Medication Abortion Regimen
The recommended regimen for medication abortion is mifepristone 200 mg orally followed by misoprostol 800 mcg administered buccally or vaginally 24-48 hours later, which is safe and effective through 63 days (9 weeks) of gestation. 1, 2, 3
Standard Dosing Protocol
Mifepristone Administration
- Dose: 200 mg taken orally as a single dose 1, 2, 3
- Mechanism: Acts as a progesterone receptor antagonist to prepare the uterus for expulsion 1
Misoprostol Administration
- Dose: 800 mcg administered 24-48 hours after mifepristone 1, 2, 3
- Route options: Buccal (preferred) or vaginal administration 1, 2
- Location: Can be self-administered at home 3
Efficacy by Gestational Age
The regimen demonstrates high efficacy with declining success rates at later gestational ages:
- Overall efficacy through 63 days: 96.7-97.7% 2, 3
- 29-42 days gestation: 98.8% success rate 3
- 43-49 days gestation: Remains highly effective 2
- 50-56 days gestation: Slightly decreased efficacy 2
- 57-63 days gestation: 95.5% success rate 3
- 64-70 days gestation: 93.1% efficacy (limited data with only 332 cases reported) 2
- Continuing pregnancy rate: 0.8% through 63 days 2
Alternative Timing Considerations
Simultaneous administration is an option but slightly less effective: Mifepristone and misoprostol can be given simultaneously (misoprostol immediately after mifepristone in the office), with a complete abortion rate of 95.1%, which is statistically noninferior to the 24-hour interval regimen (96.9%) 4. However, the 24-48 hour interval appears slightly more effective than immediate or 24-hour-only intervals based on current evidence 2.
Expected Effects and Side Effect Management
Normal Expected Effects
- Cramping and bleeding: These are expected therapeutic effects, not complications 1
- Duration of bleeding: Average 9-16 days 1
Common Side Effects from Misoprostol
- Low-grade fever 1
- Gastrointestinal symptoms (nausea, diarrhea, vomiting) 1, 4
- Warmth or chills (more common with simultaneous administration) 4
Management
Rare Complications
The following complications occur infrequently but require monitoring:
- Ongoing pregnancy: 0.8% 2
- Unplanned surgical aspiration needed: 1.8-4.2% for reasons other than ongoing pregnancy 2
- Blood transfusion: 0.03-0.6% 2
- Hospitalization: 0.04-0.9% 2
- Infection requiring hospitalization: 0.01% 3
- Hemorrhage: Rare 1
- Undiagnosed ectopic pregnancy: Rare 1
Follow-Up and Confirmation of Complete Abortion
Establish treatment completion using one of the following methods:
- Clinical history combined with serial quantitative beta-hCG levels 1
- Urine pregnancy testing 1
- Transvaginal ultrasonography (typically performed 7±1 days after treatment initiation) 1, 4
- Follow-up contact approximately 5 weeks after treatment 4
Second Trimester Protocol (12-20 Weeks)
For gestations between 12-20 weeks, a modified regimen is used:
- Mifepristone: 200 mg orally 5
- Initial misoprostol: 800 mcg vaginally 36-48 hours after mifepristone 5
- Repeat dosing: 400 mcg vaginally every 3 hours (maximum 4 doses in 24 hours) 5
- Efficacy: 97.9% abort within 24 hours, 99.5% within 36 hours 5
- Median induction-to-abortion interval: 6.7 hours (longer in nulliparous women at 7.6 hours vs 6.0 hours in multiparous) 5
Important Clinical Caveats
Gestational Age Determination
- Use ultrasonography or menstrual history to determine gestational age 1
- Ultrasonography is required when gestational dating cannot be confirmed clinically or when risk factors for ectopic pregnancy exist 1
Setting of Care
- Medication abortion can be performed safely in the outpatient setting with home administration of misoprostol 1, 3
- For high-risk patients requiring termination (such as those with cardiovascular disease), procedures should be performed in hospital rather than outpatient facilities to ensure emergency support services are available 6