Treatment of Trichomoniasis in Pregnancy
Pregnant women with trichomoniasis should be treated with metronidazole 2 g orally as a single dose after the first trimester, as this effectively treats the infection and may reduce adverse pregnancy outcomes including preterm delivery and premature rupture of membranes. 1, 2
Timing and Safety Considerations
- Metronidazole is contraindicated during the first trimester of pregnancy due to concerns about fetal organogenesis, though animal studies have shown no evidence of teratogenicity at therapeutic doses 1, 3
- After the first trimester, metronidazole can be safely administered as it is classified as Pregnancy Category B by the FDA 3
- For patients in the second and third trimesters, including those in active labor, metronidazole 2 g orally as a single dose is the recommended regimen 1, 2
Recommended Treatment Regimen
Primary regimen:
Alternative regimen:
- Metronidazole 500 mg orally twice daily for 7 days may be used, though the single-dose regimen is preferred for simplicity and adherence 4
Clinical Rationale for Treatment
- Trichomoniasis is associated with significant adverse pregnancy outcomes, including premature rupture of membranes, preterm labor, and preterm delivery 4, 2
- Treatment is warranted even in asymptomatic pregnant women to prevent these complications 2, 5
- Cure rates with oral metronidazole approach 90-95% in clinical trials 4
Important Clinical Caveats
Topical Therapy is Ineffective
- Intravaginal metronidazole gel should NOT be used for trichomoniasis treatment, as it achieves inadequate therapeutic levels in the urethra and perivaginal glands 4
- Studies demonstrate that intravaginal metronidazole has only 50% cure rates compared to 88% with oral therapy 6, 7
Partner Treatment is Essential
- All sexual partners must be treated simultaneously to prevent reinfection, even without screening 1, 2, 5
- Patients should abstain from sexual intercourse until both partners complete treatment and are asymptomatic 1
First Trimester Management
- For first trimester patients, treatment should be carefully evaluated and potentially deferred until the second trimester unless symptoms are severe 4, 3
- Alternative treatments are not effective—topical agents have poor cure rates and should not be relied upon 6, 7
Follow-Up Recommendations
- Routine test-of-cure is unnecessary for patients who become asymptomatic after treatment 4, 1, 5
- If treatment fails, re-treat with metronidazole 500 mg twice daily for 7 days 1, 2
- For repeated treatment failures, consider metronidazole 2 g once daily for 3-5 days 4, 1
Special Considerations
HIV-Infected Pregnant Women
Metronidazole Allergy
- Patients with true metronidazole allergy present a significant challenge, as no effective alternatives exist 1
- Desensitization may be required for patients with immediate-type hypersensitivity reactions 1
- One case report documented successful pregnancy outcome at 34 weeks without treatment in an allergic patient, though this is not recommended practice 8
Evidence Quality Note
While older CDC guidelines from 1998 recommended the single-dose regimen 4, more recent evidence from 2018 suggests that 7-day dosing may be superior in non-pregnant populations (11% vs 19% treatment failure) 9. However, current guidelines for pregnancy still favor the single 2 g dose for simplicity and adherence 1, 2, and both regimens remain acceptable alternatives 5.