What is the name of the triad describing factors contributing to venous thromboembolism?

• A. Virchow's triad
• B. Well's triad
• C. PERC triad
• D. Doppler triad

Answer: (A)

Virchow's triad describes the three factors that predispose to venous thromboembolism: venous stasis, hypercoagulability, and endothelial injury. Blood flow stasis happens with prolonged immobility, hospitalization, or surgery, allowing clotting factors to accumulate. A hypercoagulable state can be inherited or acquired (for example, cancer, pregnancy, estrogen therapy, or inflammatory conditions), tipping the balance toward clot formation. Endothelial injury from trauma, surgery, or vascular instrumentation exposes underlying tissue factors and promotes platelet activation and coagulation. Together, these factors explain why deep vein clots form and can travel to the lungs as a pulmonary embolism.

Other terms like Well's criteria and PERC describe clinical decision rules for assessing or ruling out PE or DVT, not the underlying pathophysiology. A Doppler triad isn’t a recognized concept in this context.