Vaginitis for USMLE Step 3
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Vaginitis for the USMLE Step 3 Exam
Definition and Classification
- Definition
- Vaginitis is an inflammation or infection of the vaginal mucosa, typically resulting in symptoms such as discharge, pruritus, irritation, and/or malodor.
- The three primary causes are:
- Bacterial Vaginosis (BV): Overgrowth of anaerobic bacteria, commonly without inflammation.
- Vulvovaginal Candidiasis (VVC): Fungal infection, primarily due to Candida albicans.
- Trichomoniasis: Sexually transmitted infection caused by the protozoan Trichomonas vaginalis.
- Epidemiology
- Vaginitis is one of the most frequent gynecologic complaints, with BV and VVC common in reproductive-age women. Trichomoniasis is the most prevalent non-viral STI worldwide.
Pathophysiology
- Bacterial Vaginosis (BV):
- BV results from an imbalance in the vaginal flora, particularly a decrease in lactobacilli which maintain low pH by producing lactic acid.
- Anaerobic bacteria like Gardnerella vaginalis, Mobiluncus, Prevotella, and Mycoplasma species overgrow, leading to characteristic discharge and odor.
- BV is linked to sexual activity but is not classified as an STI.
- Vulvovaginal Candidiasis (VVC):
- Overgrowth of Candida species (usually C. albicans), a part of normal vaginal flora, due to a shift in the vaginal environment.
- Risk factors include recent antibiotic use, diabetes, pregnancy, immunosuppression, and estrogen therapy.
- Trichomoniasis:
- Caused by Trichomonas vaginalis, a motile protozoan transmitted sexually.
- Reinfection is common if sexual partners remain untreated.
Clinical Manifestations
- Bacterial Vaginosis (BV):
- Thin, homogeneous, gray-white discharge with a distinct “fishy” odor, often more prominent after intercourse.
- Symptoms may be mild, with some patients experiencing only mild irritation or no symptoms at all.
- Vulvovaginal Candidiasis (VVC):
- Thick, white, “cottage cheese”-like discharge without a strong odor.
- Often associated with intense vulvar itching, erythema, swelling, and sometimes dysuria or dyspareunia.
- Trichomoniasis:
- Frothy, yellow-green discharge with a foul odor.
- Accompanied by vaginal pruritus, burning, and erythema. Examination may reveal a “strawberry cervix” with punctate hemorrhages.
Diagnosis
- Microscopy (Wet Mount):
- BV: Presence of clue cells (vaginal epithelial cells coated with bacteria) and a positive “whiff” test (fishy odor on KOH application).
- VVC: Pseudohyphae and budding yeast observed on KOH preparation.
- Trichomoniasis: Motile, flagellated trichomonads visible in a saline wet mount.
- pH Testing:
- BV and Trichomoniasis: Vaginal pH >4.5.
- VVC: Vaginal pH typically ≤4.5.
- Nucleic Acid Amplification Tests (NAATs):
- High sensitivity for detecting Trichomonas vaginalis; often used in settings where wet mount microscopy is unavailable.
- Affirm VPIII test is available to detect Gardnerella, Candida, and Trichomonas.
Management
- Bacterial Vaginosis (BV):
- First-Line Therapy:
- Metronidazole 500 mg orally twice daily for 7 days or metronidazole gel 0.75% intravaginally once daily for 5 days.
- Clindamycin cream 2% intravaginally once daily for 7 days.
- Recurrent BV: Metronidazole gel twice weekly for 4-6 months to prevent recurrence.
- Vulvovaginal Candidiasis (VVC):
- Uncomplicated VVC: Treated with topical azoles (e.g., clotrimazole, miconazole) or a single dose of oral fluconazole 150 mg.
- Complicated VVC: For severe symptoms, recurrent cases, or immunocompromised patients, treat with topical azoles for 7-14 days or fluconazole 150 mg every 3 days for 3 doses.
- Recurrent VVC: Defined as four or more episodes per year; managed with induction therapy using fluconazole, followed by weekly maintenance for 6 months.
- Trichomoniasis:
- First-Line Therapy: Metronidazole 2 g orally in a single dose or 500 mg twice daily for 7 days.
- Partner Treatment: Necessary to prevent reinfection.
- Test of Cure: Recommended in 3 months for women due to high reinfection rates.
Key Points
- Vaginitis is commonly due to BV, VVC, or trichomoniasis, each with distinct presentations and management.
- Symptoms:
- BV: Thin, gray-white discharge with fishy odor; pH >4.5.
- VVC: Thick, white “cottage cheese” discharge with pruritus; pH ≤4.5.
- Trichomoniasis: Frothy, yellow-green discharge with foul odor; pH >4.5.
- Diagnosis:
- Microscopy, pH testing, and NAATs are essential diagnostic tools.
- Treatment:
- BV: Metronidazole or clindamycin.
- VVC: Topical azoles or fluconazole; extended therapy for recurrent cases.
- Trichomoniasis: Single-dose metronidazole and partner treatment to prevent reinfection.
- Complications:
- BV and trichomoniasis increase risks for PID, preterm birth, and susceptibility to other STIs.