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Emergency unblinding of a clinical trial participant — MRCEM SBA MCQ

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HardProfessional practice and researchEmergency unblinding of a clinical trial participantMRCEM SBA

A 69-year-old man attends an emergency department in England with ongoing haematemesis. His blood pressure is 78/46 mmHg despite initial blood-component resuscitation. Further resuscitation and urgent endoscopy are being arranged. He completed treatment for a deep-vein thrombosis three months ago and is now in a double-blind trial of extended treatment with apixaban or placebo; he took the study tablet three hours ago and takes no other anticoagulant. Knowing his allocation would determine whether apixaban reversal should be considered. You are the treating doctor and a delegated trial investigator. The protocol provides an immediately accessible emergency unblinding code, but the sponsor’s medical monitor has not answered the telephone. What is the most appropriate action regarding trial allocation?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: E — Use the emergency code now, then document the reason and notify the sponsor promptly.

This is severe, ongoing gastrointestinal bleeding with shock. Resuscitation must continue and urgent endoscopy is being arranged; determining trial allocation must not interrupt either. Because he recently took a blinded tablet and the result would affect whether apixaban reversal is considered, this is a clinical reason to unblind now. NICE recommends andexanet alfa as an option for life-threatening or uncontrolled gastrointestinal bleeding associated with apixaban, subject to its guidance. ([nice.org.uk](https://www.nice.org.uk/guidance/cg141/chapter/Recommendations)) The MHRA states that, when allocation is needed for optimal emergency management, the treating physician must have direct access to the unblinding procedure. Sponsor involvement must not delay it; the investigator should subsequently document and explain the unblinding to the sponsor. Thus **E** is best. ([gov.uk](https://www.gov.uk/government/publications/common-issues-identified-during-clinical-trial-applications/common-issues-clinical)) **A** delays a decision that may affect treatment before endoscopy. **B** avoids delay but risks making a reversal decision on an unverified assumption when the code is available. **C** makes the chief investigator’s approval a prerequisite despite immediate clinical need. **D** similarly treats an unanswered sponsor telephone call as a barrier, contrary to MHRA guidance. Preserving trial blinding matters, but not at the expense of timely care in this emergency. ([gov.uk](https://www.gov.uk/government/publications/common-issues-identified-during-clinical-trial-applications/common-issues-clinical))

Reference: MHRA: Common issues: Clinical — Unblinding in case of clinical emergency (28 April 2026) — https://www.gov.uk/government/publications/common-issues-identified-during-clinical-trial-applications/common-issues-clinical NICE CG141: Acute upper gastrointestinal bleeding in over 16s: management — Recommendations (2012; direct-acting oral anticoagulant reversal link updated March 2025) — https://www.nice.org.uk/guidance/cg141/chapter/Recommendations NICE TA697: Andexanet alfa for reversing anticoagulation from apixaban or rivaroxaban (2021; updated 2025–2026) — https://www.nice.org.uk/guidance/ta697/resources/andexanet-alfa-for-reversing-anticoagulation-from-apixaban-or-rivaroxaban-pdf-82609445558725