What is the likely cause of frothy greenish vaginal discharge and itching, bacterial or fungal infection?

Frothy Greenish Vaginal Discharge with Itching: Likely Trichomoniasis

The frothy greenish discharge with itching is most consistent with trichomoniasis, a protozoal infection caused by Trichomonas vaginalis, not bacterial or fungal infection. 1, 2

Clinical Reasoning

Classic Presentation of Trichomoniasis

• Frothy discharge is pathognomonic for trichomoniasis and is rarely seen with bacterial vaginosis or candidiasis 3, 2, 4
• The yellow-green or greenish color strongly suggests trichomoniasis rather than the white discharge of bacterial vaginosis or the thick white "cottage cheese" discharge of candidiasis 2, 5, 4
• Itching and vulvovaginal irritation are prominent features of trichomoniasis 2, 4
• A foul odor may accompany the discharge in trichomoniasis 3

Distinguishing Features from Other Causes

Bacterial Vaginosis (NOT the likely diagnosis here):

• Produces a homogeneous, thin white discharge—not frothy or green 1
• Characterized primarily by fishy odor rather than prominent itching 1
• Lacks significant vulvar inflammation 1

Vulvovaginal Candidiasis (NOT the likely diagnosis here):

• Presents with thick, white "curdled" or "cottage cheese-like" discharge—not frothy or green 3, 5, 4
• Pruritus is the dominant symptom, but discharge color and consistency are distinctly different 3, 5
• Vaginal pH remains normal (3.8-4.2) unlike the elevated pH (>4.5) expected with trichomoniasis 3, 5

Expected Wet Mount Findings

When the wet mount results return, you should expect:

• Motile trichomonads (flagellated protozoa) visible on saline microscopy, though sensitivity is only 50-75% 3, 5
• Elevated vaginal pH >4.5 (present in 70% of cases) 3
• Punctate cervical microhemorrhages ("strawberry cervix") may be visible on examination in 25% of cases 3
• Increased white blood cells on microscopy 3

Critical Management Points

Treatment Approach:

• Standard treatment is oral metronidazole 2g as a single dose 3, 4
• Alternative: oral tinidazole 5
• Sexual partners MUST be treated simultaneously to prevent reinfection—treatment failure is usually due to untreated partners 3, 5, 4

Important Caveat:

• If wet mount is negative but clinical suspicion remains high based on the frothy green discharge, nucleic acid amplification testing (NAAT) should be performed, as the CDC recommends this for symptomatic or high-risk women given the limited sensitivity of microscopy 5
• Trichomoniasis is a sexually transmitted infection, so screening for other STIs (chlamydia, gonorrhea) should be considered 1, 5