What is the dosage and administration of intramuscular (IM) methergine (methylergonovine) for a postpartum patient with uterine atony?

Intramuscular Methylergonovine (Methergine) for Postpartum Uterine Atony

Administer methylergonovine 0.2 mg intramuscularly as a second-line uterotonic agent for postpartum uterine atony, but only after confirming the patient is not hypertensive. 1

Dosage and Administration

• The standard IM dose is 0.2 mg methylergonovine given as a single intramuscular injection 1, 2
• Methylergonovine is used after first-line oxytocin therapy (5-10 IU IV or IM) has failed to control bleeding from uterine atony 1, 3
• The medication works by increasing constriction of uterine musculature, facilitating sloughing of endometrial debris and closing uterine vessels 4

Critical Contraindications

• Methylergonovine is absolutely contraindicated in hypertensive patients due to >10% risk of severe vasoconstriction and dangerous blood pressure elevation 5, 1
• Avoid in women with asthma due to risk of bronchospasm 1
• Screen blood pressure before administration—this is a common pitfall that can lead to hypertensive crisis 5

Clinical Context and Positioning

• Methylergonovine remains the second-line uterotonic agent after oxytocin for both prophylaxis and treatment of postpartum hemorrhage 2, 3
• It is typically administered after uterine massage and oxytocin have been attempted without adequate response 6, 2
• The drug is highly effective as a second-line agent but carries more severe potential side effects compared to oxytocin 3

Expected Response

• When effective, methylergonovine produces a contracted uterus and cessation of bleeding within approximately 12.5 minutes on average 6
• The medication increases both amplitude and frequency of uterine contractions 6
• If bleeding persists after methylergonovine administration, proceed to third-line agents such as carboprost (prostaglandin F2α) or consider mechanical interventions like intrauterine balloon tamponade 1, 3

Common Pitfalls

• Never administer to hypertensive patients—this includes those with preeclampsia, chronic hypertension, or elevated blood pressure readings at time of hemorrhage 5, 1
• Do not delay moving to third-line therapies or mechanical interventions if methylergonovine fails to control bleeding 1
• Remember that methylergonovine is less commonly used as prophylaxis due to side effect profile; reserve primarily for treatment of established atony 2