Postpartum haemorrhage and emergencies: atony after prolonged oxytocin: practice question

A OBG question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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OBG · Postpartum haemorrhage and emergencies: atony after prolonged oxytocin

Sample item

After 14 hours of oxytocin augmentation, a woman delivers vaginally and then has a soft, boggy uterus that responds poorly to a further oxytocin infusion. Which explanation and plan fit best?

AOxytocin water intoxication, so stop all intravenous fluidsBOxytocin receptor desensitisation, so add a different class of uterotonicCHypocalcaemia, so give intravenous calcium as the main treatmentDPlacenta accreta, so proceed straight to hysterectomy

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. Oxytocin receptor desensitisation, so add a different class of uterotonic

Prolonged exposure to oxytocin down-regulates myometrial oxytocin receptors, so more oxytocin adds little. A second-line agent that acts through other receptors, such as an ergot alkaloid or a prostaglandin, is then used, with massage and bimanual compression as needed.

Option by option

A. Oxytocin water intoxication, so stop all intravenous fluids
Water intoxication causes hyponatraemia and fits, not isolated poor uterine tone.
B. Oxytocin receptor desensitisation, so add a different class of uterotonic (correct)
Correct. Receptor desensitisation explains the poor response, so a different uterotonic is needed.
C. Hypocalcaemia, so give intravenous calcium as the main treatment
Calcium is not first-line treatment for atony and nothing in the stem suggests hypocalcaemia.
D. Placenta accreta, so proceed straight to hysterectomy
Accreta presents with a retained, adherent placenta, not a delivered placenta with a boggy uterus.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this OBG question

What is the answer to this OBG question?

The best answer is B, Oxytocin receptor desensitisation, so add a different class of uterotonic. Prolonged exposure to oxytocin down-regulates myometrial oxytocin receptors, so more oxytocin adds little.

Why is "Oxytocin water intoxication, so stop all intravenous fluids" not the answer?

Water intoxication causes hyponatraemia and fits, not isolated poor uterine tone.

Why is "Hypocalcaemia, so give intravenous calcium as the main treatment" not the answer?

Calcium is not first-line treatment for atony and nothing in the stem suggests hypocalcaemia.

Why is "Placenta accreta, so proceed straight to hysterectomy" not the answer?

Accreta presents with a retained, adherent placenta, not a delivered placenta with a boggy uterus.

What concept does this question test?

It tests Postpartum haemorrhage and emergencies: atony after prolonged oxytocin in OBG. A second-line agent that acts through other receptors, such as an ergot alkaloid or a prostaglandin, is then used, with massage and bimanual compression as needed.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Postpartum haemorrhage and emergencies: atony after prolonged oxytocin?

Learn management algorithms as steps: PPH, eclampsia, ectopic pregnancy. Then use the flashcards and the other OBG questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.