Vaginal Discharge: Causes and Treatment
In a reproductive-aged woman with vaginal discharge, you must first perform point-of-care testing (vaginal pH, wet mount microscopy, and KOH preparation) to distinguish between the three most common causes: bacterial vaginosis, vulvovaginal candidiasis, and trichomoniasis—each requiring different treatment approaches. 1, 2
Diagnostic Algorithm
Step 1: Measure Vaginal pH
- pH >4.5 suggests bacterial vaginosis or trichomoniasis 1, 2
- pH ≤4.5 indicates vulvovaginal candidiasis 1, 2
Step 2: Perform Whiff Test
- Add 10% KOH to vaginal discharge 1, 2
- Positive fishy odor confirms bacterial vaginosis or trichomoniasis 1, 2
Step 3: Microscopic Examination
- Saline wet mount: Look for motile trichomonads (trichomoniasis) or clue cells (bacterial vaginosis) 1, 2
- KOH preparation: Identify yeast or pseudohyphae (candidiasis) 1, 2
Common Causes and Treatments
Bacterial Vaginosis
Clinical presentation:
- Homogeneous, thin, white-gray discharge with fishy odor 1
- pH >4.5 with positive whiff test 1
- Clue cells on microscopy 1
Treatment:
- Metronidazole 500 mg orally twice daily for 7 days 3
- Do not treat male partners—this does not prevent recurrence 1
Vulvovaginal Candidiasis
Clinical presentation:
- Thick, white "cottage cheese-like" discharge 3, 2
- Intense pruritus and vulvar erythema 4, 1
- pH <4.5, no odor 1, 3
- Yeast or pseudohyphae on KOH preparation 1, 2
Treatment for uncomplicated cases:
- Short-course topical azoles (80-90% cure rate) 4
- Fluconazole 150 mg orally as single dose (55% cure rate) 2
- Miconazole 1200 mg vaginal insert as single dose 5
Treatment for complicated/recurrent cases (≥4 episodes per year):
- Initial longer course (7-14 days) followed by maintenance therapy for 6 months 1
- Fluconazole 150 mg weekly for 6 months 1
- Partner treatment may be considered only in women with recurrent infection 4
Trichomoniasis
Clinical presentation:
- Yellow-green discharge with malodor 1, 2
- Vulvar irritation and pruritus 2
- Motile trichomonads on wet mount 2
Treatment:
- Metronidazole 2 grams orally as single dose (90-95% cure rate) 2
- Treat sexual partners simultaneously to prevent reinfection 6
Special Population Considerations
Pregnant Women
- Use only 7-day topical azole therapies for candidiasis—oral fluconazole is contraindicated 4, 1
- Follow-up evaluation one month after treatment to verify cure 2
- Suspected pelvic inflammatory disease requires hospitalization and parenteral antibiotics 4
HIV-Infected Women
Critical Pitfalls to Avoid
- Do not treat without proper diagnosis—pH measurement and microscopy are essential before initiating therapy 1
- Do not treat asymptomatic Candida colonization (present in 10-20% of women) 1
- Avoid self-medication except for women previously diagnosed with candidiasis experiencing identical symptoms 1
- Do not use tampons during treatment—they may remove medication from the vagina 5
- Avoid vaginal douching—it disrupts normal flora and increases infection risk 1
- Do not assume sexual transmission—bacterial vaginosis and candidiasis are not sexually transmitted diseases 3
When to Refer or Escalate Care
Immediate physician evaluation required if:
- First episode of vaginal discharge ever 5
- Fever, chills, lower abdominal, back or shoulder pain, or foul-smelling discharge (suggests pelvic inflammatory disease or sexually transmitted infection) 4, 5
- Multiple sex partners or new sex partner (rule out sexually transmitted infections) 5
- Symptoms persist despite treatment within 72 hours 4
- Recurrent infections (≥4 episodes per year) requiring evaluation for diabetes, immunosuppression, or HIV 4, 5