Postpartum Haemorrhage from Uterine Atony
A 31-year-old woman with preeclampsia delivered vaginally 20 minutes ago and has ongoing bleeding of about 900 mL. The uterus is soft and boggy above the umbilicus. No lacerations or retained placental tissue are found, and blood pressure is 162/106 mm Hg. Which of the following is the most appropriate medical therapy?
- A.Intravenous oxytocin infusion, 20 units in 500 mLCorrect
- B.Intravenous ergometrine, 0.2 mg by slow injection
- C.Intramuscular ergometrine, 0.5 mg single dose
- D.Oral oxytocin, 5 units every 4 hours
Explanation
A soft, boggy, poorly contracted uterus with no lacerations and no retained tissue identifies uterine atony, which causes about 70 to 80 percent of primary postpartum haemorrhage. First-line medical therapy is an oxytocin infusion, typically 20 to 40 units in 500 to 1000 mL of crystalloid given intravenously, alongside uterine massage, bimanual compression, large-bore intravenous access, crossmatched blood and tranexamic acid within 3 hours. Oxytocin binds myometrial receptors to produce strong rhythmic contractions that mechanically compress the spiral arterioles in the placental bed. Ergometrine is a powerful second-line uterotonic but is a vasoconstrictor and is contraindicated in hypertension and preeclampsia because it can precipitate severe hypertension, stroke and pulmonary oedema; the intravenous route is particularly hazardous and is generally avoided in favour of intramuscular administration. Oxytocin is a peptide that is degraded in the gastrointestinal tract, so oral administration is ineffective. When oxytocin fails, options are carboprost (avoided in asthma), misoprostol, intrauterine balloon tamponade, uterine compression sutures, uterine artery embolization and finally hysterectomy. Prevention through active management of the third stage with prophylactic oxytocin remains the most effective measure.
Why each option
- A.
- Correct. Intravenous oxytocin infusion is the first-line uterotonic for atony and is safe in preeclampsia.
- B.
- Ergometrine given intravenously causes intense vasoconstriction and can precipitate a hypertensive crisis or stroke in a preeclamptic woman.
- C.
- Ergometrine by any route is contraindicated in hypertension and preeclampsia, and 0.5 mg intramuscularly exceeds usual dosing.
- D.
- Oxytocin is a peptide destroyed in the gastrointestinal tract, so oral administration has no therapeutic effect.
Reference: ACOG Practice Bulletin 183, Postpartum Hemorrhage (reaffirmed 2023); WHO Recommendations on Prevention and Treatment of Postpartum Haemorrhage, 2023
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