Perioperative: massive transfusion: practice question

A General Surgery 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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General Surgery · Perioperative: massive transfusion

Sample item

A trauma patient receives 12 units of red cells over 2 hours. He develops hypotension, perioral tingling and a prolonged QT interval. Ionised calcium is low. What is the cause?

AAir embolism through the infusion lineBHypermagnesaemia from stored plasmaCPotassium load from stored red cellsDCitrate in stored blood chelating calcium

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

The answer and the reasoning

D. Citrate in stored blood chelating calcium

Stored blood contains citrate as an anticoagulant, which chelates ionised calcium. Rapid massive transfusion overwhelms hepatic citrate metabolism, causing hypocalcaemia with hypotension, tetany, paraesthesia and QT prolongation. Treatment is intravenous calcium chloride or gluconate. Hypothermia, hyperkalaemia and dilutional coagulopathy are other complications.

Option by option

A. Air embolism through the infusion line
Air embolism causes sudden hypoxia and collapse and does not lower calcium.
B. Hypermagnesaemia from stored plasma
Magnesium is not raised in this setting.
C. Potassium load from stored red cells
Hyperkalaemia gives peaked T waves and does not cause prolonged QT or low ionised calcium.
D. Citrate in stored blood chelating calcium (correct)
Citrate binding of calcium explains the low ionised calcium and prolonged QT.

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 General Surgery question

What is the answer to this General Surgery question?

The best answer is D, Citrate in stored blood chelating calcium. Stored blood contains citrate as an anticoagulant, which chelates ionised calcium.

Why is "Air embolism through the infusion line" not the answer?

Air embolism causes sudden hypoxia and collapse and does not lower calcium.

Why is "Hypermagnesaemia from stored plasma" not the answer?

Magnesium is not raised in this setting.

Why is "Potassium load from stored red cells" not the answer?

Hyperkalaemia gives peaked T waves and does not cause prolonged QT or low ionised calcium.

What concept does this question test?

It tests Perioperative: massive transfusion in General Surgery. Rapid massive transfusion overwhelms hepatic citrate metabolism, causing hypocalcaemia with hypotension, tetany, paraesthesia and QT prolongation. Treatment is intravenous calcium chloride or gluconate. Hypothermia, hyperkalaemia and dilutional coagulopathy are other complications.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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 Perioperative: massive transfusion?

Learn classic signs and eponyms alongside what they diagnose. Then use the flashcards and the other General Surgery 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.