Green Vaginal Discharge: Evaluation and Management
Primary Diagnosis: Trichomoniasis
The most likely cause of daily green mucus vaginal discharge is trichomoniasis, and you should treat empirically with metronidazole 2 g orally as a single dose while awaiting confirmatory testing. 1
Clinical Presentation
- Trichomoniasis characteristically presents with a frothy, greenish-yellow vaginal discharge accompanied by prominent vulvar itching and irritation. 1
- The discharge is typically copious, malodorous (fishy or foul odor), and associated with vaginal pH >4.5. 1, 2
- On speculum examination, look for a "strawberry cervix" (punctate hemorrhagic lesions), which is pathognomonic for trichomoniasis but present in only a minority of cases. 1
- Approximately 50% of infected women may have minimal symptoms, but the presence of daily green discharge makes symptomatic infection highly likely. 1
Diagnostic Workup
Essential Office Tests
- Measure vaginal pH using narrow-range pH paper; pH >4.5 strongly suggests trichomoniasis or bacterial vaginosis, while pH <4.5 suggests candidiasis. 2
- Perform a whiff test by adding 10% KOH to vaginal discharge; a fishy amine odor indicates bacterial vaginosis or trichomoniasis. 2
- Examine a saline wet mount under microscopy for motile flagellated trichomonads, though this detects only 40-80% of infections. 1, 2
- Order nucleic acid amplification testing (NAAT) for Trichomonas vaginalis, as this is the most sensitive diagnostic method and should be obtained even if wet mount is negative. 2
Additional Testing
- Test for Neisseria gonorrhoeae and Chlamydia trachomatis via NAAT, as mucopurulent cervicitis from these pathogens can mimic trichomoniasis with greenish discharge. 1, 2
- Inspect the cervix for mucopurulent discharge, friability, or hyperemia, which suggest cervicitis rather than vaginitis. 1
Treatment Protocol
Primary Therapy
- Administer metronidazole 2 g orally as a single dose to achieve microbiologic cure of Trichomonas vaginalis infection. 1
- Alternative regimen: metronidazole 500 mg orally twice daily for 7 days if single-dose therapy fails or is not tolerated. 1
- Tinidazole is an alternative agent with similar efficacy. 1
Partner Management
- Treat all sexual partners simultaneously with the same metronidazole 2 g single-dose regimen to prevent reinfection. 1
- Advise patients to abstain from sexual intercourse until both the patient and all partners have completed therapy and are asymptomatic. 1
Critical Clinical Implications
- Trichomoniasis increases the risk of HIV acquisition and transmission, making prompt diagnosis and treatment essential. 1
- In pregnant women, trichomoniasis is associated with preterm delivery and premature rupture of membranes; the same 2 g metronidazole regimen is safe during pregnancy. 1
- Persistent symptoms after treatment suggest either reinfection from an untreated partner or metronidazole-resistant T. vaginalis, requiring re-evaluation and possible alternative therapy. 2
Differential Diagnosis Considerations
Bacterial Vaginosis
- Bacterial vaginosis typically presents with thin, homogeneous white-gray discharge rather than green discharge. 1, 2
- BV is non-inflammatory and does not produce the punctate hemorrhagic cervical lesions seen in trichomoniasis. 1
- Clue cells on wet mount and a positive whiff test distinguish BV from trichomoniasis. 2
Cervicitis
- Mucopurulent cervical discharge from gonorrhea or chlamydia can appear greenish and drain into the vagina. 1
- Cervical friability, hyperemia, and easily induced bleeding on speculum examination indicate cervicitis rather than vaginitis. 1, 2
Aerobic Vaginitis
- Aerobic vaginitis can present with yellow-green, thick mucoid discharge and vaginal inflammation. 3
- This condition shows abundant leukocytes and immature epithelial cells on microscopy, distinguishing it from trichomoniasis. 3
Common Pitfalls to Avoid
- Never rely solely on visual appearance of discharge to determine etiology, as clinical characteristics are unreliable for distinguishing causes. 2
- Do not assume a negative wet mount rules out trichomoniasis; NAAT is required for definitive diagnosis due to the low sensitivity of microscopy. 1, 2
- Do not treat based on symptoms alone without performing pH testing, wet mount, and NAAT, as multiple conditions can present similarly. 2
- Do not neglect partner treatment, as failure to treat sexual partners is the most common cause of recurrent trichomoniasis. 1
- Consider the possibility of mixed infections; trichomoniasis can coexist with bacterial vaginosis or candidiasis, requiring combined therapy. 3
When Initial Testing Is Negative
- If wet mount and initial cultures are negative but clinical suspicion remains high, obtain NAAT for T. vaginalis and treat empirically while awaiting results. 2
- Re-examine the wet mount for motile trichomonads, as detection depends heavily on examiner skill and timing of examination. 2
- Consider non-infectious causes such as chemical or allergic irritation if all infectious workup is negative and discharge is minimal. 2