:
Chronic anovulation (e.g., PCOS).
Symptoms:
Increased watery vaginal discharge; no itching or burning.
Exam Findings:
Thin, watery discharge; normal vaginal mucosa without inflammation; vaginal pH <4.5.
Diagnosis:
Wet mount negative for WBCs, clue cells, trichomonads, or pseudohyphae.
Treatment:
Progestin-containing hormonal contraception to thicken mucus.
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