Does Intramyometrial Oxytocin Improve Outcome in Elective Cesarean Delivery?

Does Intramyometrial Oxytocin Improve Outcome in Elective Cesarean Delivery?

Oxytocin use has become routine practice in elective cesarean delivery to promote uterine contraction and reduce blood loss. However, there is a lack of consensus regarding the best dose of oxytocin and the most effective route of administration. Most dosage and delivery systems have been empirically derived.

It is currently our practice at the Royal University Hospital to start an oxytocin infusion (20U/L) once the baby has been delivered. Some anesthesiologists use bolus intravenous oxytocin and it is occasionally requested by the obstetrician. A few obstetricians also choose to inject bolus oxytocin directly into the uterus (intramyometrial).

The primary objectives of the study include:

1. Determine if our standard 'low dose' oxytocin infusion is adequate prophylaxis to prevent need for additional uterotonics, including additional oxytocin;
2. Determine if the addition of prophylactic intramyometrial oxytocin improves both the primary outcome (uterine tone) and secondary outcomes (estimated blood loss, preoperative to postoperative change in hematocrit, need for additional uterotonics, and need for blood pressure support); and
3. Act as a dose finding study to determine if the intramyometrial dose is sufficient to augment uterine contraction.

The working hypothesis is that the use of intramyometrial oxytocin will not improve primary or secondary outcomes compared to the current practice of an oxytocin infusion alone.

Inclusion Criteria:

• Healthy Parturients
• Elective cesarean Delivery
• Term (> 37 wks gestational age) as defined by ultrasound or last menstrual period
• Singleton fetus
• Vertex presentation
• Age > 18
• BMI < 40
• Height > 5'2" and < 5"8"
• Written informed consent

Exclusion Criteria:

• Placenta previa
• Multiple gestation
• Preeclampsia
• Gestational Diabetes or pre-existing diabetes
• Macrosomia (estimated fetal weight prior to delivery)
• Polyhydramnios
• Oligohydramnios
• Uterine fibroids
• More than 2 previous cesarean deliveries
• Suspected adherent placenta (acreta/increta/percreta)
• Planned general anesthesia