Which sign is a classic indication of deep vein thrombosis (DVT)?

Unilateral swelling of the leg is a classic indication of deep vein thrombosis (DVT) because it is often the most noticeable and characteristic symptom associated with this condition. DVT occurs when a blood clot forms in a deep vein, commonly in the legs. The presence of the clot can obstruct normal blood flow, leading to fluid accumulation in the affected leg, which causes swelling.

While the other signs, such as warmth of the limb, pain in the calf upon flexion (often assessed with the Homan's sign), and redness around the ankle, can also occur with DVT, they are not as directly indicative of this condition as unilateral swelling. These signs may vary in intensity among individuals and can also be present in other conditions, making unilateral swelling a more definitive indicator of DVT.