A parturient at 38 weeks gestation undergoes emergency Caesarean section under spinal anaesthesia. Post-delivery, she develops uterine atony with 1.5 L haemorrhage. Oxytocin is administered but fails to achieve uterine tone. The NEXT step in pharmacological management is:

• A Repeat oxytocin 5 units IV bolus
• B Ergometrine 0.5 mg IM (or IV slowly) to produce sustained myometrial contraction
• C Carboprost (15-methyl PGF2-alpha) 250 mcg IM as second-line uterotonic ✓
• D Misoprostol 800 mcg sublingual as the preferred second-line agent

Explanation

Management of oxytocin-resistant uterine atony follows a stepwise protocol. After maximum oxytocin, ergometrine is first-line second-step agent in many protocols (contraindicated in hypertension and pre-eclampsia). Carboprost (15-methyl PGF2-alpha) is the next step — a potent prostaglandin F2-alpha analogue causing intense uterine contraction; it is given 250 mcg IM every 15 minutes up to a maximum of 8 doses. Carboprost is contraindicated in asthma (can cause severe bronchospasm). Misoprostol (PGE1 analogue) may be used but is less potent than carboprost. The correct stepwise order per most PPH guidelines is: oxytocin → ergometrine → carboprost → misoprostol or tranexamic acid concurrently.

Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.