27 Sept 2026 · Case #022
Acute mesenteric ischemia
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Diagnosis
Acute mesenteric ischemia
First-line treatment
Urgent revascularization (embolectomy) with resection of non-viable bowel
How the diagnosis is reached
Severe abdominal pain with a soft, benign-feeling abdomen, pain out of proportion to examination findings, is the signature of acute mesenteric ischemia, and it is the reason the diagnosis is so often missed. The visceral peritoneum is not yet involved, so guarding and rebound appear only once the bowel has infarcted transmurally, by which point the operative mortality is dismal. An akinetic apical segment after a recent anterior infarct is a mural thrombus waiting to embolise, and aspirin alone provides no protection; the superior mesenteric artery is a favoured destination because it leaves the aorta at a shallow angle. Raised lactate with a metabolic acidosis and a leukocytosis reflect ischemic tissue, and a modestly raised amylase is a recognised non-specific finding that can misdirect towards pancreatitis. CT angiography is the investigation of choice and must be arterial phase: a routine portal venous study can miss the occlusion entirely. The scan also says how much time is left. The jejunal walls are thin and poorly enhancing, ischaemic but not yet dead, and no free gas means nothing has perforated, which still permits revascularization first: open embolectomy or endovascular retrieval of the clot, then resection of only what is frankly necrotic, with a second-look laparotomy at 24 to 48 hours because marginal bowel declares itself late. Antibiotics, fluid resuscitation and systemic heparin run alongside. Survival turns on time to reperfusion, mortality passing 70% once transmural infarction is established, which is why the decision to operate rests on this scan rather than on waiting for the guarding that would confirm the diagnosis too late to act on it. The other lesson sits in her discharge summary: an akinetic apex after anterior infarction warrants anticoagulation, not aspirin alone.
Key clinical clues
- Pain out of proportion to a soft, non-peritonitic abdomen
- Recent anterior MI with an akinetic apex, an embolic source, on aspirin only
- Lactic acidosis with leukocytosis and a mildly raised amylase
- Severe pain persisting despite 15 mg of morphine
- Arterial-phase CT showing a filling defect in the superior mesenteric artery
The case in full
Presenting complaint
Patient history
A 74-year-old woman has four hours of severe, constant central abdominal pain that began abruptly. She has vomited twice and opened her bowels once. She had a large anterior myocardial infarction six weeks ago.
Examination and observations
Physical examination
She is distressed and cannot keep still. The abdomen is soft with only mild generalised tenderness, no guarding and no rebound. Bowel sounds are present.
| Parameter | Value | Reference |
|---|---|---|
| Heart rate | 108 bpmRef 60–100 | 60–100 |
| Blood pressure | 124/72 mmHg | – |
| Temperature | 37.2 °CRef 36.1–37.5 | 36.1–37.5 |
| Respiratory rate | 24 /minRef 12–20 | 12–20 |
Initial bloods
Laboratory results
Bloods and a venous gas are sent.
| Parameter | Value | Reference |
|---|---|---|
| White blood cells | 19.4 ×10⁹/LRef 4.5–11.0 | 4.5–11.0 |
| Lactate | 4.2 mmol/LRef 0.5–2.2 | 0.5–2.2 |
| pH | 7.28Ref 7.35–7.45 | 7.35–7.45 |
| Bicarbonate | 17 mmol/LRef 22–28 | 22–28 |
| Amylase | 142 U/LRef 30–110 | 30–110 |
Response to analgesia
Clinical course
She has received 15 mg of intravenous morphine in total. She still rates the pain 9 out of 10, yet the abdomen remains soft to palpation.
Cardiac assessment
Clinical course
The rhythm is sinus. Echocardiography performed after her infarct had reported an akinetic apical segment; she was discharged on aspirin alone.
CT angiography
Imaging
Arterial-phase CT of the abdomen is performed. A filling defect sits in the superior mesenteric artery a short distance beyond its origin, with the vessel beyond it opacifying poorly. Several jejunal loops are dilated with thin, poorly enhancing walls, and the adjacent mesenteric fat is hazy. There is no free intraperitoneal gas.