Treatment of Trichomoniasis During Pregnancy
Pregnant women with trichomoniasis should be treated with metronidazole 2 g orally as a single dose, but only after the first trimester is complete. 1, 2
Timing of Treatment Based on Trimester
- Metronidazole is contraindicated during the first trimester due to concerns about fetal organogenesis, as the drug crosses the placental barrier rapidly and its effects on early fetal development are not fully known 1, 2
- If symptomatic trichomoniasis presents during the first trimester, treatment must be delayed until the second trimester begins 1
- Treatment after the first trimester is warranted because trichomoniasis is associated with serious adverse pregnancy outcomes including premature rupture of membranes and preterm delivery 1, 3
Recommended Dosing Regimen in Pregnancy
- The single 2 g dose is specifically recommended for pregnant women rather than the 7-day regimen to minimize total fetal drug exposure 1, 2
- The alternative 7-day regimen (metronidazole 500 mg twice daily for 7 days) should not be used in pregnant patients as it results in higher cumulative serum levels that can reach the fetal circulation 2
- The FDA label explicitly states: "In pregnant patients in whom alternative treatment has been inadequate, the one-day course of therapy should not be used, as it results in higher serum levels which can reach the fetal circulation" 2
Critical Management Points
- All sexual partners must be treated simultaneously with the same metronidazole regimen, regardless of symptoms, as most infected men are asymptomatic 1, 4
- Patients must abstain from sexual intercourse until both partners complete treatment and are asymptomatic to prevent reinfection 1, 4
- Patients must avoid all alcohol during treatment and for at least 24 hours after the last dose to prevent severe disulfiram-like reactions 1
Common Pitfalls to Avoid
- Do not use topical metronidazole gel - it is considerably less efficacious for trichomoniasis than oral preparations and should never be used 5, 4
- Do not fail to treat sexual partners - this is the most common cause of treatment failure and reinfection 1, 4
- Do not treat during the first trimester unless alternative treatment has been inadequate and the benefits clearly outweigh risks 2
Evidence Quality Note
While the most recent high-quality research (2018) demonstrates that 7-day metronidazole dosing is superior to single-dose therapy in non-pregnant women (11% vs 19% treatment failure, p<0.0001) 6, the FDA drug label and CDC guidelines specifically recommend single-dose therapy in pregnancy to minimize fetal drug exposure 1, 2. This represents a deliberate trade-off between optimal efficacy and fetal safety considerations.