What are two primary risk factors for in-flight venous thromboembolism?

• A. Prolonged immobility and dehydration.
• B. Prolonged immobility and hypertension.
• C. Dehydration and infection.
• D. Age and smoking.

Answer: (A)

In-flight VTE risk is driven mainly by venous stasis from prolonged sitting and by dehydration increasing blood viscosity. When you sit for long periods, the leg veins don’t have good return flow, which slows blood and promotes clot formation. Dehydration, common on flights due to low cabin humidity, reduces plasma volume and makes the blood more concentrated and prone to clotting. Together, these two factors directly create the conditions that raise the risk of a venous thromboembolism during air travel. While hypertension, infection, age, or smoking can influence clot risk in general, they aren’t the two primary in-flight factors as clearly demonstrated by this context.