Prostaglandin Vaginal Suppository Administration
Oral Misoprostol is Preferred Over Vaginal Prostaglandins for Labor Induction
For labor induction with an unfavorable cervix, use oral misoprostol solution 20-25 µg every 2-6 hours rather than vaginal prostaglandin suppositories, as this results in fewer cesarean sections and lower rates of uterine hyperstimulation. 1
Dosing Protocol for Oral Misoprostol
- Start with 20-25 µg oral misoprostol solution every 2-6 hours as the evidence-based first-line regimen 1
- Lower dosages of 25 µg every 3-6 hours are effective for cervical ripening and labor induction 1, 2
- The 50 µg dose every 6 hours may be appropriate in select situations but carries increased risk of uterine hyperstimulation 1
- Maximum duration and number of doses should be determined by clinical response, with medication withheld once active labor begins or membranes rupture 3
If Vaginal Prostaglandins Are Used
When vaginal administration is chosen (recognizing oral is preferred):
- Misoprostol vaginal: 25 µg every 3-4 hours (lower dose than older studies to reduce hyperstimulation) 3
- Dinoprostone vaginal insert or gel: 0.5 mg intracervically every 6-12 hours for maximum of 3 doses 4, 5
- Place misoprostol tablets in the posterior vaginal fornix 4, 3
- Place dinoprostone gel into the endocervix 4
Absolute Contraindications
Never use misoprostol in women with previous cesarean delivery or uterine surgery in the third trimester - the uterine rupture risk is 13%, compared to 1.1% with oxytocin and 2% with dinoprostone 1, 2, 6, 7
Additional contraindications include: 7
- Cephalopelvic disproportion
- Grand multiparity (also increases rupture risk)
- Hypertonic or hyperactive uterine patterns
- Fetal distress where delivery is not imminent
- When surgical intervention is more appropriate
Required Monitoring
- Continuous fetal heart rate and uterine activity monitoring from 30 minutes to 2 hours after each dose 1, 2
- Monitoring must be performed by trained obstetrical personnel in a hospital setting 7
- Watch specifically for uterine tachysystole (≥6 contractions in 10 minutes for two consecutive 10-minute periods) 4
Clinical Advantages of Oral Misoprostol Over Vaginal Prostaglandins
- Fewer cesarean sections compared to vaginal dinoprostone (RR 0.84) 1
- Lower hyperstimulation rates compared to vaginal misoprostol (RR 0.69) 1, 2
- Significantly lower cost: $0.36-$1.20 per 100 µg tablet versus $65-$75 for dinoprostone gel or $165 for dinoprostone insert 1
- Stable at room temperature, eliminating refrigeration requirements 1
- Shorter time from induction to delivery compared to dinoprostone 4, 5, 3
Common Pitfalls to Avoid
- Do not use higher doses (50 µg) routinely - older studies used 50 µg vaginal misoprostol every 3-6 hours, but this caused excessive tachysystole (36.7% vs 11.9% with dinoprostone) and meconium passage (27.9% vs 10.5%) 4
- Do not continue dosing after active labor begins or membranes rupture 3
- Do not use in outpatient settings - FDA labeling specifies hospital use only for labor induction 7
- Oxytocin augmentation is needed more frequently with oral versus vaginal misoprostol (RR 1.29), so be prepared for this 1
Special Populations
- Advanced liver failure: Consider alternative induction methods, as misoprostol requires hepatic metabolism to convert from prostaglandin E1 to its active E2 form 1, 2
Postpartum Hemorrhage Management
When misoprostol is used off-label for postpartum hemorrhage treatment: 7
- Be aware of potential high fevers (>40°C/104°F) accompanied by tachycardia, disorientation, agitation, and convulsions
- These fevers are transient but require supportive therapy based on clinical presentation
- This indication requires hospital setting with appropriate monitoring 7
Failed Induction Management
If dinoprostone vaginal insert fails, a second induction cycle with either dinoprostone vaginal gel or oral misoprostol achieves active labor in approximately 70% and vaginal delivery in 62% of patients, with similar efficacy between agents 8