30th April 2024

A 55-year-old woman with a history of obesity and recent knee surgery presents with swelling, pain, and redness in her left calf.

A 55-year-old woman with a history of obesity and recent knee surgery presents with swelling, pain, and redness in her left calf. She mentions that the symptoms have been worsening over the past two days. She denies any chest pain, shortness of breath, or recent travel. On examination, her left calf is swollen, warmer than the right calf, and tender to palpation. Homan’s sign is positive.

Which is the most appropriate diagnostic investigation?