Second Trimester Medication Abortion Regimens and the Mifepristone-Misoprostol Dosing Interval
The purpose of this article is to review current methods of induction termination of pregnancy in the second trimester. The specific area of focus is recent publication regarding timing of mifepristone and misoprostol dosing.
Current Guidelines and Clinical Standards
Current international guidelines recommend initial treatment with mifepristone followed by misoprostol after 24 to 48 h. These standards are addressed in clinical guidance such as the Abortion care guideline by the World Health Organization (WHO) and The Care of Women Requesting Induced Abortion by the Royal College of Obstetricians & Gynaecologists (RCOG).
Recent Findings on Dosing Intervals
Recent Findings indicate that a shorter interval between mifepristone and misoprostol of less than 12 h or even concomitant administration may result in a shorter total abortion time without increasing risk of incomplete abortion or complications. Retrospective studies indicate that these variations in timing can be highly effective.
Summary: Given the potential benefit of increased efficacy, with successful expulsion of the pregnancy, and reduced time to delivery with shorter mifepristone-misoprostol intervals or concurrent administration practitioners should offer all second trimester medication abortion treatment with mifepristone.
Comparison of Observed Regimens
- Standard Regimen: Dosing interval between mifepristone and misoprostol of 24 to 48 hours.
- Shortened Interval: Dosing interval of less than 12 hours.
- Concurrent Administration: Concomitant administration of mifepristone and misoprostol.
Future Evaluation and Research
Further studies are needed to evaluate the implementation of concurrent or varied dosing intervals and the magnitude of benefit vs risks, with attention to the patient experience, resources, and costs.