Does Intramyometrial Oxytocin Improve Outcome in Elective Cesarean Delivery?

Proposed doses were too large, bolus oxytocin may cause cases of arrythmias, and some even advocate slowing down the infusion rates that are currently used.

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: Determine if our standard 'low dose' oxytocin infusion is adequate prophylaxis to prevent need for additional uterotonics, including additional oxytocin; 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 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.

10 U intramyometrial oxytocin bolus immediately after cesarian delivery, and an infusion of 20 U/L of oxytocin at 500ml/hr.

10U intramyometrial normal saline bolus immediately after cesarian delivery, and an infusion of 20U/L of oxytocin at 500ml/hr.

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