One-sided swelling needs careful assessment
Sudden swelling in one leg, especially with calf pain, warmth, redness, recent travel, surgery, pregnancy, cancer, or previous clots, can require prompt DVT ultrasound.
Chronic swelling may have venous causes
Longstanding ankle swelling, heaviness, varicose veins, skin darkening, or eczema can be related to venous reflux. Duplex ultrasound helps map the pattern.