Success Rate of External Cephalic Version at 36+4 Weeks in Third Pregnancy
As a multiparous woman at 36+4 weeks with a frank breech presentation that is not engaged, your probability of successful ECV is approximately 60-75%, with multiparity being the single strongest predictor of success.
Your Specific Success Probability
Your clinical profile includes several favorable factors that significantly increase your chances:
Favorable Predictors Present in Your Case
Multiparity (third pregnancy): This is the most powerful predictor of ECV success. Women with at least one prior vaginal delivery have significantly higher success rates compared to nulliparous women 1, 2, 3.
Frank breech presentation: While the evidence doesn't specifically differentiate frank from complete breech in success rates, frank breech is generally more amenable to version 1.
Not engaged: An unengaged presenting part is favorable, as descent of the presenting part into the pelvis is associated with lower success rates 3.
Additional Factors That Will Influence Your Success
The following factors, which should be assessed at your ECV appointment, will further refine your probability:
Amniotic fluid volume: Increased amniotic fluid index (AFI) is a significant independent predictor of success. Normal to increased fluid provides more space for fetal rotation 1, 2, 3.
Estimated fetal weight: Higher estimated fetal weight is associated with increased success rates, contrary to what might be intuitive 1, 2.
Placental location: An anterior placenta is an unfavorable predictor and reduces success rates 1, 3.
Fetal head palpability: Ability to palpate the fetal head abdominally is associated with higher success 3.
Quantifying Your Probability
Based on the prediction models developed in recent studies:
Best case scenario (multiparity + normal/increased AFI + posterior placenta + higher fetal weight): Success probability exceeds 60-75% 1, 3.
Moderate scenario (multiparity + normal AFI + anterior placenta): Success probability approximately 40-50% 1.
Lower probability (multiparity + oligohydramnios + anterior placenta): Success probability may drop to 20-30% 1.
The prediction model by Kok et al. demonstrated fair discrimination (area under the curve 0.71) and could distinguish between women with poor chance of success (<20%) versus good chance (>60%) 1.
Interventions to Maximize Success
Tocolytic medications significantly improve your success rate and should be used:
Parenteral beta-stimulants increase successful version rates (RR 1.68) and reduce the likelihood of failed ECV (RR 0.70), meaning you're 30% less likely to have a failed attempt with tocolysis 4.
These medications also reduce cesarean section rates (RR 0.77) if version is successful 4.
Regional Analgesia Consideration
Regional analgesia (epidural or spinal) combined with tocolysis is more effective than tocolysis alone, reducing failed ECV rates (RR 0.61) 4.
However, this requires more resources and may not be routinely offered at all centers 4.
Important Caveats and What Happens After
If ECV Is Successful
77% of women with successful ECV achieve vaginal delivery 3.
Risk of spontaneous reversion: Approximately 12-17% of successful ECVs will spontaneously revert back to breech before labor 5.
If reversion occurs, a second ECV attempt has a 76% success rate, though it's associated with a higher cesarean rate (33%) compared to fetuses that remain cephalic after first ECV (2.8%) 5.
Safety Profile
ECV is very safe with few complications, mostly mild 3.
Fetal bradycardia can occur but is typically transient 4.
No delivery should occur within 48 hours after ECV in uncomplicated cases 2.
If ECV Fails
You will need to plan for either cesarean delivery (most common approach) or vaginal breech delivery if you have access to a provider with appropriate expertise and meet criteria for safe vaginal breech delivery 6.
Be aware that cesarean delivery for breech presentation carries specific risks including impacted fetal head (occurs in at least 5% of cases), which can lead to uterine incision extensions, hemorrhage, and bladder injuries 6.
Clinical Bottom Line
Your multiparity gives you a strong baseline advantage for ECV success (60-75% range), and this can be further optimized with tocolysis and potentially regional analgesia. The procedure should be performed with ultrasound guidance, and your specific amniotic fluid volume, placental location, and estimated fetal weight at the time of the procedure will allow for more precise probability estimation 1, 3.