Name the first-line uterotonic used to prevent/treat postpartum bleeding and one major adverse effect to monitor.

• A. Methylergonovine; marked hypertension.
• B. Carboprost; diarrhea.
• C. Oxytocin; hypotension with IV infusion and potential water intoxication with high-dose therapy.
• D. Misoprostol; fever.

Answer: (C)

Oxytocin is used first-line after delivery to promote uterine contractions and compress the blood vessels that can bleed postpartum, making it the go-to drug for preventing and treating postpartum hemorrhage. It’s typically given as a controlled IV infusion or an IM shot so that the contraction effect can be carefully regulated in the immediate postpartum period.

A major adverse effect to monitor is low blood pressure when given by IV infusion. If the rate is too rapid or the dose is high, oxytocin can cause hypotension, so vital signs and infusion rate should be watched closely and adjusted as needed. Another important consideration with oxytocin, especially with high-dose or prolonged therapy, is the risk of water intoxication due to its antidiuretic effect. This can lead to hyponatremia and central nervous system symptoms like confusion or seizures, so fluid intake and duration of high-dose therapy should be limited and monitored.

Other uterotonic options exist, but they carry different risk profiles and are not first-line. Methylergonovine can cause severe hypertension and is avoided in patients with hypertensive disorders; carboprost frequently causes diarrhea and bronchospasm; misoprostol can cause fever and GI symptoms.