Emergency medicine & Acute presentations — MRCEM SBA MCQ

Correct answer: A — Cardiac tamponade

The findings are classic for cardiac tamponade: hypotension, distended neck veins and muffled heart sounds form Beck triad, and pulsus paradoxus further supports tamponade physiology. In trauma, blood in the pericardial sac restricts diastolic cardiac filling, causing obstructive shock with raised venous pressure and reduced cardiac output. Tension pneumothorax can also cause hypotension and neck vein distension, but would typically have unilateral reduced breath sounds, hyperresonance and possible tracheal deviation rather than muffled heart sounds with Beck triad. Hypovolaemic shock usually causes flat neck veins, and simple pneumothorax does not cause shock.

Reference: Merck Manual Professional Edition. Cardiac Tamponade. Reviewed/Revised May 2026. https://www.merckmanuals.com/professional/injuries-poisoning/thoracic-trauma/cardiac-tamponade