Gestational Age Cutoff for Misoprostol Use
Misoprostol can be safely used up to 7 weeks gestation (49 days) when combined with mifepristone for medication abortion, and up to 12 weeks (84 days) for early pregnancy loss, but requires gestational age-adjusted dosing for second and third trimester use with specific contraindications in women with advanced liver failure. 1, 2
First Trimester Use (Up to 12-13 Weeks)
For medication abortion: Misoprostol combined with mifepristone is effective up to 77 days (11 weeks) gestation, using 800 mcg buccally or vaginally after 200 mg oral mifepristone 2
For early pregnancy loss: The regimen is safe and effective up to 84 days (12 weeks) gestation 2
Mifepristone alone: Can be used up to 7 weeks gestation as an alternative to surgical evacuation in select high-risk populations 1, 3
Misoprostol monotherapy: When mifepristone is unavailable, 400 mcg vaginal misoprostol every 3 hours up to 5 doses can be used between 13-22 weeks 4
Second Trimester Use (13-26 Weeks)
Gestational age-adjusted dosing is critical to minimize complications 5:
13-17 weeks: 200 mcg vaginally every 6 hours 5
18-26 weeks: 100 mcg vaginally every 6 hours 5
13-22 weeks (alternative regimen): 400 mcg vaginally every 3 hours up to 5 doses appears effective without excessive side effects 4
23-26 weeks: Inadequate data exists, but reduced dose and frequency are advisable 4
Third Trimester Use (≥27 Weeks)
After 27 weeks: 25-50 mcg every 4 hours for intrauterine fetal death 5
Labor induction: While no absolute contraindication exists, there is theoretical risk of coronary vasospasm and arrhythmias 1
Critical Contraindications and Special Populations
Absolute Contraindications
Previous cesarean delivery: Misoprostol should be avoided due to increased uterine rupture risk 6, 7, 5
Advanced liver failure: Misoprostol (E1 prostaglandin) requires hepatic metabolism to its active form (E2 prostaglandin), making it less suitable for women with hepatic failure 1
Relative Contraindications
Active cardiovascular disease: Dinoprostone (E2) has more profound blood pressure effects than misoprostol (E1) and is contraindicated in active CVD, though misoprostol carries theoretical risks of coronary vasospasm 1
Cyanotic heart disease: Mechanical methods (Foley catheter) are preferable to avoid drops in systemic vascular resistance 1
Important Clinical Caveats
High-risk patients (cardiac disease, end-stage renal disease) should be managed in experienced centers with emergency support services available 1, 3
Previous cesarean patients require lower doses and dose doubling should not occur 5
Monitoring requirements: Systemic arterial oxygen saturation should be monitored with pulse oximetry when prostaglandin E compounds are used, with norepinephrine infusion available to support diastolic blood pressure 1
Post-procedure monitoring: Clinical monitoring must continue after delivery due to risk of postpartum atony and placenta retention 5
Expected side effects: Gastrointestinal symptoms, fever/rigors, pain, cramping, and bleeding lasting 9-16 days on average are expected 6, 2