Misoprostol Dosing Recommendations
For labor induction, use 25 µg vaginal misoprostol every 3-6 hours or 20-25 µg oral solution every 2-6 hours, with the oral route resulting in fewer cesarean sections and lower hyperstimulation rates. 1
Labor Induction and Cervical Ripening
Preferred Dosing Regimens
Vaginal administration: 25 µg every 3-6 hours is effective for cervical ripening and labor induction, with the 4-hourly interval potentially more effective than 6-hourly dosing 2, 3
Oral administration: 20-25 µg every 2-6 hours is the preferred starting dose, resulting in fewer cesarean sections and lower rates of uterine hyperstimulation compared to vaginal administration 1
The 50 µg dose every 6 hours may be appropriate in select situations but carries significantly increased risk of uterine hyperstimulation and should be used cautiously 2
Route Comparison
Oral misoprostol probably results in fewer cesarean sections (RR 0.84) and less hyperstimulation with fetal heart rate changes (RR 0.69) compared to vaginal dinoprostone 1
Vaginal misoprostol achieves more vaginal deliveries within 24 hours (RR 0.82) but may increase uterine hyperstimulation risk 3
Oxytocin augmentation is more frequently needed with oral versus vaginal administration (RR 1.29) 1, 3
Critical Safety Monitoring
Continuous fetal heart rate and uterine activity monitoring is mandatory from 30 minutes to 2 hours after administration 2, 4
Monitor for uterine hyperstimulation, which occurs more frequently with 50 µg doses (35.86% vs 10.75% with 25 µg) 5
Absolute Contraindications
Previous Cesarean Delivery
Misoprostol is absolutely contraindicated in women with previous cesarean delivery due to catastrophic uterine rupture risk 2, 1, 6
Uterine rupture risk with misoprostol is 13%, compared to 1.1% with oxytocin and 2% with prostaglandin E2 1, 6
This contraindication extends to any prior uterine incision, which should be treated equivalently to cesarean delivery 6
Safe alternatives include transcervical Foley catheter (no reported rupture risk), oxytocin (1.1% rupture risk), or dinoprostone (2% rupture risk) 6
Postpartum Hemorrhage
Emergency Dosing
Rectal administration: 1000 µg (five 200 µg tablets) for postpartum hemorrhage unresponsive to oxytocin and ergometrine 7
Sustained uterine contraction typically achieved within 3 minutes of rectal administration 7
This represents an effective alternative to parenteral prostaglandins while awaiting carboprost 7
The FDA label specifies this is for hospital use only and outside the approved indication 8
Intrauterine Fetal Demise
Second Trimester
- High-dose vaginal suppositories may be used for second-trimester intrauterine fetal demise 2
Third Trimester
- Intravaginal misoprostol can be used for labor induction with third-trimester intrauterine fetal demise 2
IUD Placement (Cervical Priming)
Limited Indication
Misoprostol should NOT be used routinely for IUD placement due to limited efficacy and side effects 2
Consider only for failed previous placement or known cervical stenosis: 200 µg vaginal at 10 and 4 hours prior, or 400 µg vaginal 4 hours prior 2
The 400 µg dose decreases placement difficulty but increases postprocedure cramping, particularly in nulliparous patients 2, 4
Cost and Practical Advantages
Misoprostol costs $0.36-$1.20 per 100 µg tablet, compared to $65-$75 for dinoprostone gel or $165 for dinoprostone insert 2, 1
Stable at room temperature, eliminating refrigeration requirements unlike dinoprostone 2, 1
Multiple routes of administration (oral, vaginal, sublingual, buccal, rectal) provide flexibility 9, 10
Common Pitfalls to Avoid
Never use in women with scarred uterus - the 13% rupture risk is unacceptably high and potentially fatal 1, 6
Avoid 50 µg doses for routine labor induction due to excessive hyperstimulation (35.86% vs 10.75% with 25 µg) and postpartum hemorrhage risk (9.78% vs 2.15%) 5
Do not use calcium channel blockers concurrently, as they may worsen outcomes in certain conditions 2
In advanced liver failure, consider alternative induction methods as misoprostol requires hepatic metabolism for conversion to active form 1
Ensure proper monitoring intervals - inadequate surveillance increases risk of undetected fetal compromise 2