"This is a 78-year-old independent woman with atrial fibrillation who stopped her apixaban four months ago. She has a five-hour history of a suddenly painful, cold right leg, with no pulses from the femoral downwards, a sensory and motor deficit, and no arterial Doppler signals in the foot."

"My working diagnosis is acute limb ischaemia, most likely from an embolus at the common femoral bifurcation. I favour an embolus over thrombosis because the onset was sudden, there's an obvious source in her untreated AF, she has no history of claudication, and the other leg is completely normal."

"Using the Rutherford classification, this is a category IIb limb, which means it's immediately threatened. She has sensory loss beyond the toes, weakness of toe dorsiflexion, and no arterial signal. Importantly, the venous signal is still present, which tells me the limb is still salvageable."

"In practical terms, she needs revascularisation within hours. If I found paralysis, fixed mottling, a rigid calf, or lost the venous signal, I'd reclassify her as category III, which would move the conversation towards primary amputation or palliation."

"I'd assess her with an ABCDE approach, get IV access and give her good analgesia, because this is extremely painful. Unless there's a contraindication, I'd give a bolus of unfractionated heparin followed by an infusion, to stop the clot propagating. I'd choose unfractionated heparin because it works immediately and can be reversed before theatre."

"I'd send a group and save, clotting, renal function and a CK, repeat her potassium, do an ECG and catheterise her. At the same time, I'd call my consultant and let theatre and the on-call anaesthetist know. And I'd talk to her early, explaining that her leg is at risk and that she needs an operation, and asking what matters to her."