What clinical finding differentiates phlegmasia cerulea dolens from other conditions?

Phlegmasia cerulea dolens is characterized by severe venous obstruction resulting from a thrombosis that affects both deep and superficial veins. This unique involvement differentiates it from other conditions, such as isolated deep vein thrombosis (DVT), where only deep veins are affected. The simultaneous involvement of both venous systems leads to significant clinical manifestations, including intense swelling, cyanosis, and pain, which are hallmark signs of this condition.

The presence of simultaneous thrombosis in both systems is crucial in identifying phlegmasia cerulea dolens, as it indicates a severe form of venous compromise that can lead to complications like venous gangrene if not promptly treated. Other conditions may present with unilateral involvement or varying degrees of venous reflux, but the combination of both deep and superficial vein thrombosis is specific to phlegmasia cerulea dolens. This differentiation is essential for the correct management and urgent intervention required for this condition.