A 74-year-old woman with atrial fibrillation has 6 hours of severe, constant central abdominal pain. The abdomen is soft with minimal tenderness despite the pain intensity. Serum lactate is normal. Bowel sounds are present. What is the most appropriate next investigation?
- A Erect chest radiograph
- B CT angiography of the mesenteric vessels ✓
- C Diagnostic colonoscopy
- D Serum amylase
Correct answer: B. CT angiography of the mesenteric vessels
Explanation
Pain out of proportion to physical signs with atrial fibrillation is classic for acute mesenteric ischaemia from superior mesenteric artery embolism. A normal lactate does not exclude it because lactate rises only after transmural infarction, and waiting for biochemical change costs bowel. Contrast CT angiography is the investigation of choice, showing the embolic cut-off and assessing bowel viability. Colonoscopy risks perforation in ischaemic bowel and a normal chest film excludes nothing here.
Reference: Bailey and Love's Short Practice of Surgery, 27th ed.
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