Acute mesenteric ischaemia in an older patient on apixaban
A 78-year-old woman with atrial fibrillation on apixaban presents with 6 hours of severe periumbilical pain. She has vomited once. The abdomen is soft with mild periumbilical tenderness and no guarding. Blood pressure is 105/60 mmHg, heart rate 130/min and irregular, and lactate 3.8 mmol/L. White cell count is 18 × 10⁹/L and creatinine 150 µmol/L (eGFR 32). She is afebrile. She has no history of abdominal surgery. Contrast-enhanced CT is available, but the radiology registrar suggests a standard portal venous phase CT abdomen. The vascular surgery unit is 45 minutes away; there is no on-site vascular surgeon. She is on apixaban 5 mg twice daily, last dose 10 hours ago.
1. What is the most likely diagnosis, and what imaging would you request? Justify your choice.
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The most likely diagnosis is acute mesenteric ischaemia, likely due to a superior mesenteric artery embolus in the context of atrial fibrillation. The pain is out of proportion to the examination, and the lactate is raised. I would request a CT angiography of the abdomen and pelvis in the arterial phase, not a standard portal venous phase CT alone. The standard CT may show bowel wall thickening or pneumatosis, but it can miss a proximal arterial occlusion. The creatinine and eGFR should not delay CTA; the risk of contrast nephropathy is lower than the risk of missing a fatal diagnosis. The reasoning is that revascularisation is time-critical and the choice of open or endovascular approach depends on the anatomy.
2. The CTA shows a proximal superior mesenteric artery occlusion with bowel wall thickening but no free air. Outline your immediate management and the key decision about revascularisation.
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I would resuscitate with IV fluids, give analgesia, insert a nasogastric tube, and start broad-spectrum antibiotics. I would contact vascular surgery immediately and discuss heparin. If there is no peritonitis or free air, endovascular revascularisation may be preferred if the anatomy is suitable, followed by laparotomy if there is bowel necrosis. If there is peritonitis or perforation, I would go straight to laparotomy. The reasoning is that the bowel may be viable if revascularisation is achieved quickly; delay increases the risk of resection and death. I would not wait for a repeat lactate.
3. How would you manage her anticoagulation around transfer and possible surgery? Explain the competing risks.
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I would stop apixaban and start unfractionated heparin, unless there is active bleeding. Unfractionated heparin has a short half-life and can be stopped quickly if surgery is needed. I would check anti-Xa activity if available and discuss reversal with haematology; andexanet alfa or prothrombin complex concentrate may be used if there is life-threatening bleeding. The competing risks are extension of the mesenteric thrombosis if anticoagulation is withheld and bleeding if it is continued. The reasoning is that the patient needs revascularisation, and the surgeon needs to know the coagulation status. I would document the discussion and the plan.