Brief Answer:
investigation required

Detailed Answer:
Hello,

unilateral leg swelling warrants investigation for serious causes like deep vein thrombosis (DVT), particularly in patients with history of thrombosis, recent surgery, immobilization, etc. An ultrasound scan of the leg veins (triplex) is required to confirm or exclude DVT. Other causes may include local infection (fever, redness, swelling, warmth), lymphatic vessels' obstruction (for example tumor invasion of the inguinal lymph nodes), parasitosis, etc.

Since DVT is a serious and potentially life threatening disease, immediate investigation is required. An infectious process is also important although not as urgent in most cases as DVT, particularly when fever is absent.

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