What are the causes of leukorrhea?

Causes of Leukorrhea

Leukorrhea is most commonly caused by bacterial vaginosis (40-50% of cases), followed by vulvovaginal candidiasis (20-25%), and trichomoniasis (10-15%), with cervical infections from Chlamydia trachomatis or Neisseria gonorrhoeae accounting for another 10-15% of cases. 1, 2, 3

Infectious Causes

Most Common Pathogens

• Bacterial vaginosis represents the single most prevalent cause of vaginal discharge and accounts for 40-50% of all leukorrhea cases 2, 3
• Vulvovaginal candidiasis (typically Candida albicans) causes 20-25% of cases presenting with vaginal discharge 1, 3
• Trichomoniasis (Trichomonas vaginalis) is identified in approximately 9-15% of women with leukorrhea 1, 3
• Cervical infections with Chlamydia trachomatis (15%) or Neisseria gonorrhoeae (1-2%) can present as vaginal discharge, though these more commonly cause cervicitis 1, 3

Mixed Infections

• Approximately 14-16% of women with bacterial vaginosis or candidiasis harbor concurrent sexually transmitted organisms 3
• Multiple pathogens can coexist, with some patients harboring more than one sexually transmitted organism simultaneously 3

Non-Infectious Causes

Physiologic and Mechanical Causes

• Physiologic discharge is normal and requires no treatment; this represents a substantial proportion of cases where no pathogen is identified 2, 4
• Intrauterine device-associated discharge can cause leukorrhea without infection 3
• Chemical or mechanical irritation from douching, perfumed products, or other irritants can produce discharge 1, 4
• Cytolytic vaginosis is an uncommon cause identified in approximately 5% of cases where no specific pathogen is found 3

Other Considerations

• Psychological factors may contribute to perceived abnormal discharge in some patients 3
• Urinary tract infections can occasionally present with symptoms mimicking vaginal discharge 3
• Laboratory testing fails to identify a specific cause in approximately 25% of women presenting with leukorrhea 1, 3

Diagnostic Approach to Determine Etiology

Initial Office-Based Testing

• Vaginal pH measurement using narrow-range pH paper: pH ≤4.5 suggests candidiasis, while pH >4.5 indicates bacterial vaginosis or trichomoniasis 1, 2, 4
• Saline wet mount microscopy to identify clue cells (bacterial vaginosis) or motile trichomonads (trichomoniasis) 1, 2, 4
• KOH preparation to perform the whiff test (fishy odor indicates bacterial vaginosis) and identify yeast or pseudohyphae (candidiasis) 1, 2, 4
• Microscopic examination for leukorrhea (>10 white blood cells per high-power field) can indicate cervical inflammation even without vaginitis 4, 5

When to Test for Cervical Infections

• If leukorrhea is present on microscopy (>10 WBCs per high-power field), nucleic acid amplification testing (NAAT) for Chlamydia trachomatis and Neisseria gonorrhoeae should be performed, as leukorrhea strongly predicts cervical infection 4, 5
• Women at high risk (age <25 years, multiple partners, inconsistent condom use, previous STIs) warrant screening even without obvious cervicitis 1

Critical Clinical Pitfalls

Diagnostic Errors to Avoid

• Do not assume negative initial testing rules out bacterial vaginosis, as standard clinical testing misses 20-30% of cases; Gram stain has 90% sensitivity and should be used when symptoms persist 2
• Do not rely solely on symptoms, as up to 50% of women meeting diagnostic criteria for bacterial vaginosis are asymptomatic 1, 2, 4
• Avoid empiric antimicrobial therapy when testing fails to identify a cause, as this leads to inappropriate antibiotic use and more frequent return visits 2, 4

Management Considerations

• Leukorrhea in the presence or absence of bacterial vaginosis is strongly associated with cervical infections (relative risk 15.7-58.7), particularly in high-risk populations 5
• In settings where patient follow-up is uncertain, on-site screening with wet mount identifying leukorrhea may justify empiric antibiotic therapy for sexually transmitted diseases 5
• Partner treatment is not indicated for bacterial vaginosis or candidiasis, but is essential for trichomoniasis, chlamydia, and gonorrhea 1, 4, 6