## Oxytocin Dosing in Postpartum Hemorrhage **Key Point:** The standard bolus dose of oxytocin for PPH is 10 IU intravenously or intramuscularly. Higher bolus doses carry risk of maternal cardiovascular and neurological complications. ## Mechanism of Action Oxytocin binds to myometrial oxytocin receptors, triggering calcium influx and actin-myosin cross-linking, resulting in sustained uterine contraction and compression of spiral arteries in the placental bed. ## Dosing Regimen | Route | Bolus Dose | Infusion | |-------|-----------|----------| | IV | 10 IU | 10–40 IU in 500 mL saline over 15–30 min | | IM | 10 IU | Single dose | | Intrauterine | 2–10 IU | Direct injection into myometrium | ## Adverse Effects of High-Dose Oxytocin **Warning:** Doses >20 IU as a rapid IV bolus are associated with: - **Cardiovascular:** Hypotension, hypertension, arrhythmias, myocardial ischemia - **Neurological:** Seizures, cerebral edema, coma - **Renal:** Water intoxication (SIADH-like effect), hyponatremia - **Uterine:** Tetanic contractions, uterine rupture (rare) ## Clinical Pearl **High-Yield:** The 10 IU bolus is the evidence-based standard because it achieves adequate myometrial contraction with minimal systemic toxicity. If hemorrhage persists after 10 IU oxytocin + uterine massage, escalate to second-line agents (ergot alkaloids, prostaglandins) rather than increasing oxytocin dose. ## Mnemonic **OXYTOCIN BOLUS = 10 IU** — Remember: **1-0** (one-zero) is the standard; avoid exceeding it as a rapid IV push. ## Why 10 IU Is Correct This dose balances efficacy (produces sustained uterine contraction) with safety (avoids cardiovascular collapse and water intoxication). FIGO and ACOG guidelines uniformly recommend 10 IU as the first-line bolus.
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