Vaginitis for USMLE Step 2
Start your One-Week Free Trial
Already subscribed? Log in »
Vaginitis for the USMLE Step 2 Exam
Definition and Classification
- Definition
- Vaginitis is an inflammation of the vaginal mucosa, commonly presenting with discharge, pruritus, odor, and/or irritation.
- Major causes include:
- Bacterial Vaginosis (BV): Overgrowth of anaerobic bacteria in the vagina.
- Vulvovaginal Candidiasis (VVC): Fungal infection, primarily by Candida albicans.
- Trichomoniasis: Sexually transmitted infection caused by Trichomonas vaginalis.
- Epidemiology
- Vaginitis is one of the most common gynecologic complaints, with BV and VVC prevalent in reproductive-age women, while trichomoniasis is the most common non-viral STI worldwide.
Pathophysiology
- Bacterial Vaginosis (BV):
- Results from a decrease in lactobacilli, which usually produce lactic acid to maintain a low vaginal pH.
- A shift in vaginal flora promotes overgrowth of anaerobic bacteria like Gardnerella vaginalis, Mycoplasma, Mobiluncus, and Prevotella.
- BV is associated with sexual activity but is not considered an STI.
- Vulvovaginal Candidiasis (VVC):
- Overgrowth of Candida species, primarily C. albicans, due to an imbalance in vaginal flora.
- Risk factors include antibiotic use, diabetes, immunosuppression, and elevated estrogen levels (e.g., pregnancy, oral contraceptives).
- Trichomoniasis:
- Caused by Trichomonas vaginalis, a flagellated protozoan transmitted through sexual contact.
- Reinfection is common if sexual partners are not treated, and infection may be asymptomatic in many cases.
Clinical Manifestations
- Bacterial Vaginosis (BV):
- Thin, homogeneous gray-white discharge with a “fishy” odor, especially noticeable after intercourse.
- May include mild irritation or itching, but symptoms are often mild or absent.
- Vulvovaginal Candidiasis (VVC):
- Thick, white, “cottage cheese” discharge, generally odorless.
- Associated with intense pruritus, erythema, vulvar swelling, and sometimes dysuria or dyspareunia.
- Trichomoniasis:
- Frothy, yellow-green discharge with a foul odor.
- Often presents with vaginal itching, erythema, and occasionally “strawberry cervix” (cervical petechiae).
Diagnosis
- Microscopy (Wet Mount):
- BV: Presence of clue cells (epithelial cells covered with bacteria) and a positive “whiff test” (fishy odor with KOH application).
- VVC: Budding yeast and pseudohyphae visible with KOH preparation.
- Trichomoniasis: Motile, flagellated trichomonads observed in a saline wet mount.
- pH Testing:
- BV and Trichomoniasis: Vaginal pH is typically >4.5.
- VVC: Vaginal pH remains normal (≤4.5).
- Nucleic Acid Amplification Tests (NAATs):
- Highly sensitive for detecting Trichomonas vaginalis.
- Affirm VPIII test is also 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 for 5 days.
- Clindamycin 2% cream intravaginally for 7 days.
- Recurrent BV: Maintenance therapy with metronidazole gel twice weekly for 4-6 months may reduce recurrences.
- Vulvovaginal Candidiasis (VVC):
- Uncomplicated VVC: Treated with topical azoles (e.g., clotrimazole, miconazole) for 1-7 days or oral fluconazole 150 mg single dose.
- Complicated VVC: Extended therapy with topical azoles for 7-14 days or fluconazole 150 mg orally every 3 days for 3 doses.
- Recurrent VVC: Defined as four or more episodes per year; requires induction therapy with fluconazole, followed by weekly fluconazole 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: Essential to prevent reinfection.
- Test of Cure: Recommended at 3 months due to high reinfection rates in women.
Key Points
- Vaginitis is commonly caused by BV, VVC, and trichomoniasis, each with distinct symptoms and management.
- Symptoms:
- BV: Thin, gray-white discharge with a fishy odor; pH >4.5.
- VVC: Thick, white “cottage cheese” discharge with intense pruritus; pH ≤4.5.
- Trichomoniasis: Frothy, yellow-green discharge with foul odor; pH >4.5.
- Diagnosis:
- Wet mount microscopy, pH testing, and NAATs are essential diagnostic tools.
- Treatment:
- BV: Metronidazole or clindamycin.
- VVC: Topical azoles or fluconazole for uncomplicated cases; prolonged therapy for complicated or recurrent cases.
- Trichomoniasis: Metronidazole with partner treatment to avoid reinfection.
- Complications:
- BV and trichomoniasis increase the risk for pelvic inflammatory disease (PID), preterm birth, and susceptibility to other STIs.