Recommended Regimen for Medical Abortion at 15 Days Post-Coitus
At approximately 15 days after intercourse (roughly 4 weeks gestational age), the most effective regimen is mifepristone 200 mg orally followed 24-48 hours later by misoprostol 800 mcg administered vaginally or buccally 1.
Critical First Step: Confirm Intrauterine Pregnancy
Before initiating any abortion regimen, you must:
- Confirm intrauterine pregnancy location to rule out ectopic pregnancy
- Use ultrasound if gestational dating cannot be confirmed clinically or if ectopic risk factors exist 1
- At 15 days post-coitus, ultrasound may not yet visualize a gestational sac, so clinical judgment and beta-hCG levels may be needed
Optimal Medication Protocol
Primary Regimen (Most Effective)
Mifepristone-Misoprostol Combination:
- Day 1: Mifepristone 200 mg orally 1, 2
- Day 2-3 (24-48 hours later): Misoprostol 800 mcg vaginally or buccally 1
- This achieves >95% complete abortion rates at this early gestational age 3
Key Evidence: The 200 mg dose of mifepristone is equally effective as 600 mg when combined with misoprostol 2. The combination regimen dramatically outperforms misoprostol-only, with ongoing pregnancy rates of only 4% at 24 hours versus 32% with misoprostol alone 2.
Alternative if Mifepristone Unavailable
Misoprostol-Only Regimen:
- Misoprostol 800 mcg vaginally, repeated every 3-6 hours as needed
- Less effective than combination therapy (10% ongoing pregnancy at 48 hours vs 2%) 2
- Higher doses (400-600 mcg) are more effective than lower doses 2
Expected Course and Management
What to Expect
- Bleeding duration: Average 9-16 days 1
- Cramping and bleeding are expected effects, not complications
- Most patients complete abortion within 24-48 hours of misoprostol administration 2
Managing Side Effects
- Pain: NSAIDs for cramping (expected and normal)
- Misoprostol side effects: Low-grade fever, nausea, diarrhea—manage with NSAIDs or antiemetics 1
- These are medication effects, not complications
Follow-Up Confirmation
Confirm complete abortion using one of:
- Serial quantitative beta-hCG levels (should decline appropriately)
- Urine pregnancy testing at 2-4 weeks
- Ultrasound if clinical uncertainty 1
Critical Safety Considerations
Rare but Serious Complications (<5%):
- Ongoing pregnancy (requires repeat treatment or aspiration)
- Hemorrhage requiring intervention
- Infection
- Undiagnosed ectopic pregnancy 1
When to Seek Immediate Care:
- Soaking through 2+ pads per hour for 2+ consecutive hours
- Severe abdominal pain not relieved by NSAIDs
- Fever >38°C lasting >24 hours
- Signs of hemodynamic instability
Common Pitfalls to Avoid
Don't use concurrent administration: A 2025 RCT showed concurrent mifepristone-misoprostol has significantly lower success (68.8% vs 84.3%) and higher continuing pregnancy rates (13.4% vs 2.8%) compared to the 48-hour interval 4. The interval protocol is essential.
Don't assume ultrasound is always necessary: At this early gestational age, clinical dating may suffice unless ectopic risk factors exist 1
Don't stop misoprostol prematurely: If additional doses are needed, there's no safety rationale to stop after 5 doses—continue until expulsion occurs 2
Don't confuse gestational age with post-coital timing: 15 days post-coitus equals approximately 4 weeks gestational age (counting from last menstrual period), well within the early first-trimester window where this regimen is most effective
This regimen is appropriate for pregnancies up to 70 days (10 weeks) gestational age, making it highly suitable for your patient at approximately 4 weeks gestation 1.