Acute Mesenteric Ischemia: The Daily PANCE Blueprint
A 74-year-old woman with atrial fibrillation who stopped her anticoagulant two weeks ago presents with four hours of severe, diffuse, constant abdominal pain of abrupt onset. She has vomited twice and had one loose stool. She is writhing on the gurney, but her abdomen is soft and only mildly tender, with no guarding and no rebound. Her pulse is 118 and irregularly irregular; blood pressure is 104/62. Laboratory studies show a white count of 21,000 and a lactate of 4.2 mmol/L with a metabolic acidosis. Her creatinine is normal. Which of the following is the most appropriate initial diagnostic test?
A. Upright and supine plain abdominal radiographs
B. CT angiography of the abdomen and pelvis
C. Colonoscopy
D. Right upper quadrant ultrasound
E. Diagnostic laparoscopy
Answer and topic summary
The answer is B. CT angiography of the abdomen and pelvis
CT angiography of the abdomen and pelvis is the initial test of choice for suspected acute mesenteric ischemia, and the American College of Radiology rates it "usually appropriate" as the first study. It is fast, it is available at 3 a.m., and it does two jobs at once: it shows the occluded superior mesenteric artery and it shows the bowel — wall thickening, lack of enhancement, pneumatosis, portal venous gas. The single most important thing about this diagnosis is that you have to think of it before the abdomen looks sick. This woman is writhing in agony over a soft, benign belly — pain out of proportion to the examination — because the bowel is ischemic but has not yet infarcted through to the peritoneum. Once you get guarding and rebound, the wall is dead and the mortality climbs past 50%. Her setup is textbook: atrial fibrillation off anticoagulation throwing an embolus to the SMA. A lactate of 4.2 with a metabolic acidosis and a white count of 21,000 supports the suspicion but never rules it out — lactate rises late, and a normal lactate has sent far too many of these patients home. Do not wait for it. Get the CTA, call surgery and interventional radiology early, start fluids and broad-spectrum antibiotics, and anticoagulate. Sorting the distractors: plain radiographs are normal early and only turn abnormal — thumbprinting, pneumatosis, free air — once damage is done, so a normal film falsely reassures; colonoscopy is the test for ischemic colitis, a different and far more indolent disease, and insufflating a potentially necrotic bowel risks perforation; right upper quadrant ultrasound answers a biliary question nobody is asking here and cannot see the SMA well through bowel gas; and diagnostic laparoscopy is a reasonable endpoint if the patient is already peritonitic and unstable, but taking a stable patient to the operating room without the vascular anatomy in hand throws away the chance at endovascular revascularization.
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