A 79 year old woman, who had previously been fit and well, was referred by her general practitioner to the emergency medical unit with a three week history of a swollen right leg. She had previously been treated for possible cellulitis, with no improvement. She had no systemic symptoms and no risk factors for deep vein thrombosis. At initial presentation to the emergency medical unit she was documented as having a “unilateral swollen right leg, with no evidence of cellulitis.” The rest of the examination was normal. Baseline blood tests were normal, except for a positive D-dimer test. The impression was of a deep vein thrombosis, so she was treated with low molecular weight heparin and a Doppler ultrasound scan was booked as an outpatient. The results of the Doppler scan were normal and she was reassured and advised to see her general practitioner if the swelling worsened.

She re-presented to the emergency medical unit three months later with persistent swelling of the right leg, which she felt had slowly got worse. On examination, she had a grossly swollen right leg with pitting oedema up to the groin. She also had three large smooth mobile masses in the right inguinal region. Her pre-test probability score for deep vein thrombosis was 3. The results of a repeat Doppler …