What is the most effective dose of oxytocin (Oxytocin) for the prevention of postpartum hemorrhage (PPH)?

From the Guidelines

The most effective dose for oxytocin to prevent postpartum hemorrhage is 5 to 10 IU, administered as a slow IV or intramuscular infusion at the time of shoulder release or immediate postpartum. This recommendation is based on the 2022 guidelines for the management of urgent obstetric situations in emergency medicine, published in the journal Anaesthesia 1. The guidelines suggest that this dose can help reduce the incidence of postpartum hemorrhage.

Key Considerations

• The dose of 5 to 10 IU of oxytocin should be administered at the time of shoulder release or immediate postpartum.
• The oxytocin can be given as a slow IV or intramuscular infusion.
• This dose is recommended for prevention of postpartum hemorrhage in settings outside of a specialized maternity ward.

Administration and Mechanism

• Oxytocin works by stimulating the smooth muscle of the uterus to contract, which compresses blood vessels and reduces bleeding from the placenta site.
• The medication has a short half-life, which may necessitate continuous infusion in high-risk cases.
• Side effects can include hypotension, tachycardia, nausea, and vomiting, particularly with rapid IV administration, so slow administration is advised, as suggested by the guidelines 1.

Clinical Decision Making

• In clinical practice, the decision to use oxytocin for prevention of postpartum hemorrhage should be based on the most recent and highest quality evidence, which in this case is the 2022 guidelines 1.
• The guidelines provide a clear recommendation for the dose and administration of oxytocin, which should be followed to minimize the risk of postpartum hemorrhage.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION ... Control of Postpartum Uterine Bleeding Intravenous Infusion (Drip Method) – To control postpartum bleeding, 10 to 40 units of oxytocin may be added to 1,000 mL of a nonhydrating diluent and run at a rate necessary to control uterine atony

Intramuscular Administration – 1 mL (10 units) of oxytocin can be given after delivery of the placenta.

The most effective dose for oxytocin for prevention of postpartum hemorrhage is not explicitly stated in the label, but for control of postpartum uterine bleeding, the dose is 10 to 40 units of oxytocin added to 1,000 mL of a nonhydrating diluent, or 1 mL (10 units) intramuscularly after delivery of the placenta 2.

• The dose may vary depending on the individual patient's response and the rate necessary to control uterine atony.
• Monitoring of the patient is necessary to determine the effective dose.
• The label does not provide a specific dose for prevention of postpartum hemorrhage, only for control of postpartum uterine bleeding.

From the Research

Effective Dose of Oxytocin for Prevention of Postpartum Hemorrhage

• The most effective dose of oxytocin for preventing postpartum hemorrhage is not established, with studies suggesting a range of doses from 5 to 100 IU 3.
• Higher infusion doses (up to 80 IU/500 mL) and bolus doses of oxytocin appear to be more effective than lower doses or protracted administration of a fixed dose at reducing outcome measures of postpartum hemorrhage, particularly among cesarean deliveries 3.
• A study found that 10 units of intravenous oxytocin over 2-4 hours is as effective as 30 units over 8-12 hours in preventing postpartum hemorrhage after cesarean section 4.

Comparison with Other Uterotonic Agents

• Ergometrine plus oxytocin and misoprostol plus oxytocin may be more effective than oxytocin alone in preventing postpartum hemorrhage 5.
• Carbetocin, a long-acting analog of oxytocin, is likely the most effective single pharmacologic therapy for prevention of postpartum hemorrhage and need for additional uterotonics 6.
• A network meta-analysis found that ergometrine plus oxytocin and misoprostol plus oxytocin are the highest-ranked agents for preventing postpartum hemorrhage, with carbetocin and injectable prostaglandins having similar effects compared to oxytocin 5.

Timing and Administration of Oxytocin

• Intravenous injection of 5 IU oxytocin immediately after delivery of the fetal anterior shoulder is the treatment of choice for prevention of postpartum hemorrhage in patients with a natural course of labor 7.
• Administration of oxytocin at the end of the second stage of labor compared to after the third stage may reduce the risk of postpartum hemorrhage 7.