Recallab › Question bank › Obstetrics › #50386
Uterotonic choice in asthma
A primigravida with brittle asthma has atonic postpartum haemorrhage that has not responded to oxytocin and uterine massage. Which uterotonic must be avoided, and which is a safe alternative?
- A. Avoid methylergometrine; carboprost is safe
- correctB. Avoid carboprost; misoprostol is safe
- C. Avoid oxytocin infusion; carboprost is safe
- D. Avoid misoprostol; carboprost is safe
Explanation
Key fact
Carboprost is a prostaglandin F2-alpha analogue and a bronchoconstrictor. Misoprostol is prostaglandin E1 and does not constrict the airway.
Avoid carboprost; misoprostol is safe. The two prostaglandins act on different receptors with opposite airway effects.
Why
Prostaglandin F2-alpha constricts bronchial smooth muscle.
Carboprost is its analogue, and asthma is a recognised contraindication.
Misoprostol is a prostaglandin E1 analogue.
The E series relaxes rather than constricts the airway.
Misoprostol can be given rectally or sublingually when bleeding is heavy.
Uterotonics and their contraindications
Why not the others
- A. Avoid methylergometrine; carboprost is safe — identifies a real contraindication for the wrong reason. Ergometrine is avoided in hypertension and pre-eclampsia, not asthma - and carboprost is not safe here.
- C. Avoid oxytocin infusion; carboprost is safe — is wrong on both counts. Oxytocin is first line and safe in asthma.
- D. Avoid misoprostol; carboprost is safe — reverses the two. Carboprost is the one that provokes bronchospasm.
Remember
F for asthma is forbidden; E is fine.
Go deeper
If pharmacological measures fail, the sequence moves to tamponade with a balloon, then compression sutures, then devascularisation, then hysterectomy.
Tranexamic acid within three hours of onset reduces death from bleeding and should be given alongside uterotonics, not instead of them.
Latanoprost, which appears as a distractor in the source recall, is a prostaglandin analogue used topically in glaucoma and has no obstetric role.
DC Dutta's Textbook of Obstetrics, 11th ed. (Jaypee, 2026); Williams Obstetrics, 26th ed. (McGraw Hill, 2022).